Spaceborne lidars carry much promise for Earth observation and interplanetary missions to measure atmospheric parameters (wind velocity, optical extinction or species concentrations) and planet topologies. As the first European lidar mission, the European Space Agency is developing a Doppler wind lidar, ALADIN, to be launched on board ADM-Aeolus in 2008. ALADIN is a pulsed laser, emitting about 120 mJ of pulse energy in the UV. The mission duration is envisaged to be three years, which corresponds to several billion emitted pulses, thus imposing very stringent criteria on the longevity of the system. Laser-induced damage is one of the most significant issues here, in particular since laser-induced damage in space vacuum is still poorly understood. The European Space Agency has therefore established a test campaign to measure the power handling of all the instrument optics with laboratories in Germany, Italy, the Netherlands, the United Kingdom and France participating. Measurements are conducted at three wavelengths (1064nm, 532nm and 355nm) and with the introduction of several contaminants. The presentation covers laser-induced damage risk mitigation, the ESA test campaign and some test results.

SOI microwaveguides and associated devices (splitters, turns,...) are used for light distribution. Rib SOI geometries obtained by shallow etching of the silicon film offer definite advantages for the integration of active devices while fulfilling efficiency and compactness. Propagation losses of such waveguides are one order of magnitude smaller than for single mode strip waveguides. Rib-based compact and low loss optical signal distribution from one input to up to 1024 output points has been demonstrated. Light injection in submicron SOI waveguides is discussed. The indirect bandgap of silicon is not in favor of light emission and modulation. Realization of silicon sources and efficient high speed silicon-based modulators is a real challenge. For light detection, germanium can be grown on silicon and Ge photodetectors with -3dB bandwidths up to 30 GHz have been demonstrated.

We report on the fabrication and characterization of periodic nanoscale one- and two-dimensional surface structures in congruent 500 μm thick lithium niobate crystal samples. Structures with periods from 2 μm down to around 500 nm, lateral feature sizes down to 200 nm and depths compatible with conventional waveguide fabrication, have been obtained. Such structures are fabricated by applying polarity selective etching to periodically domain reversed samples obtained by electric field poling performed by overpoling regime. Holographic lithography is used to obtain sub-micron periodic insulating gratings to be used for selective ferroelectric domain reversal. The short pitch structures are attractive in a wide range of applications ranging from nonlinear optics, for short-wavelength conversion processes or backward second-harmonic generation, to the field of photonic crystals to fabricate novel tunable photonic crystal devices or electro-optically modulated Bragg gratings. Moreover moire beating effect is used in the photolithographic process to fabricate even more complex structures which could find applications in complicated photonic bandgap devices involving for example micro-ring resonators. In order to investigate the possibility to utilize these structures for photonic crystal applications, accurate topography characterization has been performed by using different techniques. Atomic force microscope provides high-resolution information about the lateral and depth feature size of the structures, while interferometric techniques, based on digital holography, have been used for wide field information about the homogeneity and periodicity of the structures.

A major challenge in science and engineering research and development at the nano-scale, and particularly for photonics, is the availability of infrastructure that allows easy and quick implementation of structures, devices, or more complex systems necessary for making rigorous measurements, other exploratory directions of interest, and building of assemblies that utilize techniques from multiple disciplines. The experiments connect across length scales - nanometers and up, employ a variety of materials and techniques of assembly and patterning, and require a complex mix of knowledge that are derived from other research areas and tools that are demanding in skills and are hard to access. The National Nanotechnology Infrastructure Network (NNIN; www.nnin.org) is funded by the National Science Foundation and is a partnership of open shared facilities across the country that enables the national community to pursue research and technology development that can benefit from nanotechnology. The NNIN provides easy hands-on access to external users, remote usage, staff support, low cost usage, knowledge infrastructure, and brings together an extensive coordinated array of instruments for fabrication, synthesis, and characterization together with other infrastructure resources. Particularly relevant to photonics is the ability to combine optical quality materials and fabrication techniques with ultra-sensitive characterization and application to biology, fluidics, and problems of interest in optical and electronic communication. Integration to the smallest length scales through synthesis and electron-beam lithography, growth and deposition of a variety materials with controlled properties, patterning of complex shapes in the three-dimensions, connecting such structures, characterization, and the ability to achieve this quickly and at low cost is essential to successful university research and industrial innovation. NNIN tool resources that span focused-ion beam, electron microscopy, spectroscopic techniques, etc. for characterization; synthesis, growth, deposition, etc. for assembling; utra-high resolution lithography, etching, etc. for patterning - all enable the researcher to focus on their own research interest by leveraging the NNIN infrastructure. Access of NNIN is designed for ease of use - quick access (typically, 2 weeks), strong support (direct staff and web-based interactions), and remote execution for simple projects.

Within the four main market segments of PV solar electricity there are already three areas competitive today. These are off-grid industrial and rural as well as consumer applications. The overall growth within the past 8 years was almost 40 % p.a. with a "normal" growth of about 18 % p.a. for the first three market segments whereas the grid connected market increased with an astonishing 63 % p.a. The different growth rates catapulted the contribution of grid connected systems in relation to the total market from about one quarter 6 years ago towards more than three quarters today. The reason for this development is basically due to industry-politically induced market support programs in the aforementioned countries. It is quite important to outline under which boundary conditions grid connected systems will be competitive without support programs like the feed in tariff system in Germany, Spain and some more to come in Europe as well as investment subsidies in Japan, US and some other countries. It will be shown that in a more and more liberalized utility market worldwide electricity produced by PV solar electricity systems will be able to compete with their generating cost against peak power prices from utilities. The point of time for this competitiveness is mainly determined by the following facts: 1. Price decrease for PV solar electricity systems leading to an equivalent decrease in the generated cost for PV produced kWh. 2. Development of a truly liberalized electricity market. 3. Degree of irradiation between times of peak power demand and delivery of PV electricity. The first topic is discussed using price experience curves. Some explanations will be given to correlate the qualitative number of 20 % price decrease for doubling cumulative worldwide sales derived from the historic price experience curve with a more quantitative analysis based on our EPIA-Roadmap (productivity increase and ongoing improvements for existing technologies as well as development of new concepts to broaden the product portfolio in coming years). The second topic outlines the most likely development of liberalized electricity markets in various regions worldwide. It will be emphasized that in such markets the future prices for electricity will more and more reflect the different cost for bulk and peak power production. This will not only happen for industrial electricity customers - as already today in many countries - but also for private households. The third topic summarizes the existing data and facts by correlating peak power demand and prices traded in various stock exchange markets with delivered PV kWh. It will be shown that a high degree of correlation is existent. Combining the three topics and postulating reverse net metering the competitiveness of PV solar electricity as described is most likely to occur. The described price decrease of modules will also have a very positive impact on off-grid rural applications, mainly in 3rd world countries. It will be shown that this is strongly advanced due to the development of mini-grids starting from solar home systems - with mini grids looking very similar to on-grid applications in weak grid areas of nowadays electricity network.

Polystyrene artificial opals are directly grown with embedded gold nanoparticles (NpAu) in their interstices. Reflectance spectra of samples having different sphere diameters and nanoparticles load clearly show a red shift of the photonic band gap as well as a reduction of its width without showing direct evidence of NpAu absorption. The case of transmission spectra is instead more complicated: here, overlapped to a broad NpAu absorption, a structure having unusual lineshape is detected. The infiltration of opal with NpAu removes the polarization dependence of the photonic band structure observed in bare opals. The lineshape of the absorption spectra suggest a spatial localization of the electromagnetic field in the volume where NpAu are confined thus enhancing its local intensity. This effect seems to be effective to stimulate optical nonlinearities of NpAu. Nanosecond transient absorption measurements on NpAu infiltrated opals indicate that a variation of transmission of about 10% is observed. Since this effect takes place within the pump pulse and since NpAu photoluminescence has been subtracted to the signal, we attribute it to an optical switching process.

Herein we present different results on the application of spin-coating to the processing of thin films made of spherical colloids ordered in three dimensional structures. We focus on the infiltration and controlled introduction of optical planar defects. We show that the use of spin-coating largely diminishes the processing time scales typically used in the field of colloidal crystals, and still allows one to attain high quality structures. We demonstrate that spin-coating permits the controlled infiltration of colloidal crystals with many different types of compounds. Examples are given for different oxide and polymer guest compounds introduced in the voids of the colloidal lattices. Both scanning electron microscopy and optical spectroscopy evidence of such control are provided. We also show that a thin layer of particulate material can be spread onto a colloidal crystal by spin coating a suspension of such particles in which control over the aggregation state has been achieved first. This gives rise to a capped lattice that present surface resonant modes and can be used to build a planar defect embedded in the bulk. In all cases, evidence of the optical quality of the different samples made is provided.

Spectra of the light scattered in the heterogeneous photonic crystal based on the thin triple-film opal, which was prepared by successive, convective force-assisted crystallisation of colloidal suspensions containing spheres of 374, 474 and again 374 nm in diameter, have been studied in the wavelength range of low order photonic bandgaps. If the ballistic regime of light propagation is preserved, the forward scattered light becomes the subject of the diffraction attenuation, whereas the backscattered light experiences both the diffraction enhancement and attenuation. A variety of possible configurations of scattered light measurements have been examined and corresponding spectra of scattered light have been compared with each other and with the spectra of transmitted and reflected light. The effect of the internal interfaces and the planar microcavity embedded in the photonic crystal upon the propagation of scattered light has been extracted.

Transmission spectra of thin opal films prepared by crystallisation in moving meniscus have been obtained in orthogonal polarisations in the wavelength range including the low and the high order photonic bandgaps. The anisotropy of light propagation in opal films has been studied as a function of the angle of light incidence, orientation of the opal lattice with respect to the light incidence plane, wavelength and polarisation of light. Clear correspondence between the spatial and the polarization anisotropy of light propagation has been demonstrated. The deviations of the opal film transmission from the commonly used model have been discussed.

We have fabricated three-dimensional (3D) colloidal crystals containing a defect by the Langmuir-Blodgett (LB) technique. A controlled number (from one to four) of layers of colloidal silica particles were inserted between two opal films of silica spheres of different size. The presence of the extrinsic defect led to an impurity mode within the photonic stop band, which was observed as a pass band in the near-infrared (NIR) spectra. The position of this defect mode was found to vary periodically with the value of the ratio of the thickness of the defect to the diameter of the colloids of the upper and lower opals. We also show that the amplitude of the pass band in the band gap is maximum when the two opals confining a defect monolayer made of smaller colloids have the same number of layers.

Photonic crystals exhibit exciting opportunities for controlling light. This can be utilized in optical waveguides, telecommunication devices, chemical and biological sensing and solar cells. However, functional devices require tuneable photonic crystals and ultimately structures that allow switching. Therefore inorganic-polymeric hybrid particles were developed, which offer new opportunities in the design of nanostructured materials since each component can be removed selectively. The presentation describes the synthesis of silica-polymer core-shell particles, absolutely uniform in size and in architecture. They were used as building blocks for colloidal crystals which served as templates for titania or tin disulfide inverse opals. Due to the inorganic-polymeric core-shell structure of the spheres, removing the polymeric shells by calcination yields the structure of Double Inverse Opal Photonic Crystals (DIOPC): The ordered, 3D array of air spheres in a high refractive index backbone is a host for movable silica spheres which behave as weakly scattering objects. The optical properties were determined by reflectivity measurements. Infiltration with liquids masks the silica-spheres optically, therefore introducing a transition of a diffusive scattering material to a selective reflection of specific wavelengths as known from ordinary inverse opals. This experiment simulates an order-disorder transition, induced by a collective shift of the random distributed silica-spheres into one specific position in the pores. The potential of switching a complete band-gap by a collective shift of the spheres to specific positions in the pores of the DIOPC is demonstrated by computational analysis.

We report the controllable and tunable fabrication of structurally modified non-close-packed inverse shell opals using multi-layer atomic layer deposition and present a model and simulation algorithm to calculate the structural parameters critical to fabrication. This powerful, flexible and unique technique enables opal inversion, structural modification and backfilling and was applied to the fabrication of TiO₂ non-close-packed inverse opals. Using successive conformal backfilling it was possible to tune the Bragg peak over 600 nm and enhance the Bragg peak width by >50%. Additionally, band structure calculations, using dielectric functions approximating the true network topology, were used to predict the optical properties during the fabrication process. 3D finite-difference-time-domain results predict experimentally achievable structures with a complete band gap as large as 7.2%. Additionally, the refractive index requirement was predicted to decrease from 3.3 in an 86% infiltrated inverse shell opal to 3.0 in an optimized non-close-packed inverse shell opal. It was also shown for these structures that the complete photonic band gap peak can be statically tuned by over 70% by increasing the backfilled thickness.

We present a bottom-up approach for the construction of tunable functional defects in colloidal photonic crystals (CPCs). These structures incorporate polyelectrolyte multilayer (PEM) planar defects embedded in silica CPCs through a combination of evaporation induced self-assembly and microcontact transfer printing. We show how the enormous chemical diversity inherent to PEMs can be harnessed to create chemically active defect structures responsive to solvent vapor pressures, light, temperature as well as redox cycling. A sharp transmission state within the photonic stopband, induced by the PEM defect, can be precisely, reproducibly and in some cases reversibly tuned by these external stimuli. These materials could find numerous applications as optically monitored chemical sensors, adjustable notch filters and CPC-based tunable laser sources.

We present a new method for calculation of optical and magneto-optical properties of three-dimensional magnetophotonic crystal heterostructures, composed from a sequence of homogeneous plates of a magneto-optical material and photonic crystal slabs. The algorithm is based on the layer KKR technique. As examples we consider the Bi:YIG (bismuth-substituted yttrium-iron-garnet) magneto-optical plate sandwiched by photonic crystal slabs consists of (i) simple cubic/face centered cubic lattices of SiO₂ spheres in the air; (ii) air spheres in silicon background (inverse opals). The enhanced Faraday rotation appears at the resonant transmission frequency in analogy with one-dimensional structures with magneto-optical microcavity. However, the calculated spectral behavior of the Faraday rotation as well as its dependence on defect thickness is quite different and unusual. For instance, the Faraday rotation angle changes its sign within the photonic band gap that is due to complicated reflection of waves from 3D photonic crystal slabs.

Photonic crystal device based on silicon nitride resonant cavity and acting as a band pass filter is presented. The devise consists of an incoming waveguide, coupling dipole cavity and outgoing waveguide. High transmission for resonant frequency and sufficient attenuation for other frequencies is achieved. Results of band gap and transmission calculations as well as the fabrication approach and fabricate structures are presented. Measurement setup to experimentally prove the predicted optical properties is presented.

Fabrication of three-dimensional photonic crystals by the microexplosion techniques has recently been demonstrated by a number of groups. However, simple models which are currently used for characterizing the void-based photonic structures do not produce adequate results. Here, we suggest a new theoretical approach for analyzing the properties of the three-dimensional photonic crystals which allow to improve the results of the theoretical modeling of the photonic crystals created by the microexplosion method. In particular, we study the bandgap spectrum of the three-dimensional photonic crystals introducing a shell of a high-index material surrounding an air void in the face-centered-cubic lattice. This allows us to suggest an effective theoretical model which correlates very well with the properties of the microexplosion polymer photonic crystals produced experimentally. We also discuss some interesting effects observed in the fabricated photonic crystals which until now have not been understood due to the inadequacies of simple models.

Laser-induced backside wet etching (LIBWE) allows the etching of transparent materials with pulsed UV-lasers. The laser-etched structures are characterized by a high fidelity and a low surface roughness. For the etching of periodically sub-micron structures on a solid surface interfering laser beams were used produced by projection of diffraction masks. In conjunction with LIBWE surface relief gratings were realized on planar and curved fused silica substrates in one-step direct fabrication process. The fundamentals of topography and roughness evolution of surfaces etched by LIBWE are investigated in detail. The etching of sub-μm gratings with a period of 760 nm into flat surfaces by means of interfering laser beams shows a saturation of the grating depth within 20 pulses. The decrease in height of sub-micron gratings from 125 to less than 10 nm within 15 laser pulses causes a substantial roughness reduction. The depth limitations in etching of the gratings are the result of the influence of the surface topography to the heat flow. The more efficient heating of surface peaks in contrast to the valleys results in higher etch rates and probably causes the smooth surfaces observed in LIBWE processing. The thermal diffusion length determines the structure dimension influenced by this "smoothing" effect. The knowledge on the effects of submicron resolved laser irradiation by LIBWE approach is from great importance for applying laser backside etching to nanometer grating fabrication. To demonstrate the capabilities of the processing approach a rectangular binary grating with a period was subsequently patterned with sub-micron relief gratings.

The two-dimensional periodic patterning of a high performance, rare-earth doped phosphate glass is presented here. A two step patterning method is adopted, wherein high damage is induced into the glass volume by exposure to intense ultraviolet pulsed, laser radiation and subsequently, a chemical development in a strong alkali, selectively etches the exposed areas. A four beam interferometric setup is used for defining the two-dimensional periodic pattern on the sample surface. The method presented here produces relief structures of high smoothness, free of debris or defects, and without extensive optical damage, compared to other approaches. The Bragg gratings imprinted here, are tuned for reflection operation in the 1.5μm band, having periodicities of the order of 500nm. The glass patterned is the phosphate glass IOG1, fabricated by Schott USA and codoped with Er and Yb. The exposures were performed by using the output of a high coherence 213nm, 150ps Nd:YAG laser; while the chemical developing was carried out in aqueous KOH solution. The inscribed periodic structures are characterized by means of diffraction efficiency, and surface topology by employing SEM and AFM scans. Issues related with the interferometric and wet etching processes are also presented and discussed.

We report the design and fabrication of small photonic crystal structures which are combined with conventional dielectric ridge waveguides. We describe in details the fabrication of both rough and smooth membranes, which are used as host for photonic crystals. Two Focused Ion Beam milling experiments are highlighted: the first one shows how photonic crystals can be fast and accurate milled into a Si membrane, whereas the second experiment demonstrates how focused ion beam milling can turn a rough surface into a well-patterned nano-smooth surface. The previously ultra rough surface showed no detectable roughness after milling due to the nanopolishing effect of the focused ion beam milling.

Miniaturization and integration are key drivers for future optical communication networks. Nanophotonic components are very interesting for ultra-dense photonic circuits, but the coupling with the outside world remains an important problem. An attractive solution is provided by grating couplers. In this paper, we present the design and fabrication of compact and efficient grating couplers in InP-membrane, for coupling between nanophotonic waveguides and single mode fiber. A high vertical index contrast is achieved by wafer bonding. First components show a coupling efficiency of 30%.

In recent years it became clear the relevance of photonic crystals when considering a nonlinear interaction. It has been shown in many occasions that the structuring of the material results in a clear enhancement of the nonlinear interaction. However, not too many structuring technologies can be applied successfully to materials that exhibit very good physical properties for the nonlinear generation of light. One of these is KTiOPO₄ (KTP), an inorganic material with high nonlinearity, large electrooptical coefficients, and very good transparency in the near infrared and visible range. In this paper, we propose a novel technique for growing two-dimensional KTP-air photonic crystals by liquid phase epitaxy employing a two-dimensional ordered macroporous Si matrix as a template.

We present experimental and theoretical investigations of tunable large-pore inverse opals fabricated by combining conformal films in patterned template structures with infiltrated liquid crystals. Ultra-conformal films allow opal templates to be inverted and used as scaffolding for fabricating a large-pore dielectric backbone that serves as a patterned template for electro-optic/non-linear or conventional materials. Additionally, theoretical results of tunable non-close-packed inverse opals fabricated by a multi-layer atomic layer deposition process and infiltrated with lead lanthanum zirconium titanate are presented. The structural properties of the device are defined by the template, while the dynamic properties are controlled independently by the choice of electro-optic/non-linear material. A variety of dielectric templates were modeled by choosing conformal coatings to define structures that exhibit either large Bragg peak tunability or width. The dynamic optical properties of the tuned large-pore and non-close-packed inverse opals are discussed and a model is presented for characterizing the controlled fabrication of optimized photonic crystal structures using multi-component conformal film deposition. Experimental measurements and modeling both indicate enhanced static and dynamic tunability to the photonic properties of infiltrated inverse templates compared to typical tunable opal-based inverse structures.

We report on electro-optical modulation with a sub-1-V sensitivity in a photonic crystal slab waveguide resonator which contains a nanostructured second-order nonlinear optical polymer. The electro-optical susceptibility in the core was induced by high electric-field poling. A square lattice of holes carrying a linear defect was transferred into the slab by electron-beam lithography and reactive ion etching, creating a photonic crystal slab-based resonator. Applying an external electric modulation voltage to electrodes leads to a linear electro-optical shift of the resonance spectrum and thus to a modulation of the transmission at a fixed wavelength based on the electronic displacement polarization in a noncentrosymmetric medium (Pockels effect). This effect is therefore inherently faster than other reported electro-optic modulation effects in nanophotonics.

We have investigated a three-dimensionally periodic (3D) photonic crystal structure based on an epitaxial periodic GaAs/Al_0.93Ga_0.07As multilayer structure that was designed for non-linear optical interactions. The 3D photonic crystal structure consisted of a two-dimensionally periodic planar photonic crystal hole pattern etched into the one-dimensionally periodic multilayer structure designed for a centre wavelength of λ = 1.6 μm. Numerical simulations on the 3D PhC structure have shown that it should exhibit slow group velocity modal features near the edge of the photonic bandgap.

This paper investigates the tunable characteristics of various photonic crystal structures infiltrated with nematic liquid crystals. A triangular lattice of air cylinders drilled into silicon provides the photonic crystal structure and the nematic material is inserted either in all or in properly selected air voids in order to create one-dimensional cavities or directional couplers. We have shown in previous studies that the spectral properties of such geometries can be tuned by means of applying appropriate static electric fields, which eventually determine the orientation of the liquid crystal molecules inside the cylindrical cavities. The essential aspect of the present study is to consider various profiles for the nematic director, which are associated with different molecular anchoring conditions at the confining surfaces, as well as electric fields of various strengths and orientation. In particular, we examine the cases of homeotropic or tangential surface anchoring orientation in the strong or weak anchoring limit, and more specifically focus on determining the impact of the transition from strong to weak anchoring, both on the operation of each structure and the associated range of tuning.

Polymer filling of the air holes of indiumphosphide based two-dimensional photonic crystals is reported. The filling is performed by infiltration with a liquid monomer and solidification of the infill in situ by thermal polymerization. Complete hole filling is obtained with infiltration under ambient pressure. This conclusion is based both on cross-sectional scanning electron microscope inspection of the filled samples as well as on optical transmission measurements.

If a number of experiments aiming at demonstrating fundamental properties of phononic crystals have been successfully implemented, a need for enlarging both the research and the application fields of these structures has more recently risen. Surface acoustic waves appear as appealing candidates to set a new ground for illustrative experiments involving some different physical concepts from those usually observed when dealing with bulk waves. The possibility of a direct excitation of these surface waves on a piezoelectric material, and their already extensive use in ultrasonics also make them an interesting basis for phononic crystal based, acoustic signal processing devices. In this work, wave propagation in a square lattice, piezoelectric phononic crystal consisting of air holes etched in a lithium niobate matrix is both theoretically and experimentally investigated. The crystal was fabricated by reactive ion etching of a bulk lithium niobate substrate. Standard interdigital transducers were used to characterize the phononic structure by direct electrical generation and detection of surface waves. A full band gap around 200 MHz was experimentally demonstrated, and close agreement is found with theoretical predictions.

We derive the Sommerfeld precursor and present the first calculations for the Brillouin precursor that result from the transmission of a pulse through a photonic crystal. The photonic crystal is modelled by a one-dimensional N-layer medium and the pulse is a generic electromagnetic plane wave packet which is incident perpendicular onto the crystal. Each layer of the crystal consists of two slabs that may differ in their relative thickness and in their refractive indices. The resulting precursors are then compared to those that would arise after propagation through a reference homogeneous medium of the same length and the same optical length in order to isolate the effect of the slab contrast onto the shapes of the precursors. The Sommerfeld precursor is not influenced by this slab contrast; its wavefront invariantly propagates at the speed of light in vacuum and its amplitude and period only depend on the spatial average of the two squared plasma frequencies of the slabs which coincides with the plasma frequency squared of the reference medium. The Brillouin precursor does experience the slab contrast; its arrival time increases with increasing slab contrast.

In this paper we present the application of a novel fully vectorial and three-dimensional computational method for planar devices to simulation of electromagnetic modes in classical and photonic-crystal-based VCSELs. We show the mathematical basis of the method and present results of computations of a resonant wavelength, optical losses, and a threshold gain of a classical arsenide VCSEL with oxide confinement and also of a purely photonic-crystal confined one. Furthermore we analyze the analytical reduction of computational domain to two dimensions in axisymmetric geometries with cylindrical-wave expansion, discuss the mathematical problems which occurs in such coordinates and suggest a method to overcome them.

We demonstrate the coherent control of the excited states of the atom embedded in a photonic band gap (PBG) structure by means of a Rabi oscillation. In this demonstration, we show that the atomic decay is strongly suppressed not only during the Rabi oscillation but also during switching process to the final steady state. This switching is achieved by eliminating one of localized field modes arising from the localization of the emitted photon in the vicinity of the atom due to the PBG, where the suppression of the atomic decay during the switching is facilitated by achieving this elimination not outside the PBG but inside the PBG. Such a coherent control of excited states without the atomic decay suggests the possibility of extending the atomic system for quantum computing to act as nearly lossless.

We report a new computational method based on the recursive Green's function technique for a calculation of light propagation in photonic crystal (PC) structures. The method computes the Green's function of the photonic structure recursively by adding slice by slice on the basis of the Dyson's equation, that relaxes memory requirements and accelerates the computational process. The method can easily account for the infinite extension of the structure both into the air and into the space occupied by the photonic crystal by making use of the so-called "surface Green's functions". This eliminates the spurious solutions (often present in the conventional finite-difference time domain methods). The developed method has been applied to study surface modes in semi-infinite photonic crystals and their application in surface-state cavities and waveguides. Namely, we demonstrate that confining PC surface states may result in enhanced intensity of an electromagnetic field on the surface and very high Q factor of the surface state. This effect can be employed as an operational principle for surface-mode lasers and sensors. We also show a possibility of using surface states as a novel type of waveguides and discuss their applications as efficient light couplers and directional beamers.

A method of inverse design is applied to generate a new family of optical devices. Three ultracompact devices are presented of only a few microns thick; a focusing device, a wavelength de-multiplexer and an optimized optical source. The designs consist of a few layers of 0.4μm × 0.4μm square-shaped bars etched in gallium arsenide. The proposed designs are examples of a scattering optical element, a name introduced to define a class of computer-generated optical devices whose functionalities are based on the multiple scattering by their individual constituents. For realization of the aforementioned devices, two-dimensional photonic plates could be fabricated by only a single integrated circuit processing procedure followed by micromanipulation assembling.

We call COUPLONICS the systematic extension of analytical Coupled-Wave Equations to two-dimensional Photonic Crystals, most specifically in the context of its application to coupled Photonic Crystal Waveguides. The present work is chiefly devoted to the generic study of a pair of mutually coupled periodic waveguides. Thoroughly investigating the cases where both co- and contra-directional coupling mechanisms are either distributed or localized, we prove the formally rigorous equivalence between the two configurations. By working in the basis of the eigenmodes, the general 2D problem of a periodic array of mutually coupled periodic waveguides can be reduced to a finite set of strictly 1D sub-problems. We use a normalization procedure that gives universal responses, in dimensionless parameters, whatever the dimensions - or even the physical nature - of the waves under consideration. These results illustrate once more the well-known deep behavioral analogies between electromagnetic, sonic or electronic waves in their respective "crystals".

A scattering theory for finite photonic crystals in terms of the natural modes of the scatterer is developed. This theory generalizes the classical Hilbert-Schmidt type of bilinear expansions of the propagator to a bilinear expansion into natural modes. It is shown that the Sturm-Liouville type of expansions for dispersive media differs considerably from those for non-dispersive media, they are e.g. overcomplete.

The formalism of the True Modal Method up to now written for diffraction gratings with a rectangular profile is extended to 1D-periodic structures with parallelogramic grooves. An appropriate coordinate transformation is proposed in order to express analytically in a simple form the modes propagating in the grating region. Numerical examples of calculation of the propagation constants of the eigenmodes of the grating and of the total diffraction efficiency of lamellar parallelogramic structures are given and results are compared with those obtained by other methods.

We present the concept of graded photonic crystals (GPC) and show its ability to enhance the control of light propagation. It is shown that gradual modifications of photonic crystal parameters are able to curve the path of light. This light bending which depends on the wavelength and on the incident angle is examined through parametric studies of the iso-frequency curves. We demonstrate that photonic mirages originate from the same physical principles as the usual atmospheric mirages. Two optical components based on two-dimensional GPCs presenting a super bending effect and a large beam shifting are presented.

We describe how two different kinds of ordered bimetallic nanostructures (Au/Pt, Au/Ag) with hierarchical porosity, such as macroporous nanostructures and nanostructures constructed from hollow spheres, can be selectively and conveniently fabricated by a general template technique on silicon wafers and on glass substrates, and how such nanostructures can find application in catalyst or surface-enhanced Raman scattering (SERS) substrates.

The use of a solid immersion lens (SIL) is a promising technique for increasing areal density in optical disks. This lens produces a high numerical aperture beam yielding to tighter focus. Both near-field and propagating waves are important for the formation of the high aperture focus at the SIL-air interface. The conventional SIL system generates evanescent waves carrying the high frequency information of the focus, necessary to maintain the small size of the spot. Thus the recording media is maintained in the high-amplitude evanescent wave vicinity. By attaching a new imaging component to the lower surface of a conventional solid immersion lens it is possible to refocus the first spot with its subwavelength dimension and analyse the mean corresponding properties: the propagation of electromagnetic waves in nanostructured material and restoration of the near-field waves in the image plane. This new nanostructured component can image the focus of the optical pick-up at the lower surface of the SIL to the active layer of the disk. We use numerical simulation through finite-element method to show how this new imaging structure can restore the near-field waves many wavelengths away from this component and conserve/enhance the size of the focus. So we take the example of a finite 2D periodic structure of dielectric with a subwavelength lattice constant. The parameters of the super-lens structure allow imaging of the immerged focus by amplification of the near-field waves.

Transmission properties of ultra-short pulses propagating through 1-D photonic crystals (PCs) with multiple cavities were experimentally investigated. Coupling between cavities is responsible for a wide resonance, inside the PC gap, suitable to distortion free propagation of 70 fs pulses at 800 nm. Geometry induced anomalous dispersion across the resonance allows chirp compensation of 70 fs pulses. We use an autocorrelator set-up in order to investigate chirp compensation effect by measuring the time duration of input and output pulses. Measurements are performed for different incidence angle. Results show that complete chirp compensation of 10 fs chirping occurs for an incidence angle of 20 deg.

1D and 2D compact photonic crystal reflectors on suspended InP membranes are theoretically and experimentally studied under normal incidence. They are based on the coupling of free space waves with slow Bloch modes of the crystal. We first present monomodal 1D photonic crystal reflectors. Then, we focus on multimodal 1D reflectors, which involve two slow Bloch modes of the crystal, and thus present broadband high-efficiency characteristics. 2D broadband reflectors were also investigated. They allow for an accurate control on the polarization dependence of the reflection. A compact (50 μm x 50 μm) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave (experimental stop-band superior to 200nm, theoretical stop-band of 350nm). These photonic crystal slabs can be used in new photonic devices as reflectors, where they can replace multilayer Bragg mirrors. The authors report a compact and highly selective tunable filter using a Fabry-Perot resonator combining a bottom micromachined 3-pair-InP/air-gap Bragg reflector with a top photonic crystal slab mirror. It is based on the coupling between radiated vertical cavity modes and waveguided modes of the photonic crystal. The full-width at half maximum (FWHM) of the resonance, as measured by microreflectivity experiments, is close to 1.5nm (around 1.55 μm). The presence of the photonic crystal slab mirror results in a very compact resonator, with a limited number of layers. The demonstrator was tuned over a 20nm range for a 4V tuning voltage, the FWHM being kept below 2.5nm.

Diatoms can be regarded as self-reproducing photonic crystal slab waveguides due to their silica cell walls that exhibit periodic pore patterns. The algae thus offer possibilities for biotechnological production of photonic crystals. Two techniques for incorporating organic laser dyes into the structures are demonstrated. First, Rhodamine B was covalently attached to the silica by an aminoalkylsilane linker. Second, highly fluorescent Rhodamine derivatives added to the culture medium were successfully taken up by the diatoms and deposited into the shell. By this techniques, it is possible to cultivate dye functionalized diatoms with emission behaviour adapted to photonic resonances.

We investigate the potential of photonic crystals (PCs) for use as novel sensing devices. For this purpose we study the interaction of nanoscopic dielectric particles with the near field of planar PCs by means of 3D FEM calculations. In particular, we have simulated PC waveguide structures incorporating a single cavity-like defect that interacts with a single dielectric nanosphere in a liquid environment. The resonance of the PC cavity shifts in the presence of the particle, as can be monitored by corresponding transmission measurements. As a second aspect, we investigate the mechanical forces acting on the particle due to the high field gradient in the cavity when in resonance. These forces give rise to a stable trapping of the particle in the cavity in analogy to the trapping in optical tweezers. In combination with microfluidic devices this gives prospect to novel techniques for ultra-sensitive detection and spectroscopy with only minimal amounts of analyte. We also present a scheme for experimental investigations of the particle-PC interaction, which makes use of an optical tweezer to actively move dielectric nanospheres in the near field of the PC, and which allows both for fluorescence as well as very sensitive force measurements.

We report on fabrication of high quality opaline photonic crystals from large silica spheres, self-assembled in hydrophilic trenches of silicon wafers by using a drawing apparatus with a combination of stirring. The achievements here reported comprise a spatial selectivity of opal crystallization without special treatment of the wafer surface, a filling of the trenches up to the top, leading to a spatially uniform film thickness, particularly an absence of cracks within the size of the trenches, and finally a good three-dimensional order of the opal lattice even in trenches with a complex confined geometry, verified using optical measurements. The opal lattice was found to match the pattern precisely in width as well as depth, providing an important step towards applications of opals in integrated optics. The influence of substrate structure on crystallization is also discussed.

We have developed a process for the direct fabrication of two-dimensional photonic crystals (PC) on large area surfaces that allows creation of defects and defect lines in the PC. The technique is based on lithography and laser beam interference in standard photoresist (PR). In a first step, multiple exposures of interference fringes define a two-dimensional lattice of pillars. Then the light of a Hg lamp is focalized with a microscope to create defect lines using a piezoelectric table. After development, the structures are transferred into silicon layer, deposed onto a glass wafer substrate by plasma etching. The result is a photonic structure of Si pillars where the light is confined in the plane by the PC and out of the plane by wave-guiding.

The possibility to create defined structures inside a synthetic opal is a key step towards applications in optics, where control of the propagation of light inside a photonic crystal is necessary. Here we report different methods for realizing defined embedded defects in opaline structures. Monodisperse colloids are synthesized by surfactant free emulsion polymerization of the acid labile monomer t-butyl-methacrylate (tBMA). The PtBMA colloids can be filled with sensitizer and photo acid generator and it is possible to crystallize them into photosensitive polymer opals. One method for the introduction of defects is a multilayer build-up of photo-labile (filled with photo acid generator) and photo-stable (not filled with photo acid generator) polymer beads. Irradiation through a mask with UV-light followed by baking and development with aqueous base allows subsequent patterning of the opaline film. Alternatively defects can be directly produced in the depth of an opal by two photon lithography. For this method a photo stable opal is infiltrated with ORMOCER, which is then polymerized. After removing the PtBMA opal an inverse opal structure is obtained. The holes are then filled with a resin and polymerization takes places at defined places via two photon lithography.

In recent years, photonic crystal fibres (PCF) have attracted much interest because of their unique possibilities in mode selection. They allow high index as well as low index core geometries and light guidance is provided either by modified total internal reflection or by the photonic bandgap. An example for the high index guiding type of PCF is the fibre with air-cladding, the subject of our investigation. We report on experiments to produce this type of fibre. The silica preforms consist of a central rod surrounded by tubes, all packed into a larger tube. Fibres have been drawn at various furnace temperatures, drawing forces, and pressures. A suitable set of parameters has been determined that allows drawing airclad fibres. The parameters are a furnace temperature of 1750°C, a drawing force of 0.25 N, and a pressure of 10 kPa. An air-clad fibre with only one hexagonal ring of holes produced with this set of parameters already shows guiding of light. Light propagation in this fibre is simulated with BeamPROP 6.0 computer code. The experimental results are compared to the simulations.

We report on the fabrication of photonic band gap fiber made of multicomponent glass. This fiber has a hexagonal lattice made of an array of 17 x 17 air capillaries with a lattice constant Λ=6.0 μm and air holes of diameter equal to d=5.7 μm. A hollow core is created by omitting seven central microcapillaries and have diameter of 16 μm. Characterization results show that the fiber can guide the light in the visible range with a central wavelength of 510 nm. The transmission properties for the presented PCFs are measured by using a broadband light source and an optical spectrum analyzer. In the paper we discuss also possible future modifications of the structures and their potential applications.

The paper reports numerical analysis of light propagation in a photonic crystal fiber filled with a nematic liquid crystal. Such fiber is not only an advanced anisotropic structure, but also can experience a change in its light propagation mechanism: from index guiding to the photonic band gap mechanism. Both of these mechanisms can be extensively tuned due to variations of liquid crystals and silica glass refractive indices differences. The obtained numerical simulations are confirmed by experimental results.

The paper analyzes polarization properties and presents the latest experimental results on polarization phenomena occurring in microstructrured photonic liquid crystal fibers (PLCFs) in which only selected micro holes or holes areas were filled with prototype nematic liquid crystal guest materials that are characterized by either extremely low (of the order ~ 0.05) or relatively high (of the order ~ 0.3) material birefringence. The photonic crystal fiber host structure was a commercially available highly birefringent PCF (Blazephotonics). The PLCFs under investigation have been powered by a tunable laser operating at infrared. Due to anisotropic properties of the microstructured PLCFs, switching between different guiding mechanisms as well as electrically and temperature-induced tuning of both light propagation and fiber birefringence has been demonstrated.

We present the details of the Sol-gel processing used to synthesize silica spheres, with particular attention to the conditions that permit to tailor their dimension. We have elaborated a protocol in order to obtain silica micro spheres with low polydispersivity and we have demonstrated that large well-ordered crystals of synthetic opal, that exhibit a photonic stopband, can be produced in few days by vertical deposition and evaporation-assisted sedimentation deposition methods. Scanning electron microscope was employed to characterize the samples reflectance and transmission measurements were used to put in evidence the high quality of the realized opals. Starting from the silica spheres, core-shell-like Er³⁺-activated silica spheres were also prepared, where the core is the silica sphere and the shell is an Er₂O₃-SiO₂ coating. Morphologic, structural and spectroscopic properties were investigated by scanning electron microscope and luminescence spectroscopy. The emission of ⁴I_13/2→⁴I_15/2 of Er³⁺ ion transition with a 27 nm bandwidth was observed upon excitation at 514.5 nm. The ⁴I_13/2 level decay curves presented a single-exponential profile, with a lifetime of 12.8 ms.

A numerical approach based on the two-dimensional (2D) Finite Difference Time Domain (FDTD) is employed to design, analyse and optimise the wavelength demultiplexer (WDM) based on photonic crystal waveguide couplers. The performance of the WDM is investigated in terms of device length, optical efficiency and losses. Significant improvement on the power efficiency and the wavelength directionality has been achieved by introducing a single defect on the crossing point between two photonic crystal waveguides.

We demonstrate the possibility of waveguiding electromagnetic waves in a monolayer of dielectric spheres. While light is confined vertically by index guiding, a triangular superlattice monolayer of spheres was found to exhibit a photonic band gap below the light cone, thereby preventing light from propagating laterally. A gap map of this structure is presented. We propose a possible waveguide configuration that yields two non-degenerate defect modes lying within the photonic band gap. Such a structure may be particularly interesting for coupling light into self-assembled colloidal photonic crystals.

The variation of magnetic permeability of substrate on Photonic Band Gap (PBG) has been studied for microstrip type periodic metallic structure and the experimental findings will be presented and discussed. Periodic structure was carved out in the metallic foil of 18 micron thickness and was put on the composite of magnetic and dielectric substrate. As the dielectric constant of the substrate affects the band gap for the photons in the microwave region, the combined effect of magneto-dielectric substrate have been studied here for different combination of ferrite materials with different composition and different sintering temperature. The substrate of Ni-Zn ferrite was prepared on the Perspex sheet of desired dimensions. The behavior of variation of band gap was also been studied for the air as dielectric material of the substrate. We found a well defined PBG and the band gap increases and transmission loss decreases in the microwave region with appropriate combination of magnetic and dielectric substrate. Thus it could be concluded that the dielectric constant viz. a viz. magnetic permeability plays an important role in the formation of broad band photonic materials for the microwave applications such as filters, antennas, frequency selective surfaces etc. Further work is going on to fabricate the patch antenna on the PBG embedded ground plane.

We investigate the optical properties of thin films of two photonic systems: synthetic opal and crystalline liquid BPII. Diffraction related with three-dimensional periodic structure and interference related with light reflection from film surfaces were measured. We found a substantial change of refractive indices at the edges of the photonic bands in both materials. The relation between the frequency and the wave vector of light shows a nonlinear behavior near zone boundary.

Investigations of the spontaneous and stimulated emission spectra by optical pumping of ZnO layers deposited on SiO₂-Si and opal were carried out. The stimulated emission pumped under ultra violet 337 nm N₂ laser excitation was observed at 397 nm at room temperature from ZnO-SiO₂-Si type and ZnO-opal type thin film structures. The threshold pumped power for the electron-hole plasma recombination laser process is of the order of 35 MW/cm² for ZnO-SiO₂-Si and 300 KW/cm² for ZnO-opal structures.

This letter deals with the possibilities of flexible control of dispersion governed by geometrical parameters such as core's size and normalized hole diameter d/Λ. Curves of total dispersion in function of wavelength, normalized hole diameter and core's size are presented. Limitations of possible run of total Group Velocity Dispersion like possibility of high order mode zero-dispersion wavelengths appearance is presented as well as possibility of deterioration of further important transmission parameters such as loss or modal regime is discussed. The set of structural set of the fiber is described.

We present the results of experimental and theoretical analysis of dispersion characteristics of a two-mode birefringent holey fiber, in which the birefringence is induced by two large holes adjacent to the fiber core. Different interferometric techniques were used to measure in a broad spectral range the wavelength dependences of the phase and the group modal birefringence for the fundamental and the higher-order linearly polarized (LP) spatial modes. We also measured the wavelength dependence of the intermodal dispersion for two orthogonal polarizations of the fundamental and the higher-order LP spatial modes employing a white-light spectral interferometric method. Furthermore, we calculated all the dispersion characteristics using a full-vector finite-element method and confirmed good agreement between experimental and theoretical results.

The most interesting phenomena in photonic crystals stipulate the presence of omnidirectional band gap, i.e. overlapping of stop bands in all directions. Higher rotational symmetry and isotropy of quasicrystals in comparison with ordinary crystal give a hope to achieve a gap opening at lower dielectric contrasts. But nonperiodic nature of quasicrystals makes the size of stop bands lower than in the case of ordinary periodic crystal. We study transition from periodic structure to nonperiodic one by considering pseudoquasicrystals - quasicrystal approximants with growing period to weigh advantages and disadvantages of quasicrystals. We consider the structures that can be obtained by multiple exposure holographic lithography for the case of 2, 3, 4, and 6-fold exposure by two wave interference pattern, corresponding square, hexagonal, 8-fold and 12-fold symmetry lattice.

One-dimensional (1D) photonic crystals composed of alternating stacks of layers having a low and a high index of refraction was recently shown to act as omnidirectional reflection band. They reflect light at any polarization, any incidence angle, and over a wide range of wavelengths. In contrast to the three-dimensional case the 1D photonic crystal is attractive since its production is more feasible at any wavelength scale. When a structural defect is introduced in the photonic crystal, photon-localized state can be created in the photonic band gap. In 1D photonic crystal, the defect can be used to open controlled optical windows in the photonic band gap or to obtaining an omnidicrectional photonic band gap. We can find more types of defects that play the role of broking the periodicity of the photonic crystal to produce new physical phenomena or new quasi-periodic systems. A design procedure for omnidirectional high reflectors with wide bandwidths for the optical telecommunication bands is described. From the numerical results performed by the transfer matrix method, it is found that a partially omnidirectional high-reflector covering the optical telecommunication wavelengths 1.3 and 1.55μm is obtained for a quarter-wave stack air/H(LH)¹²/air by using the tellurium as a materiel of high refractive index (n_H=4.6). The study of a deformed stack which be constructed according the quasiperiodic sequences (Fibonacci and Thue-Morse) so that the coordinates y of the deformed object were determined through the coordinates x of the Fibonacci stack in accordance with the following rule y = x^k+1 leads to an omnidirectional high reflector band covering the all optical telecommunication wavelengths, here k is the coefficient defining the deformation degree. The reflection properties of one-dimensional generalized Cantor-like multilayer (GCLM) are investigated numerically in the visible range. Strong correlation between the stack geometry and the properties of the optical reflection spectra is found, namely spectral scalability and sequential splitting. The construction of multilayer systems according to the definite Cantor distribution brings improvements to the reflection properties. In particular, the widening of the band gap and the thin peak appearance in the reflection spectra whose number increases with the division number in the (GCLM). Optical properties of (GCLM) inserted between two periodic stacks are numerically investigated. We chose SiO₂(L) and TiO₂ (H) as two elementary layers. The study configuration is H(LH)^j[GCLM]^PH(LH)^j which forms an effective interferential filter in the visible spectral range. We show that the number of resonator peaks is dependent on the repetition of the number P of the (GCLM). The best performances are obtained in particular for the symmetrical configurations of the (GCLM) and especially for P an odd number.

We analyse the coupling characteristics of dual-core photonic crystal fibre couplers by a 3D finite difference vector beam propagation method. Beam propagation analysis of photonic crystal fibre couplers is performed in terms of coupling length and coupling efficiency. The determination of the guiding properties such as the propagation constants is evaluated using a mode solver based on plane wave method. We study the influence of the photonic crystal fibre coupler geometrical parameters on the coupling length at different wavelengths. Variable size of the central hole is considered to improve the coupling between the two cores. It is shown that it is possible to design shorter photonic crystal fibre couplers with coupling lengths of hundred micrometers compared to conventional optical fibre couplers. We demonstrate that the designed coupler can operate as a polarization preserving directional coupler. This study confirms that this device can act as an efficient ultra small wavelength selective coupler.

We investigate the way of detecting changes in dielectric function of biological entities in liquid phase such as living cell, neurons and proteins. These studies will be used to extract some biological mechanisms information. On this purpose, we have designed a one dimensional EBG (Electromagnetic BandGap) structure with a defect at terahertz frequencies. It is now well known that such a structure presents a transmission peak in the forbidden band with a high quality factor. Here the defect is a microchannel placed below a transmission line. We will show this BioMEMS in two configurations: (a) with classical transmission lines (CPW or Microstrip) and (b) with original transmission lines. We have recently demonstrated a way to excite a propagating mode (also known as Goubau mode) on a very thin single metal wire transmission line. For this propagating mode, the electromagnetic field is very highly confined around the metallic strip. We will briefly detail the properties of such a line and its excitation. We will then show the variations of the defect mode in the forbidden gap with the variation of the dielectric permittivity of the solution. The designed BioMEMS is in a planar topology with glass and quartz substrates.

In dielectric structures such as photonic crystals that combine two types of materials it is likely that one may find a large degree of disorder. This is also true for nonlinear photonic crystals that combine two different orientations of the same material or a nonlinear with a linear material. Such a disorder may not always be detrimental for the propagation or generation of light. In the present work, we consider second harmonic generation in one-dimensional disordered nonlinear structures. When considering a random sequence of two different orientations of the same material, we show that second harmonic generation does not vanish but instead it exhibits a linear grow with respect to the number of domains considered. In structures that combine a nonlinear with a linear material, even when a large degree of disorder is introduced by allowing an extremely large dispersion in the size of the domains, the coherence of such second order nonlinear process is shown to survive.

Photonic bandgap effects in reflectance and photoluminescence of silica opal-based photonic crystal with embedded europium (III) salt of ethylenediaminetetraacetic acid (HEuEDTA) were studied. The position of the bandgap was accurately fitted to the wavelengths of visible lines of Eu³⁺ photoluminescence by proper choice of the size of SiO₂ spheres. High spatial anisotropy of photoluminescence was observed by spatially- and spectrally-resolved laser spectroscopic measurement. The influence of crystal structure quality on spatial anisotropy of photonic bandgap and photoluminescence is discussed.

We present experimental realization of nonlinear and highly birefringent microstructure fiber fabricated from silicate glass. Using full vector FEM mode solver the numerical analysis of reported fiber is performed and its modal, polarization and dispersive properties are investigated. Particularly, the calculations reveals guidance of two orthogonally polarized eigenmodes with the difference of its effective indexes B=0.0025 for wavelength λ=1.55 μm. Additionally, spectral broadening of the 50 fs Ti:Sapphire laser impulses with average power 150mW coupled into 39 cm section of the fiber is observed.

We report on experimental studies of polarimetric sensitivity to temperature and hydrostatic pressure in two highly birefringent index guided photonic crystal fibers. Our results confirm earlier theoretical predictions indicating that polarimetric sensitivity to temperature in highly birefringent PCF with specific constriction can be very low. Proper choice of constructional parameters of the PCF can lead to complete temperature desensitization. On the other hand, relatively high polarimetric sensitivity to hydrostatic pressure in the analyzed structures make them good candidates for applications as active elements in hydrostatic pressure sensors.

In the paper we report on development of all-solid holey fibers. Numerical analysis of dispersion properties of such fibers is also presented. The periodic microrods that forms cladding are made of glass instead of air. Use of two or more multicomponent glasses in the fiber structure allow to manipulate refractive index contrast in the structures which is not possible in holey fibers. The all-solid holey fibers offer additional degree of freedom to the designer for determination of dispersion in fibers than in case of air-holes PCFs. Moreover a fabrication of all-solid PCFs allows to better control of geometry and uniformity of the cladding structure design.

We demonstrate the use of broad super-continua generated in photonic crystal fibers (PCFs) for a novel femtosecond absorption pump-probe experiment that records time- and wavelength resolved data. While such experiments relied up to now on amplified sources for the supercontinuum generation, the non-linearities in the microstructured fibers can be induced with a Ti:sapphire oscillator only. We test the performances of such a compact femtosecond spectrometer for the study of molecules in the liquid phase. The aim is to cover the 400-1100 nm spectral range with a single pulse shorter than 200 fs. A commercial Ti:Sapphire oscillator (KM Labs) cavity, delivering 40 fs pulses, has been extended so as to lower the repetition rate (27 MHz) and to increase the pulse energy. Up to 6 nJ are focussed into 8-mm long pieces of commercial (NL-710, Blazephotonics) and home-made PCFs using a microscope objective. The fiber output spectra are measured from 300-1100 nm with a Peltier-cooled CCD (Spec10, Roper Scientific). Most recently, using the fibers produced at XLIM, we have been able to generate a supercontinuum spectrum extending down to 380 nm. While a full characterization of the temporal properties of the home-built fibers is still in progress, we find a single pulse output for the commercial fibers, with negligible chirp for λ= 600-750 nm. Obviously in these short fiber lengths, soliton fission does not take place. With this system the photo-induced dynamics of malachite green have been studied with a noise-floor of 10^-4 relative absorption change.