The lowest oscillating waveguide mode can exist in guiding layer of a double-negative material that is symmetrically encapsulated in a double-positive material, even when the guiding layer's thickness is many times smaller than the operating free-space wavelength.
In this paper, we apply the coordinate transformation technique to the design of perfect lenses, which are able
to perfectly reproduce an image on another surface. In particular, anisotropic metamaterials that magnify
two-dimensional planar images beyond the diffraction limit are designed by the use of spheroidal coordinates.
We show that the technique can be used to design transformation media that magnify images beyond the
diffraction limit.
A dual-order Raman fiber laser (RFL) is numerically presented with suppressed low-frequency relative-intensity-noise
transfer from pump sources to both the first- and second-order Stokes output. It is accomplished by generating the
amplified spontaneous emission near second-order Stokes shift from the launched pump. Their powers can be tuned in a
large dynamic range. Besides these, the low-power second-order Stokes output is also stabilized in the RFL setup. These
special behaviors fit the proposed RFL for use as dual-order pump sources in Raman fiber amplifiers.
In this paper, we investigate the possibility of superlensing with two dielectric planar waveguides in detail by studying
the transmission of evanescent waves through one double-waveguide structure. We derive the total transmission and
reflection coefficients for the double-waveguide structure. It is found that when one field component of an evanescent
wave coincides with one of the single-waveguide bound-state eigenvalues, the total transmission increases exponentially
with respect to the distance between two dielectric planar waveguides, and zero reflection can be found. An important
interplay between propagating waves and evanescent waves on image formation is revealed, which makes the
appearance of the image of a superlens substantially different from that of a real image behind a free space. We derive
the resolution of the double-waveguide structure and infer that resolution arbitrarily smaller than the wavelength should
be possible in principle, provided that sufficiently high dielectric contrast of two waveguides can be obtained. The
numerical results confirm the qualitative discussions in this paper.
A systematic study of the omnidirectional reflection range (ODR) of one-dimensional (1-D) staggered photonic crystals
(PC) containing negative refraction medium (i.e., negative index medium (NIM)) is presented, based on numerical
simulations performed with the well-known transfer-matrix method without any simplifying assumptions. It is found that
total omnidirectional reflected frequency band is enlarged considerably by using onedimensional photonic crystal
structure composed of alternate layers of positive index material (PIM) and NIM. We discover that the ODR in staggered
1-D PCs range can be significantly broadened in a staggered structural design.
In this paper, we focus on the properties of the complex modes in negative-refractive-index fibers. The characteristic
equations for TE and TM modes in negative-refractive-index fibers are given. These solutions, termed complex surface
waves, form another set of proper modes. We show that dispersion diagram for both TE and TM modes in
negative-refractive-index fibers, including evanescent, ordinary, and complex surface modes. It is found that the complex
surface modes have high cutoff frequencies which means they exist only when the frequency is lower than their
respective cutoff frequencies. After a careful examination, we found that the total power flow turns out to be simply zero.
We first propose the genetic algorithms (GA) to deal with strictly non-blocking grooming problems in optical tree
networks. We describe strictly non-blocking grooming problems in Wavelength Division Multiplexing (WDM) optical
trees with traffics and find the lower and upper bounds. Here we use the (μ + λ)-strategy to produce offspring for the
genetic algorithm, and apply the technology of wavelengths-reuse in the decoding of the individual in the genetic
algorithms. The performance of the proposed strictly non-blocking grooming algorithm was tested in tree networks with
different granularity and different number of traffic patterns. Computer simulation results show that our algorithm can
achieve very good results in saving both ADM's and wavelength in tree networks.
Some research results on tunable fiber gratings and their applications are presented in this paper. Dynamic characteristics of thermal tuned FBG by surface coated heater are described. Tuning characteristics and effects of friction in compression tuning packaging are analyzed. Tuning behaviors of LPG in Panda fiber are described and discussed. A pressure sensor by LPG is presented. And demodulation for sensor systems by using tunable FBG is proposed.
this paper, the strain and temperature responses of long-period Bragg grating written on Panda fiber are presented. Both the strain and temperature responses show a good linear characteristics at a strain range of 0-2500 ?? and a temperature range of 50-100 °C . The temperature-tuning characteristics of the LPG by using a thin film metal coating on the nude surface of the fiber as a heater are also demonstrated. In the range of 0- 150 mA the response curve of the LPG have good linearity with the square of the current, while the loss change is less than 0.3dB.
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