The cross-beam method has been used in calculations of load distribution, flow velocity, ultrasonic speed, and so on. This paper shows that the method is also mostly feasible to be utilized in optics-based measurement of suspended solids in liquid. We present a prototype of a measurement probe that has a set of two near-infrared emitter–receiver pairs and employs the cross-beam method. Our laboratory experiments, focused on measurements of H₂O−SiO₂ solid solution, show that the developed probe has good sensitivity and can linearly measure the concentration of suspended solids with a wide dynamic range. The presented prototype is suitable for a broad range of applications. In particular, we demonstrate its suitability for monitoring sedimentation in water.

A hybrid optical fiber structure sensor for simultaneous measurement of temperature and low pressure based on Fabry–Perot (FP) interference and fiber Bragg grating (FBG) is proposed. The FP cavity is fabricated with a capillary pure silica tube, whose one end is surface processed to result in an open FP cavity. The measurement of refractive index change of different pressures has been achieved by monitoring the wavelength shift of the interference pattern in the reflection spectrum. The FP cavity is integrated with the FBG to obtain temperature measurement simultaneously.

This PDF file contains the editorial “Special Section Guest Editorial:2-D Materials for Optics and Photonics” for OE Vol. 55 Issue 08

We report on the structural investigation of self-organized assemblies of PbS nanocrystals (NCs) of different sizes, which were deposited on a glass substrate or embedded in a porous matrix. Regardless of the NC size and the type of the substrate and matrix, the assemblies were ordered in two-dimensional superlattices with densely packed NCs.

We report on the first experimental study of the layer-to-layer compression and enhanced optical properties of few-layer graphene nanosheet by applying ion irradiation. The deformation of graphene layers is investigated both theoretically and experimentally. It is observed that after the irradiation of energetic ion beams, the space between separate graphene layers is reduced due to layer-to-layer compression, resulting in tighter contact of the graphene sheet with the surface of the substrate. This processing enables enhanced interaction of the graphene with the evanescent-field wave near the surface, which induces reinforced polarization-dependent light absorption of the graphene. Utilizing the ion-bombarded graphene nanosheets as saturable absorbers, we have realized efficient Q-switched waveguide lasing with enhanced performance through the interaction of the graphene and evanescent field.

The uniform-quality, large-area, monolayer graphene saturable absorber (SA) with sandwich structure was fabricated, tested, and successfully applied for the generation of diode-pumped Yb:Y₂SiO₅ mode-locked laser. Without extra negative dispersion elements, the shortest pulse with duration of ∼883 fs was obtained at 1042.6 nm with an output power of ∼1  W. These promising experimental results suggested that the low-cost, high-quality graphene SA could potentially be employed in practical, high-power, ultrafast mode-locking laser systems.

We experimentally demonstrated a laser diode-pumped Q-switched Nd:GdTaO₄ crystal laser at 1066 nm using a multilayer graphene oxide as the saturable absorber (GOSA). The GOSA is fabricated by transferring the liquid-phase-exfoliated GO nanosheets onto a K9 glass substrate. When the GOSA was inserted into the plano–plano laser cavity, a stable Q-switched laser operation is achieved with a maximum average output power of 0.382 W and repetition rate of 362 kHz. The shortest pulse duration is 194 ns and the single pulse energy is about 1.05 μJ.

We report a tungsten diselenide (WSe₂) polyvinyl alcohol (PVA)-based, saturable absorber and related experiment results of a Q-switched fiber laser. WSe₂-PVA film is synthesized by liquid phase exfoliation method, and its saturable absorption is measured via a nonlinear transmission experiment. The result shows that WSe₂-PVA saturable absorber has a modulation depth of 3.5%, which means it has potential for generating an ultrafast pulse laser. We apply this absorber into a ring-cavity erbium-doped fiber laser and obtain Q-switched pulses under appropriate pump power. Our work demonstrates the reliable nonlinear optical characteristics of WSe₂ and the feasibility for this two-dimensional material to be applied in the field of nonlinear optics.

We have experimentally demonstrated a passively Q-switched Tm-doped YAG ceramic laser with black phosphorus (BP) as saturable absorber (SA). According to the measurement, the BP saturable absorber mirror has a modulation depth of 5% and a saturation fluence of 20  μJ/cm². The generated Q-switched pulse has a maximum average power of 38.5 mW and pulse energy of 3.32  μJ, with the corresponding repetition rate of 11.6 KHz and pulse width of 3.12  μs at 2  μm wavelength. The results show that BP is a promising SA for midinfrared-pulsed lasers.

We demonstrated a pulsed erbium-doped fiber laser (EDFL) based on a few-layer molybdenum disulfide saturable absorber (MoS₂-SA). The MoS₂-SA was fabricated into a film structure by evaporating the mixture of MoS₂ nanosheets and polyvinyl alcohol. The Raman spectra and nonlinear optical characteristics were measured to confirm the quality of the as-prepared MoS₂-SA. By inserting the MoS₂-SA into an EDFL, the pulsed operation from the stable Q-switched to mode-locking regime could be achieved by simply increasing the pump power level. The Q-switched pulse duration and repetition rate could vary from 5.18 to 3.53  μs and from 72.74 to 86.39 kHz, respectively. The maximum pulse energy was 74.93 nJ. After the achievement of Q-switched operation, the ultrashort mode-locking pulse was obtained by further increasing the pump power. The results further demonstrate the excellent saturable absorption ability of the few-layer MoS₂ at telecommunication waveband.

We experimentally demonstrate that a bulk-structured Bi₂Te₃ topological-insulator (TI)-based saturable absorber can be used with a dissipative soliton resonance based, nanosecond-pulse fiber laser. Our results show that temporal width-tunable, mode-locked pulses can readily be produced through the dissipative soliton resonance effect from an erbium-doped fiber ring cavity into which a bulk-structured Bi₂Te₃ TI-deposited, side-polished fiber has been incorporated. The temporal width of the output pulses was changeable from 2.7 to 12.8 ns with an increasing pump power, and the corresponding pulse energy increased linearly from 4.7 to 22.4 nJ. This paper reaffirms that a bulk-structured Bi₂Te₃ TI can be used as an effective material for saturable absorption, and that the material is readily applicable for different types of mode-locked fiber lasers.

We report graphene mode-locked or Q-switched Tm/Ho-codoped fiber laser pumped by a 1212-nm phosphorus-doped fiber Raman laser. First, comparison experiments were performed for a continuous-wave 2  μm Tm/Ho-codoped fiber laser pumped by a 1565-nm laser or a 1212-nm laser, verifying that the 1212-nm pumping is more efficient than the conventional ∼1560-nm pumping. Then, we further realized 1212-nm highly efficient pumped Tm/Ho-codoped fiber lasers mode-locked and Q-switched by a graphene saturable absorber, respectively. Using only 30-cm Tm-Ho gain fiber under the 1212-nm pumping, the passive Q-switching at a center wavelength of 1976 nm was efficiently generated with tunable repetition rate between 32.2 and 43.0 kHz and shortest pulse width of 1.41  μs. Moreover, the passive mode-locking at 1913.7 nm was stably achieved with a fundamental repetition rate of 19.978 MHz and pulse energy of ∼20  pJ. To the best of our knowledge, it is the first demonstration of 2-μm pulsed fiber lasers high efficiently pumped by a 1212-nm laser.

We demonstrate the generation of dissipative soliton in an all-normal dispersion passively mode-locked ytterbium-doped fiber laser using few-layer molybdenum diselenide (MoSe²) as a saturable absorber. By adopting the cost-effective liquid phase exfoliation approach, few-layer MoSe² nanosheets are exfoliated and mixed with polyvinyl alcohol (PVA) to prepare a free-standing MoSe²-PVA film. The developed film is attached between two fiber ferrules to make a fiber compatible saturable absorber device. By incorporating this saturable absorber in an all-normal dispersion laser cavity, a stable dissipative soliton with a pulse width of 471 ps and 3-dB bandwidth of 4.26 nm centered at 1040 nm is generated. The fundamental repetition rate and the average power are measured as 15.44 MHz and 2 mW, respectively. To the best of our knowledge, this is the first demonstration of a dissipative soliton generation in 1  μm wavelength region using few-layer MoSe² saturable absorber. These results exhibit the significant potential of MoSe²-based saturable absorber in the near-IR region for all-fiber mode-locked lasers.

We demonstrate a passively Q-switched Yb³⁺-dopedScBO₃ bulk laser using a black phosphorous (BP) saturable absorber, a two-dimensional semiconductor. The response spectra of BP show that it is suitable as a universal switcher in the spectral range from the visible to midinfrared band. Considering the saturable absorption properties of BP and emission properties of Yb³⁺-doped crystals, the passively Q-switched bulk laser pulses were realized with the Yb³⁺:ScBO₃ crystal as a gain material and a fabricated BP sample as a Q-switcher. Because of the large energy storage capacity of Yb³⁺:ScBO₃, the maximum output energy is obtained to be 1.4  μJ, which is comparable with the previous reported maximum energy of graphene Q-switched lasers. The obtained results identify the potential capability of BP as a pulse modulator in bulk lasers, and BP plays an increasingly important role in a wide range of its applications, including photonics and optoelectronics.

As a unique type of driving force, the transverse optical gradient force has been extensively studied and applied in the nanowaveguides resonator. Recently, it is demonstrated that the optical forces in slot waveguides of hyperbolic metamaterials can be over two orders of magnitude stronger than that in conventional dielectric slot waveguides. To investigate the nonlinear dynamic characteristic of hyperbolic waveguide resonator driven by optical gradient force, a continuum elastic model of the optoresonator is presented and analytically solved using the methods of Rayleigh–Ritz and multiple scales. The results show that the optical force is strengthened with the increase of the filling ratio of silver in the hyperbolic waveguide. The resonance frequency becomes greater with the increase of the filling ratio of silver no matter what the geometric parameters and physical property parameters are. However, the steady maximum vibration amplitude becomes smaller, and the degree of system stiffness softening also reduces.

We have investigated the broadband saturable absorption property of graphene–Bi₂Te₃ heterostructures and demonstrated their applications for stable harmonic mode-locking operation in a Yb-doped fiber laser and wavelength-tunable Q-switching operation in an Er-doped fiber laser. The modulation depth of a graphene–Bi₂Te₃ heterostructure saturable absorber (G-Bi₂Te₃-SA) is dependent on the coverage of Bi₂Te₃ on the graphene. By using 15%-Bi₂Te₃-covered G-Bi₂Te₃-SA with a modulation depth of 23.28% and saturable intensity of 3.32  MW/cm², the harmonic mode-locked Yb-doped fiber laser outputs the mode-locked pulses with a pulse duration down to 189.94 ps, spectral bandwidth of 3.5 nm, and repetition rate of 79.13 MHz (21st order of the fundamental frequency). After inserting the G-Bi₂Te₃-SAwith 85% coverage of Bi₂Te₃ on graphene into Er-doped fiber laser cavity, whose modulation depth and saturable intensity are about 40.79% and 12.48  MW/cm², respectively, the wavelength-tunable Q-switched pulse with tunable wavelength range over 13.2 nm has been obtained by adjusting the intracavity fiber filter. These results suggest that the graphene–Bi₂Te₃ heterostructure could serve as a high nonlinear photonic device for practical applications.

We experimentally demonstrated a tunable triple-wavelength mode-locked erbium-doped fiber laser with few-layer topological insulator: Bi₂Se₃/polyvinyl alcohol solution. By properly adjusting the pump power and the polarization state, the single-, dual-, and triple-wavelength mode-locking operation could be stably initiated with a wavelength-tunable range (∼1  nm) and a variable wavelength spacing (1.7 or 2 nm). Meanwhile, it exhibits the maximum output power of 10 mW and pulse energy of 1.12 nJ at the pump power of 175 mW. The simple, low-cost triple-wavelength mode-locked fiber laser might be applied in various potential fields, such as optical communication, biomedical research, and sensing system.

We report on the generation of 152-nJ Q-switched pulses in all-polarization-maintaining Er-doped fiber laser. The laser is passively modulated by the antimony telluride (Sb₂Te₃) layer sputtered on a surface of the side-polished fiber in order to exploit the evanescent field interaction in optically nonlinear material. The laser cavity is designed in an extremely simple way comprising, in addition to fibers, only one component and the saturable absorber, forming a robust, compact, and stable source of short pulses. The repetition rate might be tuned from 42 kHz up to 132 kHz. The shortest recorded pulse duration was the 857 ns.

Black phosphorus (BP) is a very promising two-dimensional material as a saturable absorber for ultrashort pulse generation especially in telecommunication bands due to its ultrafast dynamic response and strong resonant absorption in the near-infrared wavelength range. However, the current fabrication methods of BP saturable absorbers are very complex and not suitable for practical large-scale production. We have successfully deposited BP with a thickness of ∼25  nm onto the fiber end facet as a saturable absorber by a simple optically driven deposition method. The BP saturable absorber shows excellent mode-locking performance with a stable pulse train repetition of 1.843 MHz and pulse duration of 117.6 ns.

We propose two schemes for achieving tungsten disulfide (WS₂)-based saturable absorber (SA) and saturable absorber mirror (SAM). By utilizing the pulsed laser deposition method, we grow the WS₂ film on microfiber to form an evanescent field interaction SA device. Incorporating this SA device into a common ring-cavity erbium-doped fiber (EDF) laser, stably passive mode-locking can be achieved with pulse duration of 395 fs and signal-to-noise ratio of 64 dB. We also produce a fiber tip integrated WS₂ -SAM by utilizing the magnetron sputtering technique (MST). This new type of SAM combines the WS₂ layer as SA and gold mirror as high reflective mirror. By employing the WS₂ -SAM, we construct the linear-cavity EDF lasers, and achieve passive mode-locking operation with pulse duration of ∼1  ns and SNR of ∼61  dB. We further achieve stably passive Q-switching operation with pulse duration of ∼160  ns and pulse energy of 54.4 nJ. These fiber-integrated SAs and SAMs have merits of compactness and reliability, paving the way for the development of new photonic devices such as SAs for pulsed laser technology.

Microlenses and microlens arrays are assuming an increasingly important role in optical devices and communication systems. In response to their extended use in different fields of technology, a great emphasis is being placed on research into simple manufacturing approaches for these micro-optical components as well as on the characterization of their performance. This paper provides an overview of the recent emerging technologies for the fabrication of polymer microlenses by electrical, mechanical, chemical, and pyro-electrical methods. Attention is mainly focused on polymer molding and self-assembling for microlens arrays, while ink-jet printing is proposed for on-demand printing of lenses with high resolution. Among all the emerging techniques proposed, the pyro-electrodynamic approach has recently achieved great interest as an easy multiscale approach for the fabrication of polymer microlens arrays through a flexible process driven by electrohydrodynamic pressure. As each processing method has distinct advantages and limitations, the most significant characteristic parameters and the measurements of these parameters are discussed for each method.

Spectral target detection refers to the process of searching for a specific material with a known spectrum over a large area containing materials with different spectral signatures. Traditional target detection methods in hyperspectral imagery (HSI) require assuming the data fit some statistical or geometric models and based on the model, to estimate parameters for defining a hypothesis test, where one class (i.e., target class) is chosen over the other classes (i.e., background class). Nonlinear manifold learning methods such as Laplacian eigenmaps (LE) have extensively shown their potential use in HSI processing, specifically in classification or segmentation. Recently, Schroedinger eigenmaps (SE), which is built upon LE, has been introduced as a semisupervised classification method. In SE, the former Laplacian operator is replaced by the Schroedinger operator. The Schroedinger operator includes by definition, a potential term V that steers the transformation in certain directions improving the separability between classes. In this regard, we propose a methodology for target detection that is not based on the traditional schemes and that does not need the estimation of statistical or geometric parameters. This method is based on SE, where the potential term V is taken into consideration to include the prior knowledge about the target class and use it to steer the transformation in directions where the target location in the new space is known and the separability between target and background is augmented. An initial study of how SE can be used in a target detection scheme for HSI is shown here. In-scene pixel and spectral signature detection approaches are presented. The HSI data used comprise various target panels for testing simultaneous detection of multiple objects with different complexities.

We are concerned with tracking an object of interest in a video stream. We propose an algorithm that is robust against occlusion, the presence of confusing colors, abrupt changes in the object features and changes in scale. We develop the algorithm within a Bayesian modeling framework. The state-space model is used for capturing the temporal correlation in the sequence of frame images by modeling the underlying dynamics of the tracking system. The Bayesian model averaging (BMA) strategy is proposed for fusing multiclue information in the observations. Any number of object features is allowed to be involved in the proposed framework. Every feature represents one source of information to be fused and is associated with an observation model. The state inference is performed by employing the particle filter methods. In comparison with the related approaches, the BMA-based tracker is shown to have robustness, expressivity, and comprehensibility.

This article presents a semifragile color image watermarking technique for content authentication. The proposed technique can be implemented with color images and embeds a watermarking sequence into the low-frequency coefficients of the approximation, horizontal, and vertical sub-bands of a modified two-leveled discrete wavelet transform. This is obtained by inserting a predefined value, collected from two of the three R, G, and B color layers, into the third color layer. This gives an ability to monitor modifications by observing the changes occurring in the color layer where the watermark is embedded. Here, two measures were developed to check the technique copyright and authentication performances. Experimental results have shown a high accuracy in detecting and localizing intentional attacks while exhibiting a high robustness against common image processing attacks.

This study proposes a hybrid of a recurrent fuzzy cerebellar model articulation controller (RFCMAC) and a weighted strategy for solving single-image visibility in a degraded image. The proposed RFCMAC model is used to estimate the transmission map. The average value of the brightest 1% in a hazy image is calculated for atmospheric light estimation. A new adaptive weighted estimation is then used to refine the transmission map and remove the halo artifact from the sharp edges. Experimental results show that the proposed method has better dehazing capability compared to state-of-the-art techniques and is suitable for real-world applications.

Imaging of physically inaccessible parts of the body such as the colon at micron-level resolution is highly important in diagnostic medical imaging. Though flexible endoscopes based on the imaging fiber bundle are used for such diagnostic procedures, their inherent honeycomb-like structure creates fiber pixelation effects. This impedes the observer from perceiving the information from an image captured and hinders the direct use of image processing and machine intelligence techniques on the recorded signal. Significant efforts have been made by researchers in the recent past in the development and implementation of pixelation removal techniques. However, researchers have often used their own set of images without making source data available which subdued their usage and adaptability universally. A database of pixelated images is the current requirement to meet the growing diagnostic needs in the healthcare arena. An innovative fiber pixelated image database is presented, which consists of pixelated images that are synthetically generated and experimentally acquired. Sample space encompasses test patterns of different scales, sizes, and shapes. It is envisaged that this proposed database will alleviate the current limitations associated with relevant research and development and would be of great help for researchers working on comb structure removal algorithms.

Dictionary learning has previously been applied to target tracking across images in video sequences. However, most trackers that use dictionary learning neglect to make optimal use of the representation coefficients to locate the target. This increases the possibility of losing the target in the presence of similar objects, or in case occlusion or rotation occurs. We propose an effective object-tracking method based on a double-dictionary appearance model under a particle filter framework. We employ a double dictionary by training template features to represent the target. This representation not only exploits the relationship between the candidate and target but also represents the target more accurately with minimal residual. We also introduce a simple and effective strategy to update the template to reduce the influence of occlusion, rotation, and drift. Experiments on challenging sequences showed that the proposed algorithm performs favorably against the state-of-the-art methods in terms of several comparative metrics.

Cross-spectral image matching is a challenging research problem motivated by various applications, including surveillance, security, and identity management in general. An example of this problem includes cross-spectral matching of active infrared (IR) or thermal IR face images against a dataset of visible light images. A summary of recent developments in the field of cross-spectral face recognition by the authors is presented. In particular, it describes the original form and two variants of a local operator named composite multilobe descriptor (CMLD) for facial feature extraction with the purpose of cross-spectral matching of near-IR, short-wave IR, mid-wave IR, and long-wave IR to a gallery of visible light images. The experiments demonstrate that the variants of CMLD outperform the original CMLD and other recently developed composite operators used for comparison. In addition to different IR spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated. Performance of CMLD I to III is evaluated for each of the three cases of distances. The newly developed operators, CMLD I to III, are further utilized to conduct a study on cross-spectral partial face recognition where different facial regions are compared in terms of the amount of useful information they contain for the purpose of conducting cross-spectral face recognition. The experimental results show that among three facial regions considered in the experiments the eye region is the most informative for all IR spectra at all standoff distances.

A remote eye-gaze tracking (REGT) method is presented, which compensates for the error caused by device rotation. The proposed method is based on the state-of-the-art homography normalization (HN) method. Conventional REGT methods, including the HN method, suffer from a large estimation error in the presence of device rotation. However, little effort has been made to clarify the relation between the device rotation and its subsequent error. This paper introduces two factors inducing device rotation error, the discrepancy between the optical and visual axis, called angle kappa, and the change in camera location. On the basis of these factors, an efficient method for compensating for the REGT error is proposed. While the device undergoes a 360-deg rotation, a series of erroneous points of gaze (POGs) are obtained on the screen and modeled as an ellipse, and then the center of the ellipse is exploited to estimate the rotation-invariant POG. Experimental results demonstrate that the proposed REGT method can estimate the POG accurately in spite of the rotational movement of the device.

In the float glass defect inspection system based on machine vision, the common defects can be detected and classified correctly. However, the online glass ream inspection is still a problem to be solved, and the accuracy cannot fulfill the requirement of glass grading. As the glass ream is a rather slight optical distortion in most cases, it should be amplified so that it can be checked out easily. A Moiré method based on the theory of superposition shadow is proposed, which can magnify the distortion effectively without increasing the system complexity, and a STFT method is presented to analyze the distortion according to the characteristics of Moiré fringe pattern. With this method, the vision interference angle of glass ribbon can be calculated out accurately in real time, which makes it suitable for online glass ream inspection.

An online fringe projection profilometry (OFPP) based on scale-invariant feature transform (SIFT) is proposed. Both rotary and linear models are discussed. First, the captured images are enhanced by “retinex” theory for better contrast and an improved reprojection technique is carried out to rectify pixel size while keeping the right aspect ratio. Then the SIFT algorithm with random sample consensus algorithm is used to match feature points between frames. In this process, quick response code is innovatively adopted as a feature pattern as well as object modulation. The characteristic parameters, which include rotation angle in rotary OFPP and rectilinear displacement in linear OFPP, are calculated by a vector-based solution. Moreover, a statistical filter is applied to obtain more accurate values. The equivalent aligned fringe patterns are then extracted from each frame. The equal step algorithm, advanced iterative algorithm, and principal component analysis are eligible for phase retrieval according to whether the object moving direction accords with the fringe direction or not. The three-dimensional profile of the moving object can finally be reconstructed. Numerical simulations and experimental results verified the validity and feasibility of the proposed method.

This work proposes a point-specific self-calibration method to characterize film thickness distribution by exploiting the multiple detection capability of a home-built full-field ellipsometer. The self-calibration method offers a feasible route for retrieving calibration information from the actual real-time sample measurement in conjunction with the ellipsometric parameters, thus leading to error-free data after the elimination of systematic errors and addressing the problem of high time-consumption. With the help of the multiple detection capability of a full-field ellipsometer, we can further implement self-calibration for every point-specific pixel, termed as point-specific self-calibration to achieve a high-accuracy film thickness profile. The synthetic thickness distribution composed of structural-anisotropy pixels with tilted surface is utilized to demonstrate the potential of the proposed approach by retrieving the ellipsometric angles and the calibration parameters of every single pixel. A three orders-of-magnitude improvement in the accuracy of thickness determination was achieved in the simulation. To demonstrate the feasibility of the proposed approach, a SiO₂ film deposited on the Si substrate is measured in this work. This approach could be easily extended to implement thickness distribution measurements accurately and rapidly in other rotating-element ellipsometer cases.

Measurement of tilt plays an important role in metrological applications and consequently, several methods have been proposed in the recent past. Classical interferometric methods can measure angles with high accuracy but are easily susceptible to external turbulences. We propose to use a cyclic interferometer to measure tilt in which the sensitivity to tilt measurement is double when compared with that of the classical Michelson interferometer. Since the counter propagating beams travel identical paths, the interferometer is insensitive to external vibrations and turbulence and thus can be used under harsh environmental conditions. The novelty in the technique lies in creating multiple reflections in the tilt mirror to enhance the measurement accuracy by the way of increasing the sensitivity. This paper presents the basics of the interferometer and experimental results to quantify the increase in sensitivity. By increasing the number of reflections, it is shown that sensitivity can be further improved to measure tilt angles below 5  μ rad.

We describe a computer simulation technique for generating the monochromatic light diffraction from arbitrary apertures. For the Fresnel diffraction of rectangular and circular apertures, a simple form of equation for the light intensity distribution is derived. A method for displaying the color of monochromatic light on the monitor is presented. On this basis, we implement the diffraction simulation of white light formed via mixing three monochromatic lights of λ=700,546.1,435.8  nm with the same ratio in the RGB color space of CIE1931 system.

We propose a simple method to compute the first higher order mode cutoff frequency of a single-mode fiber in the presence of optical nonlinearity. We consider optical Kerr-type nonlinearity for these fibers having dispersion-shifted and dispersion-flattened profiles. Our analysis involves the Chebyshev method but introduces a linearization of cubic terms of fields due to Kerr-type nonlinearity. Our results are shown to match excellently with the available exact numerical values. Thus, this formulation and stepwise algorithm should be considered as a simple but accurate alternative to deeply involved numerical technique and used as a guideline in calculating and minimizing the modal noise in single-mode nonlinear fibers.

To self-calibrate the intrinsic camera parameters, we designed a calibration pattern and proposed a method to estimate camera parameters involving distortion coefficients from orthogonal vanishing points. We first obtained four pairs of vanishing points from an image of the calibration pattern and selected the two pairs with the smallest error. Then, after analyzing the effect of the intrinsic parameter error from the noise of the vanishing points, we employed an optimization algorithm to obtain the best vanishing points. Using two images with different orientations, we could obtain the intrinsic parameters by using a linear method. Finally, according to the preliminary calibrated intrinsic parameters and a criterion that the airline is a static straight line in the pictorial plane, the arithmetic mean of the camera distortion, which is based on the common characteristic points, could be obtained. Simulated and experimental results indicated that the two-dimensional reconstruction error is 0.32 pixels. Although this method has the same error level as the traditional method, it has a better flexibility and can achieve real-time camera self-calibration.

Although the optimization of a static Fabry–Perot interferometer (FPI)—used as a Doppler shift discriminator in wind lidar—has been proposed, it cannot be applied to the scanning FPI used in the high-spectral resolution lidar for temperature detection. After a comparison, the optimal scanning implementation is chosen and a new optimization scheme is proposed. The free spectral range (FSR) of the FPI is determined by the width of the Rayleigh spectrum. Then, for analytical purposes, the transmission of Rayleigh backscattering through an FPI is simplified to be a superposition of a Gaussian function and a constant background. The maximum likelihood estimation and the Cramer–Rao bound theory are used to derive an analytic expression of the temperature error. Thus, the effective reflectance of the FPI can be optimized. Finally, assuming known atmospheric temperature–pressure–density profiles, backscattering raw signals are simulated using the optimized parameters of the FPI and some other key system parameters of our existing lidar system. Comparisons between the assumed and retrieved temperature profiles revealed that error <2  K can be achieved in the altitude range of 15 to 40 km, even with the disturbance of aerosol contamination.

In the context of carrying a wide variety of modulation formats and data rates for home networks, the study covers the radio-over-fiber (RoF) technology, where the need for an alternative way of management, automated fault diagnosis, and formats identification is expressed. Also, RoF signals in an optical link are impaired by various linear and nonlinear effects including chromatic dispersion, polarization mode dispersion, amplified spontaneous emission noise, and so on. Hence, for this purpose, we investigated the sampling method based on asynchronous delay-tap sampling in conjunction with a cross-correlation function for the joint bit rate/modulation format identification and optical performance monitoring. Three modulation formats with different data rates are used to demonstrate the validity of this technique, where the identification accuracy and the monitoring ranges reached high values.

A color mixing light-emitting diode (LED) light engine that can replace 2-kW halogen–Fresnel spotlight with high-luminous flux in excess of 20,000 lm is reported for applications in professional stage and studio lighting. The light engine focuses and mixes the light from 210 LEDs of five different colors through a microlens array (MA) at the gate of Ø50  mm. Hence, it produces homogeneous color-mixed tunable white light from 3000 to 6000 K that can be adjustable from flood to spot position providing 10% translational loss, whereas the corresponding loss from the halogen–Fresnel spotlight is 37%. The design, simulation, and optimization of the light engine is described and compared to the experimental characterization of a prototype. The light engine is optimized through the simulated design of reflector, total internal reflection lens, and MA, as well as the number of LEDs. An optical efficiency of 59% and a luminous efficacy of 33  lm/W are achieved, which is three times higher than the 2-kW halogen–Fresnel spotlight. In addition to having color rendering of color rendering index R_a > 85 and television lighting consistency index 12 > 70, the dimmable and tunable white light can be color controlled during the operational time.

Photoacoustic (PA) imaging is a modality for achieving high-contrast images of blood vessels or tumors. Most PA imaging systems use complex reconstruction algorithms under conventional linear array transducers. We introduced the optical simulating method to improve the acoustic lens design and obtain a PA imaging system with improved spatial revolution (a 0.5-mm point spread function and a lateral image resolution of more than 1 mm) is realized using a 4f aspherical acoustic lens. The acoustic lens approach improved the image resolution and enabled direct reconstruction of three-dimensional (3-D) PA images. The system demonstrated a lateral resolution of more than 1 mm, a field of view of 8.5 deg, and a depth of focus of 10 mm. The system displays great potential for developing a real-time 3-D PA camera system for biomedical ultrasound imaging applications.

We developed a fabrication method for remote phosphor by a screen-printing process, using green phosphor, red phosphor, and thermally stable glass frit. The glass frit was introduced for long-term stability. The optical properties of the remote phosphor were observed via an integrating sphere; the photoluminescence spectrum dramatically changed on incorporating a minor amount of the red phosphor. These unique optical properties were elucidated using four factors: phosphor ratio, scattering induced by packing density, light intensity per unit volume, and reabsorption. The thermal stability of the remote phosphor was investigated at 500°C, demonstrating its outstanding thermal properties.

This paper describes a Fourier propagator for computing the impulse response of an optical system, while including terms ignored in Fresnel and Fraunhofer calculations. The propagator includes a Rayleigh–Sommerfeld diffraction formula calculation from a distant point through the optical system to its image point predicted by geometric optics. The propagator then approximates the neighboring field points via the traditional binomial approximation of the Taylor series expansion around that field point. This technique results in a propagator that combines the speed of a Fourier transform operation with the accuracy of the Rayleigh–Sommerfeld diffraction formula calculation and extends Fourier optics to cases that are nonparaxial. The proposed propagator facilitates direct calculation of aberration coefficients, making it more versatile than the angular spectrum propagator. Bounds on the phase error introduced by the approximations are derived, which show that it should be more widely applicable than the Fresnel propagator. Guidance on how to sample the pupil and detector planes of a simulated imaging system is provided. This report concludes by showing examples of diffraction calculations for a laboratory setup and comparing them to measured diffraction patterns to demonstrate the utility of the propagator.

Diffraction effects play a significant role in scene projectors by digital micromirror devices (DMDs) in the long-wave infrared (IR) band (8 to 12 μm). The contrast provided by these projector systems can become noticeably worse because of the diffraction characteristics of the DMD. The actual diffraction characteristics of the DMD deviate significantly from the predictions of scalar diffraction theory in the long-wave IR. To address this issue, we built a vector diffraction-grating model of the DMD; the diffraction grating model is simulated with MATLAB. Furthermore, we analyze the effect of incident angle and polarization, which are the main factors that decrease the contrast of DMD-based scene projectors in the long-wave IR. Finally, an effective method to improve the contrast of the scene projector system is given, and the maximum contrast of the scene projector system is ∼0.7.

Laser beam shaping at focus or focal beam shaping is essential for many applications. The most common approach makes use of the Fourier transforming properties of lenses to generate at their focal planes the desired irradiance patterns, e.g., the flattop. There are two inherent limitations for this approach. First, the shaping quality depends strongly on the dimensionless parameter β. In the case of a long focal length or small beam sizes giving a small β value, additional beam expanders are needed to achieve a satisfying irradiance pattern at the focus. Second, without considering the phase, the irradiance patterns beyond the focal plane are not controlled. We propose a different approach with two plano-aspheric lenses that allow control of both irradiance and phase at focus. The design method comprises an extended ray mapping procedure combined with backward wave propagation from focus. With this design approach, the shaping quality is guaranteed without the possible need for extra beam expanders, offering the potential for a more compact system with fewer elements. Through the additional phase control, the depth of focus is enlarged to a large extent and the designed system becomes more tolerant.

A scheme for optical parallel encryption/decryption of quadrature phase shift keying (QPSK) signals is proposed, in which three QPSK signals at 10  Gb/s are encrypted and decrypted simultaneously in the optical domain through nondegenerate four-wave mixing in a highly nonlinear fiber. The results of theoretical analysis and simulations show that the scheme can perform high-speed wiretapping against the encryption of parallel signals and receiver sensitivities of encrypted signal and the decrypted signal are −25.9 and −23.8  dBm, respectively, at the forward error correction threshold. The results are useful for designing high-speed encryption/decryption of advanced modulated signals and thus enhancing the physical layer security of optical networks.

With urgent demand for an integrated information network and development of free-space laser communication technology, research on high-rate laser communication networking technology is vital. This study analyzed the technical difficulties related to space laser communication networking and proposed a laser communication networking solution. A wide-angle beam expander and dual-rotating prism group were incorporated into a multiaccess optical laser communication antenna. The wide-angle beam expander collects signal light from different directions; the dual-rotating prism group tracks different targets simultaneously. This paper presents an overall scheme allowing multiaccess free-space laser communications based on the optical antenna described and the associated relay optics and transceiver subsystems.

This paper presents a performance analysis and comparison of optimized multipump Raman and hybrid erbium-doped fiber amplifier (EDFA) + Raman amplifiers, operating simultaneously at conventional (C) and long (L) bands, using multiobjective optimization based on evolutionary elitist nondominated sorting genetic algorithm. The amplifiers performance was measured in terms of on–off gain, ripple, optical signal-to-noise ratio (OSNR) and noise figure (NF), after propagating over 90 and 180 km of single-mode fiber (SMF). Numerical simulation results of the first analysis show that only three pumps are necessary to generate optimal gains in both amplifiers. Comparing the results of the second performance analysis, we conclude that, after 90 km SMF, the two amplifiers has the same on–off gain, if the total pump power (1807.1 mW) of the Raman amplifier is approximately double (100+994.7  mW) of the hybrid amplifier, when the EDFA is operating at 1480 nm with 5 m of doped fiber. Furthermore, the Raman amplifier needs a single laser with at most 741.1 mW, against 343.9 mW of the distributed Raman amplifier (DRA) pump in the hybrid system. Finally, the results of the last analysis, which considers only the EDFA + Raman amplifier, shows that with on–off gain of 26.14 dB, ripple close to 1.54 dB over a bandwidth of 66 nm and using three pumps lasers in the DRA the achieved OSNR was 39.6 dB with an NF lower than 3.3 dB, after 90 km of SMF.

Spatial domain multiplexing (SDM), also known as space division multiplexing, adds a new degree of photon freedom to existing optical fiber multiplexing techniques by allocating separate radial locations to different channels of the same wavelength as a function of the input launch angle. These independent MIMO channels remain confined to their designated locations while traversing the length of the carrier fiber owing to helical propagation of light inside the fiber core. As a result, multiple channels of the same wavelength can be supported inside a single optical fiber core, thereby allowing spatial reuse of optical frequencies and multiplication of fiber bandwidth. It also shows that SDM channels of different operating wavelengths continue to follow an output pattern that is based on the input launch angle. As a result, the SDM technique can be used in tandem with wavelength division multiplexing (WDM), to achieve higher optical fiber bandwidth through increased photon efficiency and added degrees of photon freedom. This endeavor presents the feasibility of a hybrid optical fiber communication architecture in which the spectral efficiency of the combined system increases by a factor of “n” when each channel of an “n” channel SDM system carries the entire range of WDM spectra.

Previous research on achieving the alignment of compression gratings has mainly focused on the parallelism of the gratings. We propose a promising method to achieve parallelism and especially accurately adjust the grating to its optimum working angle to achieve dispersion compensation. A spectrometer and a precisely adjustable mirror pair are cooperatively used to measure the wavelength of the light diffracted by the grating, satisfying the Littrow condition. Meanwhile, the tiny slit of the spectrometer can decrease the grating-tip and in-plane rotation error during the alignment procedure. Using this technique, the residual phase of the compressed pulse is optimized and the compressed pulse duration is 25.4 fs, which is 1.06 times that of the Fourier-transform-limited compressed pulse.

A midinfrared (mid-IR) saturable absorber mirror (SAM) was fabricated by coating aluminum film on Fe²⁺:ZnSe crystal, based on the vacuum evaporation method. By employing the prepared SAM, we demonstrated a high-power passively Q-switched Er³⁺-doped ZrF₄-BaF₂-LaF₃-AIF₃-NaF (ZBLAN) fiber laser at 2.8  μm. The highest output power in excess of 1.01 W was obtained with a pulse energy of 11.37  μJ and pulse duration of 0.73  μs, corresponding to a repetition rate of 88.84 kHz. To the best of our knowledge, these values represent the highest output power/pulse energy from a passively Q-switched ZBLAN fiber laser around 2.8  μm. Our results demonstrate that Fe²⁺:ZnSe SAM is a promising device for high-power/high-energy pulse generation in compact mid-IR fiber lasers.

The weight of rolling trucks on roads is one of the critical factors for the management of road networks due to the continuous increase in truck weight. Weigh-in-motion (WIM) sensors have been widely used for weight enforcement. A three-dimensional glass fiber-reinforced polymer packaged fiber Bragg grating sensor (3-D GFRP-FBG) is introduced for in-pavement WIM measurement at low vehicle passing speed. A sensitivity study shows that the developed sensor is very sensitive to the sensor installation depth and the longitudinal and transverse locations of the wheel loading position. The developed 3-D GFRP-FBG sensor is applicable for most practical pavements with a panel length larger than 6 ft, and it also shows a very good long-term durability. For the three components in 3-D of the developed sensor, the longitudinal component has the highest sensitivity for WIM measurements, followed by the transverse and vertical components. Field testing validated the sensitivity and repeatability of the developed 3-D GFRP-FBG sensor. The developed sensor provides the transportation agency one alternative solution for WIM measurement, which could significantly improve the measurement efficiency and long-term durability.

Network virtualization can eradicate the ossification of the infrastructure and stimulate innovation of new network architectures and applications. Elastic optical networks (EONs) are ideal substrate networks for provisioning flexible virtual optical network (VON) services. However, as network traffic continues to increase exponentially, the capacity of EONs will reach the physical limitation soon. To further increase network flexibility and capacity, the concept of EONs is extended into the spatial domain. How to map the VON onto substrate networks by thoroughly using the spectral and spatial resources is extremely important. This process is called VON embedding (VONE).Considering the two kinds of resources at the same time during the embedding process, we propose two VONE algorithms, the adjacent link embedding algorithm (ALEA) and the remote link embedding algorithm (RLEA). First, we introduce a model to solve the VONE problem. Then we design the embedding ability measurement of network elements. Based on the network elements’ embedding ability, two VONE algorithms were proposed. Simulation results show that the proposed VONE algorithms could achieve better performance than the baseline algorithm in terms of blocking probability and revenue-to-cost ratio.

We propose a bidirectional hybrid fiber-visible laser light communication (fiber-VLC) system. To reduce the cost of the system, the cheap and easy integration red vertical cavity surface emitting lasers, low-complexity carrier-less amplitude phase modulation format, and wavelength reuse technique are utilized. Meanwhile, the automatic gain control amplifier voltage and bias voltage for downlink and uplink are optimized. The simulation results show that, by using the proposed system, the bit error rate of 3.8×10⁻³ can be achieved for 16-Gbps CAP signal after 30-km standard single mode fiber and 8-m VLC bidirectional transmission. Therefore, it indicates the feasibility and potential of proposed system for indoor access network.

Time- and wavelength-division multiplexed passive optical networks (TWDM-PONs) have been selected by the full services access network community as the most suitable technology for next-generation optical access networks. A key technology in TWDM-PON is the colorless optical network unit transceiver. This paper proposes a flexible, tunable optical transceiver that uses directly modulated tunable lasers. Using a field-programmable gate array (FPGA), programmable reconfigurations and testing capabilities can be embedded into the transceiver in order to implement wavelength control, signal generation, pre-emphasis for upstream, and a bit error rate (BER) test for the downstream. To ensure high-quality signal generation at different bitrates, impedance matching between the laser driver circuit and the laser diodes is optimized. Using the proposed transceiver, three-section-distributed Bragg reflector tunable lasers at or below 2.5  Gb/s direct modulation through a 40-km standard mode fiber transmission were successfully implemented.

Semianalytic models are developed to deterministically calculate the variances of degenerate and nondegenerate four-wave mixing (FWM) noises for dispersion-managed dense wavelength division multiplexing (DWDM) systems with 8-Ary modulations [i.e., 8-level amplitude- and differential phase-shift keying (8APSK) and constant-amplitude optical differential 8-level phase-shift keying (D8PSK)]. The semianalytic models include various important propagation effects for exact numerical results. A 5.28-Tb/s (40-Gs/s/ch) 100-GHz-spaced 33-channel DWDM system with a dispersion map is then numerically analyzed by using the newly derived semianalytic models. It is numerically validated that FWM impacts coming from 8APSK pump channels are more severe than those coming from D8PSK ones, where pump channels denote the channels whose energies are transferred to a probe channel through the FWM process. The numerical results show that although FWM tolerance of a central channel with 8APSK is worse than that with D8PSK, a central channel with 8APSK is still superior to that with D8PSK when some linear noises and FWM noise are simultaneously taken into account for our given system conditions, which is mainly attributed to a relatively larger minimum Euclidean distance for the 8APSK constellation than the D8PSK one.

Thermal control of the volume Bragg grating (VBG) in the laser diode (LD) with the external cavity is critical for the tuning of the wavelength and the narrowing of the bandwidth. Based on finite element theories, thermal properties of the VBG were researched under different conditions of the LD illuminated area, laser power, gratings’ working temperature, and heat convection. Both the VBGs in the external cavity of the LD bar and stack were considered in the experiments. The results show that higher working temperature of the VBG and adopting better heat convection cooling methods are beneficial to realize the uniformity of the VBG temperature distribution.

We investigate an optical pulse-overlap transmission scheme where the orthogonal condition between neighbor pulses is violated. The interferences between the grouped optical pulses are mitigated at the optical coherent receiver with time diversity multiple-input and multiple-output-based digital signal processing. Numerical simulation investigates the performance of 50% return-to-zero (RZ)-quadrature phase-shift keying (QPSK) signals, where up to four pulses are overlapped and grouped for per pulse period. In the experiment demonstration, two 50% RZ-QPSK signals are combined with different time offset between neighbor pulses, and the Q-performance as a function of optical-signal-to-noise ratio (OSNR) is compared on each pulse channel basis, with minimum OSNR penalty of only 1-dB compared to the single pulse transmission.

We investigate the Kerr nonlinear optical processes (NOPs) in the case of a single-mode trapezoidal index fiber based on recently formulated and appropriate Marcuse-type relations for spot size in terms of normalized frequency corresponding to such fiber having various aspect ratios. With the help of these relations, we have analyzed the maximum NOP in these fibers having prospective the merits of tight light confinement in the subwavelength diameter waveguiding region. The comparative investigation reveals that the aspect ratio having a value of 0.7 is the most promising candidate for maximum optical nonlinearity, constructional convenience, and less diffraction. The analysis should be attractive for system users as a ready reference.

Although slot waveguide structures are widely used in all kinds of optical devices, very few articles focus on the issue of optical isolation of slot waveguides. This article, in an effort to bridge the gap in the available literature, focuses on the aspect of optical isolation of slot waveguides and provides definitive rules for application of different slot waveguides in dense integration of optical links. A slot waveguide with a 48-nm-wide slot was fabricated with electron beam lithography and inductively coupled plasma etching.

The effect of strain on civil structures is experimentally studied using fiber Bragg grating (FBG). The genetic algorithm is implemented to optimize the multiple parameters (Poisson’s ratio, photoelastic coefficient P₁₁, and photoelastic coefficient P₁₂) of the proposed sensor. The optimized results helped in increasing the sensitivity in terms of wavelength shift. It is observed that the proposed FBG provides maximum wavelength shift of 38.16 nm with Poisson’s ratio of 1.94, photoelastic coefficient P₁₁ of 1.994, and photoelastic coefficient P₁₂ of 1.8103.

Yb:YAG ceramic solid-state laser gain media have been of growing interest for high-repetition rate and high-power lasers during the last few years. A great advantage of ceramic technology compared with that of single crystals is the flexibility of shaping methods allowing the production of near-net-shape components with a well-defined internal structure. A favorable dopant distribution can enhance laser efficiency by mitigating thermal effects. The presented work reports on Yb:YAG transparent ceramics composed of layers with different Yb doping produced by two different shaping methods: dry pressing of spray-dried powders and tape casting, all sintered under high vacuum. The selected geometry of materials was based on numerical simulations. Optical quality of produced ceramics was characterized and discussed in connection with the microstructure and laser emission results. Output power of nearly 7 W and slope efficiency of 58.1% were obtained in quasi-continuous wave regime from bilayered 0% to 10% Yb:YAG. In the case of multilayered materials, higher scattering losses were observed. The comparison of the two processing methods highlighted that the tape-cast materials provided higher optical uniformity and the diffusion zone between the single layers with different dopant content was about 150  μm compared to about 250  μm in samples produced by pressing of powders.

We proposed and theoretically investigated a ring resonator-based traveling-wave electro-optic modulator integrated with asymmetric Mach–Zehnder interferometer (AMZI). The AMZI improved the modulation sensitivity and response of the modulator. A 2.93-fold increase in modulation sensitivity was achieved when compared with conventional Mach–Zehnder (MZ) modulators. A traveling-wave analysis of this modulator was presented for the first time. The simulation results showed that the modulator had superior performance compared to conventional ring modulators and MZ modulators. A modulation up to 275 GHz was achieved in the presence of both microwave loss and velocity mismatch.

Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10  mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6  nm at 10  mg/ml and a minimum shift of +27.24  nm at 1  mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

Two-dimensional (2-D) metal nanodot arrays (NDAs) have been attracting significant attention for use in biological and chemical sensing applications. The unique optical properties of the metal NDAs originate from their localized surface plasmon resonance (LSPR). Nanofabrication methods that use nanoporous alumina masks (NAMs) have been widely used to produce metal NDAs. We report a fabrication technique for a 2-D Ag NDA and its utilization as a platform for LSPR-based sensing applications. A well-ordered Ag NDA of ∼70-nm diameter, arranged in a periodic pattern of 105 nm, was fabricated on an indium tin oxide (ITO) glass substrate using an NAM as an evaporation mask. The LSPR of the Ag NDA on the ITO glass was investigated using ultraviolet–visible spectroscopy. The LSPR wavelength shifts caused by the variations in the quantity of methylene blue adsorbed on the Ag NDA were examined. The results of this study suggest that the Ag NDA prepared using NAM can be used as a chemical sensor platform.

A label-free optical microring resonator biosensor based on lithium niobate-on-insulator (LNOI) technology is designed and simulated for biosensing applications. Although silicon-on-insulator technology is quite mature over LNOI for fabricating more compact microring resonators, the latter is attractive for its excellent electro-optic, ferroelectric, piezoelectric, photoelastic, and nonlinear optic properties, which can offer a wide range of tuning facilities for sensing. To satisfy the requirement of high sensitivity in biosensing, the dual-microring resonator model is applied to design the proposed sensor. The transmission spectrum obtained from two-dimensional simulations based on finite-difference time-domain method demonstrates that the designed LNOI microring sensor consisting of a 10-μm outer ring and a 5-μm inner ring offers a sensitivity of ∼68  nm/refractive index unit (RIU) and a minimum detection limit of 10⁻² RIU. Finally, the sensor’s performance is simulated for glucose sensing, a biosensing application.

The concept of soliton provides a line in research in telecommunications systems. In the present study, a soliton all-optical logic AND gate with semiconductor optical amplifier (SOA)-assisted Mach–Zehnder interferometer has been numerically simulated and investigated. The dependence of the output quality factor (Q-factor) on the soliton characteristics and SOA parameters has been examined and assessed. The obtained results demonstrate that the soliton AND gate is capable of operating at a data rate of 80  Gb/s with logical correctness and high-output Q-factor.

Arrayed waveguide gratings (AWGs) are commonly used as multiplexers/demultiplexers in wavelength division multiplexing systems. We design and fabricate a coarse wavelength division multiplexing AWG with a wide free-spectral range. A gull-wing-shaped AWG layout and S-shaped AWG layout are used to understand a wide band range. The spectral difference between each layout is experimentally demonstrated. Our results indicate that the fabricated AWG is suitable for applications such as portable power meters.

This PDF file contains the errata for “OE Vol. 55 Issue 08 Paper OE-2016-0714-ERR” for OE Vol. 55 Issue 08