Optical Filters Research Papers - Academia.edu (original) (raw)

We analyze 20-Gb/s RZ-DQPSK transmission in a 33-GHz spaced 64-channel DWDM system over a 2000-km laboratory straight line. In particular filtering impact on DQPSK modulation format due to optical filter and a de-interleaver at the... more

- by
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- Computer Science, Physics, Optical Networks, Experimental Evaluation

Two-color laser systems based on a semiconductor laser device and spectrally filtered feedback are studied. By use of a broadband numerical simulator and realistic active-structure optical responses, various two-color lasing configurations are investigated. Five characteristic dynamic regimes are observed and classified as semicoherent, coherent, multimode, chaotic, and multimode chaotic. Practical implications for gigahertz or terahertz signal-generation applications are discussed.

An adaptive two step paradigm for the super-resolution of optical images is developed in this paper. The procedure locally projects image samples onto a family of kernels that are learned from image data. First, an unsupervised feature extraction is performed on local neighborhood information from a training image. These features are then used to cluster the neighborhoods into disjoint sets for which an optimal mapping relating homologous neighborhoods across scales can be learned in a supervised manner. A superresolved image is obtained through the convolution of a low resolution test image with the established family of kernels. Results demonstrate the effectiveness of the approach.

- by Jose Principe
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- Image Processing, Nonlinear Optics, Multidisciplinary, Optical Imaging
- by Le Binh
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- First-Order Logic, Optical physics, Tunable Filter, First Order Logic

This letter describes a thermally tunable filter of extremely low cost, suitable for optical sensing, spectrometry, and video distribution. The filter utilizes a high-finesse extrinsic fiber Fabry-Pérot interferometer formed by fusion bonding of two mirror-coated single-mode fibers to a short piece of borosilicate tubing. Continuous wavelength tuning is achieved using a Peltier device. We demonstrate a prototype filter operating at 1550 nm with a tuning range of 90.8 nm and a temperature sensitivity of 1.63 nm C. The filter features polarization independence, high repeatability, and inherently low drift and low insertion loss.

- by Gary Pickrell
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- Optical physics, Tunable Filter, Wavelength Division Multiplexing, Fabry Perot

This paper describes a hybrid optical-inertial tracking technology for fully-immersive projective displays. In order to track the operator, the operator wears a 3DOF commercial inertial tracking system coupled with a set of laser diodes arranged in a known configuration. The projection of this laser constellation on the display walls are tracked visually to compute the 6DOF absolute head pose of the user. The absolute pose is combined with the inertial tracker data using an extended Kalman filter to maintain a robust estimate of position and ...

- by Robert S Allison
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- Virtual Reality, Tracking, Optical Filters, Tracking system

offer an attractive solution for indoor applications. To enable terminal mobility and reduce temporal dispersion, we use a configuration known as Multi-Spot-Diffusing (MSD), which is a Multi-Input, Multi-Output (MIMO) architecture. In this configuration, a transmitter generates multiple narrow beams that get uniformly spread over a reflection surface accessible to a service area. A multi-branch receiver with each branch having access to a diffusing spot (generated by transmitter) combines signals on its branches. This scheme creates multiple virtually ideal communications channels between a base station and terminals. This paper considers issues involved in the design of a transmitter-based holographic spot array generator. The generator produces equally-spaced diffusing spots on the room ceiling and/or walls. To overcome power limitation set by eye safety requirements, a receiver optical concentrator is proposed. Furthermore, to improve receiver signal-to-noise ratio, an optical filter that rejects optical noise is needed. Thus, functionally receiver branch optical front-end consists of an optical concentrator and an optical band-pass filter. A single holographic optical element, capable of performing both functions is proposed. Link performance is investigated by providing equivalent link model and comparing probability of error for a bare and a holographic receiver. From performance evaluations, our results show that it is possible to achieve an increase of 11 dB in the SNR and improve power budget by reducing the path loss by over 6 dB. I.

- by Yazan Alqudah
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- MIMO, Holography, Optical Filters, Optical Wireless
- by sohail sheikh
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- Computer Science, Image Processing, Signal Processing, Nonlinear Optics
- by Adam Kunzman
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- Video Processing, Displays, Graphics, System Architecture

We present an optoelectronic oscillator (OEO) that is capable of generating complex and rich dynamics including stable periodic oscillations and broadband chaos. The OEO under analysis here is based on a resonant tunneling diode (RTD) oscillator driving a laser diode and a time-delayed feedback loop. The RTD based OEO is well described as a a Liénard oscillator with delayed-feedback. When subjected to external perturbation, the RTD-OEO generates periodic and chaotic states that are controlled by the delayed-feedback loop characteristics. The implemented numerical Liénard optoelectronic oscillator provides a simple way to study time-delayed dynamical systems containing negative resistance oscillators.

- by kris seunarine
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- Nonlinear Optics, Nonlinear dynamics, Oscillations, Mathematical Model

A signal-processing algorithm has been developed where a filter function is extracted from degraded data through mathematical operations. The filter function can then be used to restore much of the degraded content of the data through use of a deconvolution algorithm. This process can be performed without prior knowledge of the detection system, a technique known as blind deconvolution. The extraction process, designated self-deconvolving data reconstruction algorithm, has been used successfully to restore digitized photographs, digitized acoustic waveforms, and other forms of data. The process is noniterative, computationally efficient, and requires little user input. Implementation is straightforward, allowing inclusion into many types of signal-processing software and hardware. The novelty of the invention is the application of a power law and smoothing function to the degraded data in frequency space. Two methods for determining the value of the power law are discussed. The first method assumes the power law is frequency dependent. The function derived comparing the frequency spectrum of the degraded data with the spectrum of a signal with the desired frequency response. The second method assumes this function is a constant of frequency. This approach requires little knowledge of the original data or the degradation.

This paper presents a new low-noise high-accuracy laser range finder based on the Time-Of-Flight (TOF) method. A Q-switched Nd:YAG laser at 1064 nm as a source and a SLIK avalanche photodiode as a detector are used. The optical section of the system including ZnS/MgF 2 optical filter, designed by C ++ and Zemax software, has been successfully implemented and tested. The quality factor of the optical filter is obtained about 2.53. Using the 1.5 MW Nd:YAG laser, the lowest detectable optical power is limited to about 8.14 nW. The absolute range finding error in the range of 0.3-20 km is also measured as r = ± 50 cm. Furthermore, the sampling rate of the distance measurement can be adjusted between 1 and 20 samples per second.

- by Saeed Olyaee
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- Multidisciplinary, Quality Factor, Time of Flight, Optical Filters

In this work, we focus our interest on blind source camera identification problem by extending our results in the direction of M. Kharrazi et al. (2004). The interpolation in the color surface of an image due to the use of a color filter array (CFA) forms the basis of the paper. We propose to identify the source camera of an image based on traces of the proprietary interpolation algorithm deployed by a digital camera. For this purpose, a set of image characteristics are defined and then used in conjunction with a support vector machine based multi-class classifier to determine the originating digital camera. We also provide initial results on identifying source among two and three digital cameras.

We present a theoretical model developed for estimating the power, the optical signal to noise ratio and the number of generated carriers in a comb generator, having as a reference the minimum optical signal do noise ratio at the receiver input, for a given fiber link. Based on the recirculating frequency shifting technique, the generator relies on the use of coherent and orthogonal multi-carriers (Coherent WDM) that makes use of a single laser source (seed) for feeding high capacity (above 100 Gb/s) systems. The theoretical model has been validated by an experimental demonstration, where 23 comb lines with an optical signal to noise ratio ranging from 25 to 33 dB, in a spectral window of ~ 3.5 nm, are obtained.

- by Daniel Pataca
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- Irrigation, Orthogonal Frequency Division Multiplexing (OFDM), OFDM, Generators

This paper presents a Kalman filter (KF)-integrated optical flow method to measure the velocity of mobile robots using a downward-looking camera. Tests conducted earlier by the authors have shown that currently available differential optical flow methods (X. Song, L. D. Seneviratne, K. Althoefer, and Z. Song, "Vision-based velocity estimation for unmanned ground vehicles," Int. J. Inf. Acquis., vol. 4, no. 4, pp. 303-315, 2007) require large image overlap for accurate velocity estimation. This constraint significantly limits the usefulness of this approach in practical applications. To overcome the problem of dealing with large image displacements, a KF is incorporated to efficiently predict the image transformations. Reducing the feature search area, the KF enables the differential optical flow method to rapidly converge and give accurate velocity estimates. The proposed method has been validated on a linear test rig under laboratory conditions and on a mobile platform in an outdoor field. Test results show good performance of the proposed method in velocity measurements with large image displacements. With this improvement, the required image overlap for feature tracking can be reduced approximately from 80% to 20%, resulting in a fourfold increase of the maximum measurable velocity of the mobile platform. The proposed method has good potential in velocity sensing for mobile robots, particularly in cases, where GPS and inertial measurement unit fail or are unavailable.

- by Lakmal D. Seneviratne
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- Mechanical Engineering, Robot Vision, Integrated Optics, Kalman Filter
- by Bob D Guenther
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- Engineering, Physics, Education, Microscopy

We propose three types of narrowband optical filters based on a Fox-Smith resonator. We demonstrate that by choosing the appropriate combination of coating materials on each prism facet, one can design either a high reflectance or a high transmittance optical filter, suitable for low bit rate optical communication applications with International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) standards. We also show the possibility of designing an optical filter having a desirable finite reflectance/transmittance ratio with simultaneous peaks at ITU-T standard wavelengths. Such filters could be suitable for wavelength tuning applications.

- by M. Moravvej-Farshi and +2
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- Mechanical Engineering, Optical Communication, Optical Communications, Applied Optics

Reference optical configuration for coexistence of 10-Gigabit-capable passive optical networks (XG-PON) with Gigabit passive optical networks (GPON) according to ITU-T G.987.1 standard recommends the usage of specific wavelength blocking filters (WBF). In this contribution, WBFs are designed to separate wavelength bands allocated for XG-PON downstream and upstream signals. The WBFs are proposed to guarantee high filter contrast factors achieved by steep transmission curves in the vicinity of cut-on/cut-off wavelengths of the specific allocated wavelength bands and facilitate migration from legacy GPON to XG-PON. Their deployment protects the allocated wavelength bands from the undesirable interference of GPON with XG-PONs. Wavelength blocking for future wavelength-division-multiplexed PONs is discussed too.

- by Milan Dado
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- Thin Film, Passive Optical Networks, Filter, Wavelength Division Multiplexing

The calibration of a three-dimensional digitizer is a very important issue to take into consideration that good quality, reliability, accuracy and high repeatability are the features which a good digitizer is expected to have. The aim of this paper is to propose a new method for the calibration of a 3-D laser scanner, mainly for robotic applications. The acquisition system consists of a laser emitter and a webcam with fixed relative positions. In addition, a cylindrical lens is provided with the laser housing so that it is capable to project a plane light. An optical filter was also used in order to segment the laser stripe from the rest of the scene. For the calibration procedure it was used a digital micrometer that move a target with known dimensions. The calibration method is based on the modeling of the geometrical relationship between the 3-D coordinates of the laser stripe on the target and its digital coordinates in the image plane. By this method it is possible to calibrate the intrinsic parameters of the video system, the position of the image plane and the laser plane in a given frame, all in the same time.

- by Sergio Savino
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- Engineering, Laser scanner, Three Dimensional, Optical Filters

AI: 1 wt.%) and fibre 3 (A1:3 wt.%).

- by JOhn Canning
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- Ultraviolet, Optical fiber, Glass Fiber, Optical Fibre

A fiber Brag grating sensor interrogator has been developed which is capable of gathering vectors of information from individual fiber Bragg gratings by capturing the full optical spectrum 3 kHz. Using a field programmable gate array with high speed digital-to-analog converters and analog-to-digital components, plus a kilohertz rate MEMS optical filter, the optical spectrum can be scanned at rates in excess of 10 million nanometers per second, allowing sensor sampling rates of many kilohertz while maintaining the necessary resolution to understand sensor changes. The autonomous system design performs all necessary detection and processing of multiple sensors and allows spectral measurements to be exported as fast as Ethernet, USB, or RS232 devices can receive it through a memory mapped interface. The high speed - full spectrum - fiber Bragg grating sensor interrogator enables advanced interrogation of dynamic strain and temperature gradients along the length of a sensor, as well as the use of each sensor for multiple stimuli, such as in temperature compensation. Two examples are described, showing interrogation of rapid laser heating in an optical fiber, as well as complex strain effects in a beam that had an engineered defect.

- by Zixu Zhu
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- Field-Programmable Gate Arrays, Microelectromechanical systems, Proceedings, Sensors

Removing the motion artifacts from measured photoplethysmography (PPG) signals is one of the important issues to be tackled for the accurate measurement of arterial oxygen saturation during movement. In this paper, the motion artifacts were reduced by exploiting the quasi-periodicity of the PPG signal and the independence between the PPG and the motion artifact signals. The combination of independent component analysis and block interleaving with low-pass filtering can reduce the motion artifacts under the condition of general dual-wavelength measurement. Experiments with synthetic and real data were performed to demonstrate the efficacy of the proposed algorithm.

- by Ashoka Reddy
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- Algorithms, Biomedical Engineering, Biomechanics, Independent Component Analysis

The light originating from seven light-emitting diodes of different colours is guided, one at a time, into a measuring cell by means of a fibre optic coupler. Detection is carried out with photodiodes which are connected to a log-ratio amplifier yielding direct absorbance readings. Optical filters are used to narrow the emission band from blue light emitting diodes as these bands are relatively wide compared to those of the emitters of other colours. An inexpensive and compact multi-wavelength photometer covering the visible range is thus obtained, which in many cases can replace a conventional spectrophotometer for absorbance measurements. The performance for a range of commonly used photometric analytical procedures is described and compared to conventional measurements with a spectrophotometer.

- by Thusitha Rupasinghe
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- Analytical Chemistry, Blue Light, Optical Filters, Light Emitting Diode

Ozetçe Holografi gerçeküç boyutlu (3B) görüntüleme imkânı saglamaktadır fakat kaydetme ve yeniden yapılandırma sırasında kaçınılmaz olarak ortaya çıkan sıfır derece imgesi ve eşlenik imge sanal nesne imgesinin kalitesini düşürmektedir. Bu makale hologram kaydetme ve yeniden yapılandırma sürecinin anlatılımı ile başlamaktadır. Holografide filtreleme kavramının açıklanmasının ardından hali hazırda bulunan filtreleme yöntemleriözetlenmiş ve gerçekleme sonuçlarıyla desteklenmiştir. Daha sonra Hilbert dönüşümü tabanlı yeni bir filtreleme yöntemiönerilmiştir.Önerilen filtreleme yönteminin performansı Ortalama Kare Hatası (OKH) ile degelendirilmiş ve sinyal gürültü oranında kayda deger bir gelişme gözlenmiştir.

- by Muharrem Bayraktar
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- Nonlinear Optics, Image Reconstruction, Holography, Mean square error

Large cylindrical [001] direction α-nickel sulphate hexahydrate crystal with 20 mm diameter and 140 mm length was grown from an aqueous solution by uniaxially solution-crystallization method of Sankaranarayanan-Ramasamy (SR). The grown... more

at which the fusion is accomplished; the objectives of the fusion process, the application domain; the types of sensors employed, the sensor suite configuration and so on. The characterization most commonly encountered in the rapidly growing sensor fusion literature based on level of detail in the information is that of the now well known triplet: data level, feature level, and decision level. We consider here a generalized input-output (I/O) descriptor pair based characterization of the sensor fusion process that can be looked upon as a natural out growth of the trilevel characterization. The fusion system design philosophy expounded here is that an exhaustive exploitation of the sensor fusion potential should explore fusion under all of the different I/O-based fusion modes conceivable under such a characterization. Fusion system architectures designed to permit such exploitation offer the requisite flexibility for developing the most effective fusion system designs for a given application. A second facet of this exploitation is aimed at exploring the new concept of self-improving multisensor fusion system architectures, wherein the central (fusion system) and local (individual sensor subsystems) decision makers mutually enhance the other's performance by providing reinforced learning. A third facet is that of investigating fusion system architectures for environments wherein the different local decision makers may only be capable of narrower decisions that span only a subset of decision choices. The paper discusses these flexible fusion system architectures along with related issues and illustrates them with examples of their application to real-world scenarios.

We demonstrate a compact tunable chirp managed laser (CML) comprising a radio-frequency switch, a directly modulated distributed feedback laser array, a microelectromechanical systems mirror, and an optical filter and obtain error-free transmission performance over 30 nm at 10.7 Gb/s up to 200 km without electrical dispersion compensation (EDC) or optical dispersion compensation. Transmission distance is stretched to 300 km over the same wavelength range by adding a standard EDC to the receiver.

- by Raghuram Narayan
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- Photonics, Radio Frequency, Dispersion Compensation, Optical physics

This paper presents recent results in the development of novel ultrafast technologies based on the generation and application of stabilized optical frequency combs. By using novel active resonant cavity injection locking techniques, filtering, modulation and detection can be performed directly on individual components of the frequency comb enabling new approaches to optical waveform synthesis, waveform detection and matched filtering, with effective signal processing bandwidths in excess of 1 THz.

- by Peter Delfyett
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- Quantum Physics, Signal Processing, Ultrafast Optics, Matched Filter

The generation of flat top pulse with 10 ps duration at 266 nm, is of extreme importance to achieve low emittance electron beam from a photoinjector. The production of this pulse shape is carried out using manipulation in the frequency domain with the aid of new programmable pulse shapers. In this paper we present the experimental measurements we performed to characterize two pulse shapers: the acousto-optics filter, namely the DAZZLER, and the liquid crystal mask spatial light modulator. The measurement have been performed with the amplified Ti:Sa laser system used to drive the SPARC photoinjector at LNF-INFN. The results obtained, the operation and the main limitations of the two techniques are also presented.

- by C. Vicario
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- Comparative Study, Spatial Light Modulator, Pulse Shaping, Liquid Crystal

Standard Reference Materials® SRMs 2241 through 2243 are certified spectroscopic standards intended for the correction of the relative intensity of Raman spectra obtained with instruments employing laser excitation wavelengths of 785 nm, 532 nm, or 488 nm/514.5 nm. These SRMs each consist of an optical glass that emits a broadband luminescence spectrum when illuminated with the Raman excitation laser. The shape of the luminescence spectrum is described by a polynomial expression that relates the relative spectral intensity to the Raman shift with units in wavenumber (cm−1). This polynomial, together with a measurement of the luminescence spectrum of the standard, can be used to determine the spectral intensity-response correction, which is unique to each Raman system. The resulting instrument intensity-response correction may then be used to obtain Raman spectra that are corrected for a number of, but not all, instrument-dependent artifacts. Peak area ratios of the intensity-correct...

- by Steven Choquette
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- Mechanical Engineering, Optics, Analytical Chemistry, Medical Imaging

In-band crosstalk due to Rayleigh backscattering (RB) can be avoided in bidirectional wavelength-division multiplexed (WDM) transmission systems when using two identical sets of wavelengths in opposite directions over a single fiber. We describe this by using such sets in a disjoint manner and eliminating the RB crosstalk with the help of simple optical edge filters instead of the WDM comb filters previously employed in interleaved bidirectional systems. We also provide a practical application example and describe the power penalty due to the interferometric RB crosstalk, taking into account recent polarized optical noise research because RB light is partially polarized. Numerical results for externally modulated intensitymodulation/direct-detection (IM/DD) optical systems show that the power penalty can be kept less than 0.5 dB with moderate edge filters, even for more than several tens of optically amplified repeater segments.

- by Hitoshi Obara
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- Optics, Medical Imaging, Fiber Optics, Telecommunications

The advances in optoelectronics over the last three decades have been quite dramatic, namely the mass manufacturing of low cost integrated circuits, revolutionizing the speed and the capability of computing and communication. However, today's ever-increasing demand for high-bandwidth data is outgrowing the performance of electronics in many applications, such as in telecommunications where the traffic demand has been increasing steadily and, therefore, the transmission technology requires bandwidth that exceeds the one provided by actual copper based networks. In this context, the fabrication of lowcost integrated optics (IO) devices using sol-gel derived organic-inorganic hybrid (OIH) materials has received increasing attention in the last years. This review will focus on examples of OIHs that can be used in IO devices for the next generation of optical networks. Emphasis will be given to passive (planar and channel waveguides, couplers and multimode interference splitters) and active (lasers and optical amplifiers) optical architectures for long haul/metro and access/indoor networks.

- by Paulo Andre
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- Optical network, Planar Waveguide, Optical Filters, Beam Propagation Method

We experimentally demonstrate the feasibility of the bandwidth tuning of a liquid-crystal based bandpass Lyot filter. This bandwidth tuning is achieved by applying a voltage to vary the birefringence of the liquid-crystal cells whose optical path difference takes predefined discrete values. We show that for a 2-stage liquid-crystal Lyot filter and at λ i = 1.543 μm, the measured 3-dB bandwidth varies from 17nm to 60 nm when the applied voltage increases from 0V to 5.24V. The shape of the transmission response remains unchanged during the bandwidth tuning process.

- by Rachid Hamdi and +2
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- Optical Communication, Optical fiber, Liquid Crystal, Band Pass Filter

High-contrast optical filtering is demonstrated using cascaded silicon microrings. We report an experimental measurement of a record 100 dB pass-band to stop-band contrast, tunable 12-125 GHz passband full-width at half-maximum, band-center insertion loss ripple <3 dB, and a group delay ripple <5 ps, using transverse electric polarized light.

Bachelor´s thesis for Helsinki University (in finnish). An attempt at documenting neolithic rock paintings using alternative wavelengths. Theoretical discussion about using hyperspectral cameras in archaeology in general. Experiment in modifying a DSLR by removing the internal filter and some basic image enhancement to bring out the painting.
Also reporting a rubbing of two letters at the Vitträsk painting in Kirkkonummi, Finland, visible in the included images.

- by Perttu Strandman
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- Archaeology, Rock Art (Archaeology), Hyperspectral Imaging, Bachelor Thesis

This article addresses the development of and recent advances in the rapidly growing jield of optical pattem recognition. In optical pattern recognition there are two basic approaches; namely, matched filtering and associative memories. The first employs optical correlator architectures and the latter uses optical neural networks (NN's). This paper reviews various types of optical correlators and NN's applied to real-time pattern recognition and autonomous tracking. Techniques of scale and rotational invariant jiltering are also given. Recent approaches using wavelet transfom filtering, phase only jiltering, high capacity composite filters, and phase representation f o r improvement in pattern discrimination are also provided.

- by Don Gregory
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- Biomedical Engineering, Pattern Recognition, Neural Networks, Neural Network

This paper presents an approach to designing narrowband digital filters that are realizable using optical allpass building blocks. We describe a top-down design method by explicitly examining the derivation of an Infinite Impulse Response (IIR) architecture. Our result demonstrates a design that can achieve a 0.0025π passband edge while providing 60dB stopband attenuation. The design is aimed to reduce filter pole magnitudes, providing tolerance for waveguide losses and fabrication errors. The narrowband filter is based on the foundation of latticed allpass sections, which makes it naturally realizable using basic photonic components. Furthermore, analysis is performed on delay length variations that can result from the fabrication process.

- by truong nguyen
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- Mathematics, Computer Science, Photonics, Adaptive Optics

Wideband Ti : LiNbO 3 optical modulators for 40 Gb/s applications, Proc. ECOC'98, Madrid, Spain, 1998, pp. 547-548. 24. S. Yamada and M. Minakata, DC drift Phenomenon in LiNbO 3 optical waveguide devices, Jpn. J. Appl. Phys. 20: 733-737 (1981). 25. M. Seino, T. Nakazawa, M. Doi, and S. Taniguchi, The long term reliability estimation of Ti : LiNbO 3 modulator for DC drift, Proc. IOOC'95, Hong Kong, paper PD1-8, 1995, pp. 15-16. 26. I. Sawaki, H. Nakajima, M. Seino, and K. Asama, Thermally stabilized z-cut Ti : LiNbO 3 waveguide switch, Proc.

- by Alexandros Stavdas
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- Wdm, Diffraction Gratings, Optical Filters, Multiplexers

Gesture recognition pertains to recognizing meaningful expressions of motion by a human, involving the hands, arms, face, head, and/or body. It is of utmost importance in designing an intelligent and efficient human-computer interface. The applications of gesture recognition are manifold, ranging from sign language through medical rehabilitation to virtual reality. In this paper, we provide a survey on gesture recognition with particular emphasis on hand gestures and facial expressions. Applications involving hidden Markov models, particle filtering and condensation, finite-state machines, optical flow, skin color, and connectionist models are discussed in detail. Existing challenges and future research possibilities are also highlighted.

- by Tinku Acharya
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- Engineering, Human Computer Interaction, Computer Vision, Image Processing

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- by Rod Waterhouse
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- Spine, Amplified spontaneous emission, Optical Fibre, Superradiance

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Optical microcavities trap light in compact volumes by the mechanisms of almost total internal reflection or distributed Bragg reflection, enable light amplification, and select out specific (resonant) frequencies of light that can be emitted or coupled into optical guides, and lower the thresholds of lasing. Such resonators have radii from 1 to 100 µm and can be fabricated in a wide range of materials. Devices based on optical resonators are essential for cavityquantum-electro-dynamic experiments, frequency stabilization, optical filtering and switching, light generation, biosensing, and nonlinear optics.

- by Ana Vukovic
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- Nonlinear Optics, Integrated Optics, Photonic Crystal, Spontaneous Emission

The historical beginnings of photosensitivity and fiber Bragg grating (FBG) technology are recounted. The basic techniques for fiber grating fabrication, their characteristics, and the fundamental properties of fiber gratings are described. The many applications of fiber grating technology are tabulated, and some selected applications are briefly described.

- by mohamad Hashemi
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- Fiber Bragg grating, Optical fiber sensor, Photosensitivity, Optical physics

A method for evaluating the average error probability in digital fiber optic transmission systems is described. It takes into accouat the statistical properties of the main impairments that affect the information siguaf, i.e., shot noise (dark current included), thermal noise, aad intersymbol interference. Unlike other methods, the analysis of shot-noise statfstica does not entail the second-moment characterization alone, but uses a number of moments sufficient to evaluate the error probability with a biglt degree of accuracy. For this pmpose it is shown how the cumulauts of shot noise. and intersymbol interference of any order can be computed. The baseband pulse response and the statistical distribution of the avalanche-photodetector gain are assumed to be available. Moreover, tecbniquea for exploiting the cumulants are given; knowledge of the cumulants allows one to compute the probability of error by means of Gaussian numerical integration rules. Finally, some results and comparisuns are reported.

- by Angelo G Luvison and +1
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- Probability Theory, Fiber Optics, Statistical Analysis, Digital Systems

In this paper, we experimentally demonstrate a single-band self-coherent polarization-multiplexed optical orthogonal frequency-division multiplex system with a raw data rate of 120 Gbit/s. The transmitter uses a novel RF structure that eliminates the need for RF mixers and optical filters. The receiver uses a novel architecture where the optical carrier is filtered and amplified for self-coherent detection. The receiver is polarization diverse and allows for the usual frequency guard band between the carrier and the sideband to be reduced in width, thus increasing spectral efficiency. Using two commercial 20 GS/s arbitrary-waveform generators to generate a single information-carrying band per polarization, we achieve a raw data rate of 120 Gbit/s over 500 km of standard single-mode fiber.

- by Zuraidah Zan
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- Optical physics, Single Mode Fiber, Spectral Efficiency, Optical Filters

In this paper, a unified theory for the newly developed optical burst-mode receiver is presented. Based on this theory, an analysis of the performance of the receiver is given both theoretically and experimentally. The theoretical model agrees well with the experimental results. This theory can quantitatively explain the bit error rate (BER) performance of burst-mode receivers. Several potential applications of burst-mode receivers are also illustrated, including applications in supervisory system for erbium-doped fiber amplifier (EDFA) trans-oceanic optical links and various high-speed all-optical multiaccess packet networks.

- by Lian Kuan Chen
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- Packet Switching, Erbium Doped Fiber Amplifier, Bit Error Rate, Optical physics

We demonstrate photonic circuits monolithically integrated on an InP-based platform for use in coherent communication links. We describe a technology platform that allows for the integration of numerous circuit elements. We show examples of an integrated transmitter which offers an on-chip wavelengthdivision-multiplexing source with a flat gain profile across a 2 THz band and a new device design to provide a flatted gain over a 5 THz band. We show coherent receivers incorporating an integrated widely tunable local oscillator as well as an optical PLL. Finally, we demonstrate a tunable optical bandpass filter for use in analog coherent radio frequency links with a measured spurious-free dynamic range of 86.3 dB-Hz 2/3 as well as an improved design to exceed 117 dB-Hz 2/3 .

- by Pietro Binetti
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- Integrated Optics, IEEE, Optical Waveguide, Radio Frequency

Microring and microdisk resonators are used in photonic circuits to perform filter functions, serve as bandlimited mirrors in lasers, compensate for dispersion and group delay distortion, are used in multiplexers in telecommunication systems, and a number of other applications such as medical instrumentation, biosensing, interferometry, to name a few. This paper outlines some challenges and solutions in this relatively new and prolific discipline.

- by Otto Schwelb
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- Seismic analysis and design, Delays, Optical Filters, Ring Resonator