A scheme of developing frequency encoded tristate-optical logic operations using semiconductor optical amplifier

The ever increasing demand for very fast and agile optical networks requires very fast execution of different optical and logical operations as well as large information handling capacities at the same time. In conventional binary logic based operations the information is represented by two distinct states only (0 and 1 state). It limits the large information handling capacity and speed of different arithmetic and optical logic operations. Tristate based logic operations can be accommodated with optics successfully in data processing, as this type of operation can enhance the speed of operation as well as increase the information handling capacity. Here in this communication the author proposes a new method to implement all-optical different logic gates with tristate logic using the frequency-encoding principle. The frequency encoding/decoding based optical communication has distinctly great advantages because the frequency is the fundamental character of an optical signal and it preserves its identity throughout the communication. The principle of the rotation of the state of polarization of a probe beam through semiconductor optical amplifier (SOA), frequency routing property of an optical add/drop multiplexer (AD) and high frequency conversion property of reflecting semiconductor optical amplifiers (RSOA) have been exploited here to implement the desired AND, OR, NAND and NOR logic operations with tristate logic.     

Three-dimensional shape measurement using improved binary spatio-temporal encoded illumination and voting algorithm

Some regions of objects will be measured incorrectly or cannot be measured in optical three-dimensional (3D) measurement system based on coded structured light, due to occlusion, shadow, transfer function of measurement system, and noise. To obtain 3D data as much as possible and as correctly as possible, we proposed a method using improved binary spatio-temporal encoded illumination and voting algorithm. Firstly, the binary spatio-temporal encoded (BSE) pattern is improved with a redundancy encoding method. One code is assigned to two adjacent sections and distinguished with their temporal coordinates. The redundancy encoding method provides more cues for code correcting and retrieving. Secondly, symbols are estimated according to four coding cues--code redundancy, continuity of stripes, intensity variation in temporal direction, and neighbor symbols in sequence. Finally, a voting algorithm is adopted to obtain final symbols. A plaster model of a human head was measured to validate the method. The experimental results reveal that more valid points can be obtained and the reliability of the decoding results is improved.     

Optical encryption system with a binary key code

A double-random-phase optical encryption system that uses a binary key code is proposed. The key code is generated as a binary computer-generated hologram. The binary key code can be displayed on a binary spatial light modulator (SLM) such as a ferroelectric liquid-crystal display. The use of a binary SLM enables us to renew the key at high speed. A joint transform correlator based on a photorefractive crystal in the Fourier domain is used to perform shift-invariant encryption and decryption. Computer simulations of the effects of using a binary encoded key code instead of a complex amplitude key code are shown. Preliminary optical experimental results are presented to demonstrate the effectiveness of the proposed system.     

All-optical quaternary logic gates

Conventional binary logic based operations restrict the speed of operations as well as information handling capacity. A way to overcome these limitations is the implementation of multivalued logic operations in the optical domain. Multivalued logic operations not only enhance the data handling capacities but also increase the speed of processing. integrating enormous potential bandwidth of optical fiber as information carrying medium and faster optoelectronic/optical switches with no hardware complexity. A new method is proposed for the implementation of all-optical quaternary inversion, MAX, MIN, and equality operations using frequency-encoded data. Cross phase modulation-based frequency conversion, polarization switch (PSW) characteristics of a semiconductor optical amplifier (SOA), frequency routing by a wave division multiplexer (MUX), and a demultiplexer (DMUX) have been exploited to implement the desired quaternary logic operations. Simulation results support the feasibility of the proposed scheme.     

Reconsidering natural binary encoding for absolute positionmeasurement application

It is well known that absolute encoders using natural binary codes are prone to reading errors because more bits can change between adjacent scale sectors. Some solutions, such as V-scan, were proposed to solve this problem, but they required too many additional reading heads and decoding circuits to be competitive with the reduced complexity obtained when using the Gray code. The author describes a novel natural binary absolute encoder using an original scanning technique that solves more efficiently the problem of the inherent code reading errors. It is shown that for the same nominal resolution, the complexity of the encoder is similar to, if not better than, that of the Gray-type encoder     

基于量子比特平面编码算法的图像重建研究

为了提高图像重建质量,提出量子比特平面编码算法。首先进行图像像素灰度段编码,获得中间段灰度级滤波矩阵;然后量子比特经过Walsh-Hadamard变换,将输入图像像素分解出低频部分和高频部分;接着分别对正系数矩阵和负系数矩阵扫描,在正负系数比特平面码流之间插入一个比特标志;最后给出了图像重建过程。实验仿真显示本文算法的重建效果清晰,指标分析图像信噪比最大,均方根误差较接近于0。     

10 Gbit/s optical wavelength converter with a Brillouin scattering-based spectral filter

For the first time, to our knowledge, a highly robust, high-bit-rate (10 Gbit/s) wavelength converter that is based on a narrow Brillouin filter is reported. The conversion takes place in a semiconductor optical amplifier (SOA) in a cross-gain-phase process. The SOA operates in a weak-modulation mode, and the exiting signal undergoes a dc reduction with a narrow spectral filter. In our system we perform spectrally narrow filtering by using a long Brillouin grating.     

灰色接近关联度在香料指纹图谱模式识别中的应用

灰色关联分析是灰色系统理论中十分活跃的一个分支,其基本思想是根据序列曲线的几何形状的相似程度来判断其联系是否紧密。曲线越接近,相应序列之间的关联度就越大,反之就越小。文章系统地介绍灰色接近关联度基本理论和两种面积的算法,详细地说明灰色接近关联度的计算方法及使用范围以及在色谱指纹图谱中的应用,包括仪器使用方法及具体计算过程。     

All optical format conversion at 10 Gbps using SOA and optical band-pass filter

In this paper, an all-optical non return-to-zero (NRZ) and return-to-zero (RZ) modulation format converter using a single semiconductor optical amplifier (SOA) and an optical band-pass filter (OBPF) is proposed. The format converter consists of a single SOA which is acting as a nonlinear element to broaden the spectrum of the input signal and the OBPF which is used to extract the special spectrum from the broadened spectrum. By adopting the ultra-fast SOA model associated with optical system software, the 10 Gbps NRZ and RZ format conversion is successfully demonstrated with simulation. We also demonstrate the proof-of-principle experiment at 10 Gbps by using the test SOA and OBF converter. The converted NRZ is achieved with an output extinction ratio of 11.51 dB. The BER is 5.5 × 10^?9 while the power of NRZ is ?10 dBm and the BER is 1.0 × 10^?9 when the power of RZ is ?14 dBm. The experimental results coincide well with the simulated results. The proposed scheme is robust and has potential for applications in future optical networks.     

Effects of binary encoding on pattern recognition and library matching of spectral data

Scott, D.R., 1988. Effects of binary encoding on pattern recognition and library matching of spectral data. Chemometrics and Intelligent Laboratory Systems, 4: 47–63.Binary encoding is frequently employed in pattern recognition studies and matching of unknown against library spectral data. In this study the effect of binary encoding on pattern recognition and library searches is determined using the Hamming and Euclidean distance metrics. The effect on a full intensity spectrum is to compress the total information into a qualitative spectral data vector, the most basic information in the full spectrum. Geometrically, binary encoding of unit normalized spectral data can be visualized as shifting spectral points on the faces of the measurement space hypercube to the corners of a Hamming hypercube. A new classification scheme for comparison of analytical spectra based on their binary encoded spectra is introduced. Quantitative expressions for the effect of binary encoding on general Euclidean distances between spectral points are derived and shown to depend upon their spectral classification. Generally binary encoding increases the interclass distances in pattern recognition and may decrease the intraclass distances. This effect is illustrated with a mass spectral pattern recognition example. The effect of binary encoding on library searches is to produce possible false compound identification in identity searches and to flag spectrally similar compounds in structure searches. A scheme which uses both the Hamming and the Euclidean metrics is proposed for improved library searches. This scheme is illustrated with searches of a small mass spectral library for benzene and p-dioxane spectra.     

Robust Intermediate Read-Out for Deep Submicron Technology CMOS Image Sensors

In this paper, a CMOS image sensor featuring a novel spiking pixel design and a robust digital intermediate read-out is proposed for deep submicron CMOS technologies. The proposed read-out scheme exhibits a relative insensitivity to the ongoing aggressive scaling of the supply voltage. It is based on a novel compact spiking pixel circuit, which combines digitizing and memory functions. Illumination is encoded into a Gray code using a very simple yet robust Gray 8-bit counter memory. Circuit simulations and experiments demonstrate the successful operation of a 64 64 image sensor, implemented in a 0.35 CMOS technology. A scalability analysis is presented. It suggests that deep sub-0.18 will enable the full potential of the proposed Gray encoding spiking pixel. Potential applications include multiresolution imaging and motion detection.     

Full-complex amplitude modulation with binary spatial light modulators

Imperfections and nonrobust behavior of practical multilevel spatial light modulators (SLMs) degrade the performance of many proposed full-complex amplitude modulation schemes. We consider the use of more robust binary SLMs for this purpose. We propose a generic method, by which, out of K binary (or 1 bit) SLMs of size M×N, we effectively create a new 2(K)-level (or K bit) SLM of size M×N. The method is a generalization of the well-known concepts of bit plane representation and decomposition for ordinary gray scale digital images and relies on forming a properly weighted superposition of binary SLMs. When K is sufficiently large, the effective SLM can be regarded as a full-complex one. Our method is as efficient as possible from an information theoretical perspective. A 4f system is discussed as a possible optical implementation. This 4f system also provides a means for eliminating the undesirable higher diffraction orders. The components of the 4f system can easily be customized for different production technologies.     

Two-dimensional position recovery for a free-ranging automatedguided vehicle

An absolute position recovery method for an automated guided vehicle (AGV) which can move in any direction (free-ranging) on the floor using vision is introduced. The floor is permanently encoded with the terms of a pseudorandom binary array requiring only one bit of code per quantization interval, independent of the desired resolution     

Channel capacity model of binary encoded structured light-stripe illumination

A common approach to structured light-illumination measurement is to encode a surface topology successively with binary light-stripe patterns of variable spatial frequency. Each surface location is thereby encoded with a binary sequence associated with its height. By analyzing the lateral displacements of the reflected encoded pattern, one can reconstruct the surface topology without ambiguity. We present a model for multistripe analysis in terms of an information channel for which the maximum spatial stripe frequency is related to channel capacity and maximized accordingly by use of Shannon's theorems. The objective is to improve lateral resolution through optimized spatial frequency while maintaining a fixed range resolution. Given an optimized spatial frequency, a technique is presented to enhance lateral resolution further by multiplexing the light structure. Theoretical and numerical results are compared with experimental data.     

A novel optical device with wide-bandwidth wavelength conversionand an optical sampling experiment at 200 Gbit/s

This paper reports the characteristics of our proposed prototype optical parametric diffuser (OPD). An OPD is based on the theory of four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). However, to improve the conversion bandwidth and FWM efficiency, the gain bandwidth is spread and the gain peak wavelengths are set to a wavelength near the FWM light on the short-wavelength side by combining different MQW active layers. We measured the optical gain characteristics; the fiber-to fiber gain was 16.1 dB and the gain bandwidth over 8 dB was 117 nm when driven at 200 mA dc, and 190 nm when driven by an 800 mA pulse current. In a wavelength-conversion experiment, a high conversion efficiency of ⩾-20 dB was obtained across a detuning wavelength bandwidth of 43 nm. A clear waveform was obtained in an optical sampling experiment to measure 200 Gbit/s optical data sequences     

Four-Channel, 8 x 8 Bit, Two-Dimensional Parallel Transmission by use of Space-Code-Division Multiple-Access Encoder and Decoder Modules

We experimentally demonstrate four-channel multiplexing of 64-bit (8 x 8) two-dimensional (2-D) parallel data links on the basis of optical space-code-division multiple access (CDMA) by using new modules of optical spatial encoders and a decoder with a new high-contrast 9-m-long image fiber with 3 x 10(4) cores. Each 8 x 8 bit plane (64-bit parallel data) is optically encoded with an 8 x 8, 2-D optical orthogonal signature pattern. The encoded bit planes are spatially multiplexed and transmitted through an image fiber. A receiver can recover the intended input bit plane by means of an optical decoding process. This result should encourage the application of optical space-CDMA to future high-throughput 2-D parallel data links connecting massively parallel processors.     

Fiber-optic localization by geometric space coding with a two-dimensional gray code

With the objective of monitoring motion within a room, we segment the two-dimensional (2D) floor space into discrete cells and encode each cell with a binary code word generated by a fiber. We design a set of k-neighbor-local codes to localize an extended object and, particularly when k = 2, employ a 2D gray code to localize a human by tracking his or her footsteps. Methods for implementing the codes in a fiber web are discussed, and we demonstrate the experimental result with the fiber mat. The observed system performance confirms the theoretical analysis. The space coding technique is a promising low-cost candidate not only for human tracking but also for other applications such as human gait analysis.     

All-optical method for the addition of binary data by nonlinear materials

An all-optical system for the addition of binary numbers is proposed in which input binary digits are encoded by appropriate cells in two different planes and output binary digits are expressed as the presence (=1) or the absence (=0) of a light signal. The intensity-based optical XOR and AND logic operations are used here as basic building blocks. Nonlinear materials, appropriate cells (pixels), and other conventional optics are utilized in this system.     

O-band to C-band wavelength converter by using four-wave mixing effect in 1310 nm SOA

In this paper we provide a detailed account of an ultra-wideband wavelength converter that shifts from 1310 to 1550?nm using a 1310?nm semiconductor optical amplifier as the nonlinear medium. The experimental approach uses an arrayed waveguide grating (AWG) as a method to slice the broadband output ASE of the 1310?nm SOA into multiple outputs at this O-band. A four-wave mixing technique is used to generate the wavelength conversion, whereby two wavelengths at 1310?nm are used and interact with the 1550?nm continuous wave output from a bismuth-based erbium-doped optical amplifier. In this demonstration, the interacting wavelengths are 1316.75, 1317.47 and 1542.21?nm. The downward conversion wavelengths are 1542.93 and 1541.49?nm, with a converted wavelength spacing of 224?nm.     

Absolute, high-resolution optical position encoder

Modern computer-controlled manufacturing machinery requires the absolute and highly accurate measurement of the linear position. Such an absolute, optical linear position encoder is described here. It is based on the transilluminance of a glass scale with an inexpensive light-emitting diode. The scale has two code tracks, one based on a pseudo-random binary sequence for the coarse determination of position and another periodic code for accurate fine-position measurement. A single-lens telecentric optical system images the code tracks in a mechanically insensitive way onto a custom photodetector. This special detector IC is capable of determining the components of the (complex) Fourier transform for the spatial frequency of the periodic code. The absolute optical position encoder shows a resolution of 10 nm and an absolute accuracy of better than 100 nm over short distances, verified with a commercial laser interferometer.