Mach-Zehnder interferometer-based tree architecture for all-optical logic and arithmetic operations

Interferometric devices for optical processing have been of great interest in recent years. Semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometer (MZI) has already taken a significant role in the field of ultra-fast all-optical signal processing. Optical tree architecture (OTA) provides important contributions in optical interconnecting networks. In this communication, we have tried to exploit the advantages of both OTA and SOA-based MZI switches. We have proposed SOA-MZI-based tree architecture, a new and alternative scheme, for integrated all-optical logic and arithmetic operations. This architecture can enable one to perform all-optical processing of signals, including two input logic operations, half-adder, full-adder, full-subtractor, one-bit data comparator, etc.     

All-optical conversion scheme: Binary to quaternary and quaternary to binary number

To achieve the inherent parallelism in optics a suitable number system and efficient encoding/decoding scheme for handling the data are very much essential. Binary number is accepted as the best representing number system in almost all types of existing electronic computers. But, binary number (0 and 1) is insufficient in respect to the demand of the coming generation. Multi-valued logic (with radix >2) can be viewed as an alternative approach to solve many problems in transmission, storage and processing of large amount of information in digital signal processing. Here, in this paper all-optical scheme for the conversion of binary to quaternary number and vice versa have been proposed and described. Simulation has also been done. In this all-optical scheme the numbers are represented by different discrete polarized state of light.     

An all-optical matrix multiplication scheme with non-linear material based switching system

Optics is a potential candidate in information, data, and image processing. In all-optical data and information processing, optics has been used as information carrying signal because of its inherent advantages of parallelism. Several optical methods are proposed in support of the above processing. In many algebraic,arithmetic, and image processing schemes fundamental logic and memory operations are conducted exploring all-optical devices. In this communication we report an all-optical matrix multiplication operation with non-linear material based switching circuit.     

Method of developing all-optical parallel to serial converter exploiting Kerr non-linearity of medium

Different all-optical logic operations, memory blocks etc. are developed using the inherent parallelism of optics. In any digital communication and computation system, the role of serial to parallel and parallel to serial data conversion are very much essential for making a data convenient for transition.Here in this paper, the authors propose a new scheme for developing an all-optical parallel to serial data conversion system by using optical J-K Flip-Flops and some logic gates based on optical non-linear switches. The uses of such switches are widely established in the area of optical parallel computation.This process can be extend for developing some all-optical digital devices like shift register, optical pulse counters etc. The proposed scheme deals with the best use of high parallelism of the optics, so the super-fast processing speed can be achieved.     

An all-optical integrated system for implementing arithmetic operation in 2’s complement method with the active participation of non-linear material based switches

Optics is regarded undoubtedly a potential and successful candidate in information and data processing because of its inherent parallelism. In last few decades several all-optical data processors, algebraic processors, arithmetic processors are proposed. Here in this communication the authors propose a completely new scheme for implementing binary data arithmetic in 2’s Complement method which is the most advantageous among all other established subtraction methods. To implement it we use non-linear material massively.     

Design of ternary Multiplexer and De-multiplexer circuit with optical nonlinear material (OPNLM) based switch

Multiplexer and De-multiplexer operation play a very important role in all-optical computation, communication and control. Considerable number of multiplexing – de-multiplexing scheme in digital optical processing have already been reported. A design of all-optical ternary Multiplexer De-multiplexer circuit with optical nonlinear material (OPNLM) based switch is proposed and described in this paper. Different logic states have been represented by different polarization states of light. Logical simulation is also included here. This circuit will be useful in future all-optical multi-valued logic based computing and information processing system.     

Implementation of an all-optical binary comparator based on material nonlinearity and polarization encoded light signal

Bitwise comparison and classification of binary data is an essential requirement in digital signal and image processing applications. Here in this paper a new method of a one bit all-optical binary comparison scheme is proposed. This scheme is developed by the proper use of optical nonlinear material and also polarization encoding technique. Very high speed performance can be adopted easily in this mechanism. The scheme can be used to compare any two bits such as 0 and 0, 0 and 1, 1 and 0, 1 and 1.     

Terahertz optical asymmetric demultiplexer based tree-net architecture for all-optical conversion scheme from binary to its other 2n radix based form

To exploit the parallelism of optics in data processing,a suitable number system and an efficient encoding/decoding scheme for handling the data are very essential.In the field of optical computing and parallel information processing,several number systems like binary,quaternary,octal,hexadecimal,etc.have been used for different arithmetic and algebraic operations.Here,we have proposed an all-optical conversion scheme from its binary to its other 2n radix based form with the help of terahertz optical asymmetric demultiplexer (TOAD) based tree-net architecture.     

基于TOAD的10Gb/s全光或门

基于太赫兹光非对称解复用器（TOAD），提出了一种全光或门的实现方案.从TOAD原理出发，从理论上证实了该方案实现全光或运算的可行性.在此基础上进行了实验研究，成功实现了10 Gb/s的全光或运算.实验采用1100和0110编码的两路数据信号，完全验证了或运算真值表中各种可能的情况，并显示出该方案对实现任意编码或伪随机码数据或运算的潜力.对SOA增益恢复时间对结果的影响提出了改进办法.最后分析表明,该方案具有实现超高速高消光比或运算的潜力.     

Reconfigurable all-optical dual-directional half-subtractor for high-speed differential phase shift keying signal based on semiconductor optical amplifiers

All-optical digital logic elementary circuits are the building blocks of many important computational operations in future high-speed all-optical networks and computing systems. Multifunctional and reconfigurable logic units are essential in this respect. Employing the demodulation properties of delay interferometers for input differential phase shift keying signals and the gain saturation effect in two parallel semiconductor optical amplifiers, a novel design of 40 Gbit/s reconfigurable all-optical dual-directional half-subtractor is proposed and demonstrated. All output logic results show that the scheme achieves over 11=dB extinction ratio, clear and wide open eye diagram, as well as low polarization dependence (< 1 dB), without using any additional input light beam. The scheme may provide a promising candidate for future ultrafast all-optical signal processing applications.     

All-optical sampling exploiting nonlinear polarization rotation in a single semiconductor optical amplifier

An all-optical sampling scheme using a single semiconductor optical amplifier is proposed for analog signal processing. The analog optical signal is sampled by the probe pulse train through the nonlinear polarization rotation arising in the semiconductor optical amplifier. Conversion efficiency and total harmonic distortion are presented to evaluate the sampling linearity. In the experiment, 40 GSa/s all-optical sampling for 2.5 GHz analog optical signal is successfully demonstrated with commercially available fiber-pigtailed components. The results show that the fundamental conversion efficiency and the total harmonic distortion are 1.35 and 2.01% at the operating power of 5 mW, respectively. The proposed all-optical sampling requires only one semiconductor optical amplifier and has low power consumption, which is simple and has potential for photonic integration.     

All-optical quaternary circuits using quaternary T-gate

In multi-valued logic (radix>2), quaternary multiplexer (also known as T-gate) places a significant role for data transmission and signal processing. Four valued multiplexer transmit one data (from 4-input) to the output corresponding to the one selected input. Any four-valued logic can be implemented using T-gate. So it is called ‘universal’ element. In this paper some all-optical quaternary logical operations, quaternary half-adder, quaternary multiplier and quaternary comparator is proposed and described using only all-optical quaternary T-gate.     

A method of generating single optical pulse in nanosecond range with the joint uses of electro-optic modulator and nonlinear material

Optics has already been established as a successful candidate in data processing. Lots of all-optical data processors are proposed in the last few decades. Again it is well-known that, in many situations, an optical single pulse is very much useful to trigger an optical data processing circuit. In this communication the authors propose a method of generating a sub-nanosecond optical pulse using electro-optic modulator and nonlinear material.     

一种基于半导体光放大器马赫-曾德尔干涉仪的新型全光信头和净荷分离方案

提出一种新型的光分组信头净荷分离方案.利用一个非对称半导体光放大器马赫－曾德尔干涉仪提取出信头脉冲,然后再利用对称的SOA-MZIs构建异或门,完成信头脉冲和光分组脉冲在差分调制下的逻辑运算,提取出净荷脉冲.在50 Gb/s速率下,数值仿真表明提取出的信头和净荷信号的开关比均超过16 dB.此外通过更改参数设置.该方案还可以应用到不同速率,不同信头长度的信头净荷分离中.     

Polarization encoded all-optical quaternary R-S flip-flop using binary latch

The developments of different multi-valued logic (MVL) systems have received considerable interests in recent years all over the world. In electronics, efforts have already been made to incorporate multi-valued system in logic and arithmetic data processing. But, very little efforts have been given in realization of MVL with optics. In this paper we present novel designs of certain all-optical circuits that can be used for realizing multi-valued logic functions. Polarization encoded all-optical quaternary (4-valued) R-S flip-flop is proposed and described. Two key circuits (all-optical encoder/decoder and a binary latch) are designed first. They are used to realize quaternary flip-flop in all-optical domain. Here the different quaternary logical states are represented by different polarized state of light. Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch can take an important role. Computer simulation result confirming described methods and conclusion are given in this paper.     

Mach-Zehnder interferometer-based all-optical reversible logic gate

In recent years, reversible logic has emerged as a promising computing paradigm having application in low-power CMOS, quantum computing, nanotechnology and optical computing. Optical logic gates have the potential to work at macroscopic (light pulses carry information), or quantum (single photons carry information) levels with great efficiency. However, relatively little has been published on designing reversible logic circuits in all-optical domain. In this paper, we propose and design a novel scheme of Toffoli and Feynman gates in all-optical domain. We have described their principle of operations and used a theoretical model to assist this task, finally confirming through numerical simulations. Semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometer (MZI) can play a significant role in this field of ultra-fast all-optical signal processing. The all-optical reversible circuits presented in this paper will be useful to perform different arithmetic (full adder, BCD adder) and logical (realization of Boolean function) operations in the domain of reversible logic-based information processing.     

Method of developing an all optical wavelength encoded single bit comparator exploiting four wave mixing and wavelength filtering character of nonlinear semiconductor optical amplifiers

Data Comparator is the integral part of arithmetic and logical unit of any electronic or optical data processor. Due to some inherent limitations of electronics it is not possible to obtain super fast data processing (over Terahertz limit) from electronic comparator. Again frequency encoding technique has been established as an excellent one over the other optical data encoding techniques. Semiconductor optical amplifiers (SOA) technologies have shown its potentiality of realising many all-optical systems. In this communication the authors have proposed a new all-optical wavelength encoded single bit binary comparator exploiting the four wave mixing and wavelength filtering property of nonlinear semiconductor optical amplifier.     

All- optical phase encoded 4-to-1 phase multiplexer using four wave mixing in semiconductor optical amplifier

Optics has already showed its potency over its electronic complements in case of superfast computing and communication systems. Semiconductor optical amplifier, (SOA) with its several nonlinear properties, plays a very crucial role in the development of high-speed all-optical processor. Multiplexer and demultiplexer are the extremely important element of the processor which takes part in utilizing different actions like encoding, decoding, routing, and the different process of data conversion and generation, etc. In this paper, the authors have proposed a scheme of phase encoded all-optical phase multiplexer using four wave mixing (FWM) property of semiconductor optical amplifier. Thus, the improved tolerance against fiber-nonlinearity and higher receiver sensitivity of phase encoding method with the fast occurring processes like FWM in SOA offers higher speed in this proposed scheme of multiplexing.     

All-optical method for maintaining a fixed intensity level of a light signal in optical computation

In data and image processing the role of optics is already well established. Due to inherent parallelism the optical systems run faster than its electronic counterparts. Optical nonlinear material can be used as a successful optical switch. The primary requirement for proper functioning of such nonlinear material based logic devices is a fixed intensity level of the optical signal against a specific logic state. In this communication, the authors propose a new concept to obtain a fixed intensity level of optical signal against a specific logic state for data processing. The scheme may extend a tremendous application not only to the area of all-optical computation, but also to optical communication process.     

An all-optical parallel scheme for the exclusive-or operation

In this letter, we propose an all-optical parallel scheme for the exclusive-or (XOR) logic processing, in which the bright and dark pixels of an image source are adopted to represent the binary data. Two orthogonally polarized coherent light beams are overlapped using a 50/50 beam splitter, and are then checked using a polarization analyzer. The distribution of light intensity of final output image is the result of the XOR logic operation on the input pixels.