Investigation of Deuterium Substitution Effects in a Polymer Membrane Using IR Fourier Spectrometry

Since last few decades optics has already proved its strong potentiality for conducting parallel logic, arithmetic and algebraic operations due to its super-fast speed in communication and computation. So many different logical and sequential operations using all optical frequency encoding technique have been proposed by several authors. Here, we have keened out all optical dibit representation technique, which has the advantages of high speed operation as well as reducing the bit error problem. Exploiting this phenomenon, we have proposed all optical frequency encoded dibit based XOR and XNOR logic gates using the optical switches like add/drop multiplexer (ADM) and reflected semiconductor optical amplifier (RSOA). Also the operations of these gates have been verified through proper simulation using MATLAB (R2008a).     

Alternating approach of implementing frequency encoded all-optical logic gates and flip-flop using semiconductor optical amplifier

In conduction of parallel logic, arithmetic and algebraic operations, optics has already proved its successful role. Since last few decades a number of established methods on optical data processing were proposed and to implement such processors different data encoding/decoding techniques have also been reported. Currently frequency encoding technique is found be a promising as well as a faithful mechanism for the conversion of all-optical processing as the frequency of light remains unaltered after refection, refraction, absorption, etc. during the transmission of light. There are already proposed some frequency encoded optical logic gates. In this communication the authors propose a new and different concept of frequency encoded optical logic gates and optical flip-flop using the non-linear function of semiconductor optical amplifier.     

An alternative approach of developing a frequency encoded optical tri-state multiplexer with broad area semiconductor optical amplifier (BSOA)

During the last few decades several logic gates, sequential and combinational logic devices, have been developed using light signals. For this work several encoding as well as decoding techniques are proposed for data handling and information processing with optics as information carrying signal. Frequency encoding technique is one such type of encoding processes, which gives a very good response for long distance communication of logically processed data because frequency is a fundamental character of light and it remains unchanged for long distance communication. Here in this paper the authors propose a frequency encoded multiplexer with the proper use of semiconductor optical amplifier in tri-state logic.     

A novel frequency encoded all optical logic gates exploiting polarization insesensitive four wave mixing in semiconductor optical amplifier, filtering property of ADD/DROP multiplexer and non-linearity of reflective semiconductor amplifier

All optical logic gates exploiting polarization independent four wave mixing in semiconductor optical amplifier (SOA), filtering property of ADD/DROP multiplexer (ADM) and non-linearity in reflective semiconductor optical amplifier (RSOA) have been proposed. The logic gates proposed are polarization independent which ensures hardware simplicity and greater speed. The all optical frequency encoded logic gates NOT, OR, NOR, AND, NAND, X-OR, X-NOR are implemented which are very useful in optical computing ad signal processing, cryptography, etc. The logic gates proposed have the advantages that there is no intensity loss dependent problem, and are polarization and temperature insensitive.     

Analytical and simulative studies on optical NOR and controlled NOR logic gates with semiconductor optical amplifier

Semiconductor optical amplifier (SOA) is used for different successful frequency based switching operations. In this paper the authors describe the simulation study of the performances of SOA in various optical switches like frequency conversion, add-drop multiplexer and frequency encoded optical NOR gate, which is one the most important gates in logic family as it is known as one of the universal logic gates. Again, the controlled optical NOR logic operation with semiconductor optical amplifier is also proposed in this paper.     

All-optical method of developing some fundamental and functional quaternary logic gates

All optical multivalued logic processors are of paramount importance in optical computing and signal processing. In this article the author proposes a method of developing all-optical quaternary Inversion, NOT and Bitswap logic gates, which are essential parts of quaternary arithmetic and logical processors. Nonlinear switching and add/drop multiplexing (ADM) properties of semiconductor optical amplifier (SOA) are exploited here to develop the frequency encoded quaternary logic gates.     

An all optical method of implementing a wavelength encoded simultaneous binary full adder-full subtractor unit exploiting nonlinear polarization rotation in semiconductor optical amplifier

Full adders and full subtractors are the basic circuit elements of any digital data processor in electronics as well as in the all optical domain. Again the wavelength dependent encoding/decoding techniques have established itself as a very promising and efficient tool having some inherent and unique advantages relative to the other well known intensity or polarization or phase dependent optical data encoding mechanisms. In this communication, the authors therefore propose a new scheme of implementing a wavelength encoded complete binary full adder-full subtractor unit in the all optical domain using the wavelength conversion by the nonlinear polarization rotation in a single semiconductor optical amplifier. The interacting signals are counter propagating in the semiconductor optical amplifier and hence can be set at the same wavelength. To realize the binary logic wavelength dependent encoding/decoding mechanism is exploited in our proposed scheme of full adder-full subtractor unit. Also the optical add/drop multiplexing employing the special filtering property of the semiconductor optical amplifier is utilized for the designing of the all optical system.     

Realization optical signal processing components using SOA

This paper simulated simultaneously AND and NOT logic gate with frequency converter by using semiconductor optical amplifier. These logic gates and frequency converter are obtained with SOA effects like XGM and FWM of signals. Simulative realization of these logic gates and frequency converter will lead revolution in optical signal processing for high speed operation.     

Effect of amplified spontaneous emission on semiconductor optical amplifier based all-optical logic

The performances of all-optical logic gates XOR, AND, OR, NOR and NAND based on semiconductor optical amplifier (SOA) have been simulated including the effects of amplified spontaneous emission (ASE). For the parameters used, all-optical logic gates using SOA are capable of operating at speed of 80 Gb/s.     

Analytical approach of developing wavelength encoded AND, NAND and X-OR logic operations and implementation of the theory using semiconductor optical amplifiers

Frequency encoding technique is a very promising and faithful technology for very fast long-haul optical communication and super fast computation. Implementation of different logic gates based on the principle of frequency conversion is the key mechanism of frequency encoded data processing and networking. It is established that semiconductor optical amplifiers (SOA) have been used successfully for the purpose of frequency conversion. One of the important techniques of frequency conversion is the conjugate beam generation by four wave mixing (FWM) in SOA and ultimately conversion of it into desired frequency by means of reflecting semiconductor optical amplifier (RSOA). However the efficiency of conjugate beam generation is restricted by polarization dependent gain saturation of SOA. This dependency can be successfully removed using polarization diversity scheme. Another technique of the frequency conversion is based on nonlinear rotation of the state of polarization of the linearly polarized probe beam. An important advantage of using polarization rotation in SOA is that a small change in rotation of the state of polarization will lead to a large difference in output power. Here in our present communication we propose a method of developing wavelength encoded AND, NAND and X-OR logic operations exploiting the above mentioned functions of SOA. For this purpose we have developed an analytical treatment based on which above mentioned three logic gates are conducted. The satisfactory simulation result proves also the validity of the developed theory.     

Method of implementing frequency-encoded NOT,OR and NOR logic operations using lithium niobate waveguide and reflecting semiconductor optical amplifiers

Optics has already proved its strong potentiality for the conduction of parallel logic, arithmetic and algebraic operations. In the last few decades several all-optical data processors were proposed. To implement these processors different data encoding/decoding techniques have been reported. In this context, polarization encoding technique, intensitybased encoding technique, tristate and quaternary logic operation, multivalued logic operations, symbolic substitution techniques etc. may be mentioned. Very recently, frequency encoding/decoding technique has drawn interest from the scientific community. Frequency is the fundamental character of any signal; and it remains unaltered in reflection, refraction, absorption etc. during the propagation and transmission of the signal. This is the most important advantage of frequency encoding technique over the conventional encoding techniques. In this communication the authors propose a new scheme for implementing NOT, OR and NOR logic operations. For this purpose co-propagating beams having different frequencies in C-band (1535–1560 nm) have been used for generating cascaded sum and difference frequency, exploiting the nonlinear response character of periodically poled LiNbO₃ waveguide. The cross-gain modulation property of the semiconductor optical amplifier (SOA) and the wavelength conversion property of the reflecting semiconductor optical amplifiers (RSOA) are exploited here to implement the desired optical logic and arithmetic operations.     

基于单个半导体光放大器的高速多功能逻辑门

采用半导体光放大器(SOA)中的非线性效应可以实现多种多样的高速全光信号处理. 利用SOA的非线性效应(包括四波混频、交叉增益调制、瞬态交叉相位调制等)实现了多种功能的逻辑运算,包括“与”、“或非”、“同或”、“或”和“非”. 由于SOA用于全光信号处理的调制速率受到增益恢复时间较慢的限制而无法实现高速的信号处理,在SOA后面级联一个带宽为0.32nm的失谐滤波器可以提高SOA的工作速率,仅用一个SOA实现了40Gbit/s的多功能逻辑门. 关键词： 半导体光放大器 全光逻辑门 瞬态交叉相位调制     

All-optical XNOR and AND gates simultaneously realized in a single semiconductor optical amplifier with improved dynamics

All-optical XNOR and AND logic gates using four-wave mixing (FWM) and cross-gain modulation (XGM) in a single semiconductor optical amplifier (SOA) with improved dynamics are simultaneously realized. By numerical simulation, the effects of the input optical wave powers and injection current on the critical factors of the logic gate performances, such as the ON--OFF contrast ratio, the power-output level of the logic `1', and the difference between power outputs of the logic `1', are investigated in detail. In addition, the effect of the counter-propagating CW pump on the gain recovery is analysed.     

A novel method of developing all-optical frequency encoded memory unit exploiting nonlinear switching character of semiconductor optical amplifier

The very fast running optical memory and optical logic gates are the basic building blocks for any optical computing data processing system. Realization of a very fast memory-cell in the optical domain is very challenging. In the last two decades many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitation because of low switching response of the active devices. In our present communication the authors propose a method of developing a frequency encoded memory unit based on the switching action of semiconductor optical amplifier (SOA). Nonlinear polarization rotation characters of SOA and ‘SOA based Mach-Zehnder Interferometer’ switch, i.e. ‘SOA-MZI’ switch, are exploited for the purpose of some switching action with least switching power (<−3 dB_m) and high switching contrast ratio (20 dB). Here two logic states (‘0’ state and ‘1’ state) of the memory is encoded by two different frequencies, which will remain unchanged throughout the data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. Though the SOA based switch runs with the operational speed 100 Gb/s, still due to the presence of the other optical components in the memory unit, the overall speed of the proposed system will come down to 10 Gb/s.     

Design and analysis of an all-optical processor for modular arithmetic

We present a logical design of an all-optical processor that performs modular arithmetic. The overall design is based a set of interconnected modules that use all-optical gates to perform simple logical functions. The all-optical logic gates are based on the semiconductor optical amplifier nonlinear loop. Simulation results are presented and some practical design issues are discussed.     

Optimization of regenerator based on semiconductor optical amplifier for degraded differential phase shift keying signal

Real time phase regeneration is necessary for degraded phase modulation format optical communication systems.A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in recent years.In this paper,for this type of regenerator,its optimal working condition is found by solving the dynamic equations which describe the variance of the optical field and carrier density in the semiconductor optical amplifier by the finite difference method.The results show that the optimal improvement of signal Q factor can reach more than 2.2 dB.     

A method of developing wavelength encoded all-optical S–R flip-flop by the uses of semiconductor optical amplifier based Mach–Zenhder interferometer and phase conjugation system

A scheme for a high-speed wavelength encoded all-optical S–R flip-flop (or a digital memory cell for storing of optical bits) based on wavelength conversion (MZI) in semiconductor optical amplifier (SOA) and phase conjugation system (PCS) is proposed. The switching action of semiconductor optical amplifier (SOA) does not give too high operational speed because of electrical pumping power. But optical phase conjugation mechanism gives us ultrahigh operational speed. So, joint use of them gives rise to a more high speed system comparatively to only SOA based switches. Here two logic states of the whole system is encoded by two wavelengths as well as frequencies, since the information in the bit is unaffected throughout the communication not having regard to the loss of light energy due to reflection, refraction polarization, etc.     

Simultaneous implementation of all-optical OR and AND logic gates for NRZ/RZ/CSRZ ON-OFF-keying signals

An all-optical scheme for simultaneously realizing OR and AND logic gates based on three-input four-wave mixing (FWM) arising in a single semiconductor optical amplifier (SOA) is proposed and demonstrated. It has the ability to process not only conventional non-return-to-zero-ON-OFF-keying (NRZ-OOK) and return-to-zero-OOK (RZ-OOK) formats but also carrier-suppressed return-to-zero-OOK (CSRZ-OOK) format signals. Firstly, the performance of 40 Gb/s logic operation is numerically evaluated by a comprehensive dynamic SOA model considering three input signal induced FWM effect. Then, 10 Gb/s experimental demonstrations with clear waveforms and high extinction ratios (ERs) further verify the logic integrity of this scheme. Thus, the OR and AND logic gates simultaneously achieved within a single logic unit is compact and cost-effective for future optical signal processing applications.     

All optical logic NAND gate based on two-photon absorption in semiconductor optical amplifiers

We propose a new scheme to realize all optical logic NAND operating at high speeds up to 250 Gb/s utilizing the ultrafast phase response during two-photon absorption (TPA) process in semiconductor optical amplifiers (SOA). NAND gate is important because other Boolean logic elements and circuits can be realized using NAND gates as basic building blocks. Rate equations for semiconductor optical amplifiers (for input data signals with high intensity) configured in the form of a Mach-Zehnder interferometer have been solved. The input intensities are high enough so that the two-photon induced phase change is larger than the regular gain induced phase change. The performance of this scheme is analyzed by calculating the quality factor of the resulting data streams. The results show that both AND and NAND operations at 250 Gb/s with good signal to noise ratio are feasible.     

Photonic crystal-based all-optical arithmetic circuits without SOA-based switches

Various proposed optical computing devices involve nonlinear optical operation and use semiconductor optical amplifier (SOA)-based switches as fundamental elements for logic operations. Due to the nonlinear operation, these devices suffer from high power that causes problems in very large-scale optical integration. In this paper, a method is proposed to implement arithmetic operations using a photonic crystal (PhC) cell and eliminate the SOA-based switches altogether. The proposed method is employed on designing an all-optical full adder/subtractor circuit that requires only beam combiners and photonic crystal NOT gates.