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.     

All-optical carry lookahead adder with the help of terahertz optical asymmetric demultiplexer

An all-optical model of carry lookahead adder (CLA) implemented with a semiconductor optical amplifier (SOA)-assisted Sagnac interferometer (TOAD) is presented. The model accounts for the SOA small signal gain, linewidth enhancement factor, the switching pulses energy and width and the Sagnac loop asymmetry. Adder is a very basic component in a central processing unit. The CLA is the highest speed adder nowadays. Theoritical model is presented and verified through numerical simulation. The method promises both higher processing speed and accuracy. The model can be enhanced the functionality in which carry lookahead adder is the basic building block.     

All-optical adder/subtractor based on terahertz optical asymmetric demultiplexer

An all-optical adder/subtractor （A/S） unit with the （TOAD） is proposed. The all-optical A/S unit with help of terahertz optical asymmetric demultiplexer a set of all-optical full-adders and optical exclusive- ORs （XORs）, can be used to perform a fast central processor unit using optical hardware components. We try to exploit the advantages of TOAD-based optical switch to design an integrated all-optical circuit which can perform binary addition and subtraction. With computer simulation results confirming the described methods, conclusions are given.     

Optical computation based on nonlinear total reflectional optical switch at the interface

A new scheme of binary half adder and full adder is proposed. It realizes a kind of all-optical computation which is based on the polarization coding technique and the nonlinear total reflectional optical switches.      

Circuit designs of ultra-fast all-optical modified signed-digit adders using semiconductor optical amplifier and Mach-Zehnder interferometer

The need for increasingly high-speed digital optical systems and optical processors demands ultra-fast all-optical logic and arithmetic units. In this paper, we combine the attractive and powerful parallelism property of the modified signed-digit (MSD) number representation with the ultra-fast all-optical switching property of the semiconductor optical amplifier and Mach-Zehnder interferometer (SOA-MZI) to design and implement all-optical MSD adder/subtracter circuits. Non-minimized and minimized techniques are presented to design and realize efficient circuits to perform arithmetic operations. Several all-optical circuits’ designs are proposed with the objective to minimize the number of the SOA-MZI switches, the time delay units in the adders, and other optical elements. To use the switching property of the SOA-MZI structure, two bits per digit binary encoding for each of the trinary MSD digits are used. The proposed optical circuits will be very helpful in developing hardware modules for optical digital computing processors.     

A new method of binary addition scheme with massive use of non-linear material based system

The limitations in electronics in arithmetic, algebraic & logic processing are well known. Very high speed performance (above GHz) are not expected at all in conventional electronic mechanism. To achieve high speed performance we may think on the introduction of optics instead of electronics for information, processing and computing. Non-linear optical material is a successful candidate in this regard to play a major role in the optically controlled switching systems and therefore in all-optical parallel computation these materials can show a very good potential aspect. In this paper, we have proposed a new method of an optical half adder as well as full adder circuit for binary addition using non-linear and linear optical materials.     

Ultra-fast all-optical polarization-encoded modified signed-digit addition using terahertz-optical-asymmetric-demultiplexer (TOAD) switches

In this paper, enhanced designs for ultra-fast all-optical circuits based on the terahertz-optical-asymmetric-demultiplexer (TOAD) adders are proposed. The high speed is achieved due to the use of the nonlinear optical materials and the nonbinary modified signed-digit (MSD) number representation. The proposed all-optical circuits use polarized light to present the trinary digits of the MSD numbers. It will be shown that the polarization-encoded MSD adder uses much less TOADs switches (37.5% less) and it is faster by 33.33% compared to the intensity-encoded ones.     

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.     

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.     

Passive, “self-trapped family” all-optical half adder using all-optical XOR and AND gates

The paper presents an alternative novel approach to obtain all-optical logic. We show that XOR, NOT, and AND logic could be obtained by appropriately setting parameter of all-optical passive transistor. An AND gate followed by NOT gives NAND logic (building block) that, in principle can provide complete set of passive, fiber compatible “self-trapped family” all-optical logic gates (with Boolean completeness) and may find many possibilities in the area of all-optical computing. To give one example, we propose all-optical half adder.     

Optical arithmetic unit using bit-WDM

A novel arithmetic unit is proposed consisting of a pipelined optical ripple carry adder that adds two words with bits multiplexed by different wavelengths on a single fiber. The addition result is returned to a fiber bus in the same format as the incoming words. The corresponding operand bit pairs are split off the fiber using wavelength division demultiplexers. Full adders compute the sum for each bit pair and the carry from the next lower significant bit pair. The full adder uses couplers and NOT, NOR and novel XOR logic gates constructed using semiconductor optical amplifiers for gain and wavelength shifting.     

Optical phase erasure and its application to format conversion through cascaded second-order processes in periodically poled lithium niobate

We describe a new optical phase erasure characteristic of periodically poled lithium niobate (PPLN) by using cascaded second-harmonic generation and difference-frequency generation with the signal set at the quasi-phase-matching wavelength. A simple analytical expression is derived clearly explaining the operation principle. It is interesting that the optical phase erasure feature enables an all-optical format conversion from carrier-suppressed return to zero (CSRZ) to return to zero (RZ). We experimentally and theoretically demonstrate a PPLN-based 40 Gbits/s all-optical CSRZ-to-RZ format conversion. Moreover, tunable and multicasting CSRZ-to-RZ format conversions are also verified in the experiment.     

Ultra-high speed all-optical shift registers and their applications in OTDM networks

All-optical shift registers are basic building modules for the development of ultra-high speed optical time division multiplexing networks. In this paper, we review the progress that has been made in this cutting-edge technology, focusing on implementations that exploit the attractive features of semiconductor optical amplifier (SOA)-based interferometric configurations. We present regenerative storage performed with an all-optical recirculating shift register with an inverter at 10 Gb/s using a SOA-assisted Sagnac switch and a second SOA to provide feedback. We demonstrate also an all-optical memory based on the SOA-assisted Ultrafast Nonlinear Interferometer capable of reading/writing 20 Gb/s packets of variable length without data inversion. These registers can find application in the development of two nontrivial complex all-optical circuits of enhanced functionality. The first is an all-optical pseudorandom binary sequence generator for which we describe an efficient design algorithm and propose ways for monitoring and verification. The second is an all-optical error counter for which we address the error detection and evaluation issues using a novel sampling technique. These circuits are key elements for the implementation of a high-speed, all-optical bit error rate tester (BERT), which has the potential to outperform its electronic equivalent and constitute a possible new product for the telecommunications industry.     

Optical Module for Modified Signed-Digit Computing Based on Bit Plane Encoding and Pattern Operations

We propose here a new optical modified signed-digit (MSD) adder module based on bit plane pattern encoding of MSD digits and pattern operations. The pattern operations required in the algorithm are duplication, combination and shifting. They are simply performed by using optical components such as beam splitters, mirrors and parallel plates, instead of optical logic arrays. An optical MSD adder module comprised of six properly interacting blocks with all optical components packaged on a common substrate is presented in detail. We analyze the system errors caused by manufacture and alignment of optical components, the information throughput, the intensity nonuniformity and the system volume of the adder module.     

All-optical regenerative memory for long term data storage

We describe a novel all-optical regenerative memory comprising two nonlinear optical switching gates coupled by an optical fibre storage loop. Binary pulse patterns were stored in the memory circuit for periods of several hours. This long term storage corresponds to > 10 billion circulations around the fibre storage loop.     

Turbo-switched Mach-Zehnder interferometer performance as all-optical signal processing element at 160 Gb/s

Two variations of the active Mach-Zehnder interferometer (MZI) that incorporate the recently proposed turbo-switch effect are introduced to carry out three key functionalities in forthcoming high-speed optical telecommunication networks, namely, all-optical wavelength conversion, photonic XOR gating and optical time-division demultiplexing. Their performance is numerically investigated at 160 Gb/s using a sophisticated semiconductor optical amplifier (SOA) model. The more practical of the two proposed geometries shows error-free operation as XOR Boolean gate, low patterning as wavelength converter, and poor performance as demultiplexer. For comparison, results derived from well-accepted (or typical) schemes are also presented, and the role of the required extra SOAs as distinguishing elements of the new architectures is investigated.     

基于细菌视紫红质膜的全光逻辑门

基于在细菌视紫红质膜中的自衍射，我们提出了全光非、异或、半加器及同或门逻辑操作。利用衍射光与记录光偏振状态之间的关系，我们演示了非门和同或门逻辑操作。 通过衍射光，记录光和读出光之间的偏振状态的关系，我们实现了异或逻辑操作和具有三个输入端的半加器逻辑操作。所用方法简单实用。     

An all-optical WDM-to-TDM conversion scheme with simultaneous all-optical synchronization for WDM/OTDM network nodes

We present an all-optical WDM-to-TDM conversion scheme with simultaneous all-optical synchronization that can be utilized in switching nodes of very high-speed WDM/OTDM hybrid communication systems. The scheme, which utilizes a nonlinear optical loop mirror in conjunction with a synchronously modelocked semiconductor laser, is experimentally demonstrated by WDM-to-TDM conversion of two optical channels in a switching node. The optical time division multiplexed output has a potential total throughput of ≈40 Gb/s. This all-optical scheme removes limitations of restricted bandwidth of electronics at switching nodes and also has advantages over existing optical time division multiplexing schemes.     

All-optical reconfigurable logic operations with the help of terahertz optical asymmetric demultiplexer

An all-optical reconfigurable logic operation essentially constitutes a key technology for avoiding complex and speed limited optoelectronics conversions and performing various processing tasks. All-optical reconfigurable logic operations with the help of terahertz optical asymmetric demultiplexer (TOAD) is proposed and described. The paper describes the all-optical reconfigurable logic operations using a set of all-optical multiplexer and optical switches. We have tried to exploit the advantages of TOAD-based switch to design an integrated all-optical circuit which can perform the different logic operations AND, XOR, NOR and NOT. Numerical simulation confirming described methods is given in this paper.     

基于SOA-Sagnac干涉仪的XPM全光波长变换的研究

对基于SOA-Sagnac干涉仪的XPM个光波长变换从理论上和实验上进行了较为详细的研究。根据光路合成法求出SOA-Sagnac干涉仪的化输函数，并导出波长变换后的探测光电场表达式，并构成了一套实验系统，进行了622Mbit／s归零码光脉冲的波长变换实验，获得消光比大于10dB的波长变换范围约为43nm。