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.     

Canonical quaternary signed-digit arithmetic using optoelectronics symbolic substitution

A higher radix based signed-digit number system, such as the quaternary signed-digit (QSD) number system, allows higher information storage density, less complexity, fewer system components, and fewer cascaded gates and operations. An optoelectronics symbolic substitution scheme to handle the parallel quaternary signed-digit (QSD) arithmetic operations is proposed. A conversion algorithm is employed on the QSD numbers to simplify the addition process and reduce the number of the optical symbolic substitution rules. The optical addition operation of two QSD numbers is performed in one-step. An efficient shared content-addressable memory (SCAM)-based optical implementation of the QSD addition/subtraction operations employs a fixed number of minterms for any operand length. The canonical QSD number addition/subtraction scheme requires a significantly reduced number of minterms when compared with a similar previously reported technique.     

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.     

Trinary arithmetic and logic unit (TALU) using savart plate and spatial light modulator (SLM) suitable for optical computation in multivalued logic

Arithmetic logic unit (ALU) is the most important unit in any computing system. Optical computing is becoming popular day-by-day because of its ultrahigh processing speed and huge data handling capability. Obviously for the fast processing we need the optical TALU compatible with the multivalued logic. In this regard we are communicating the trinary arithmetic and logic unit (TALU) in modified trinary number (MTN) system, which is suitable for the optical computation and other applications in multivalued logic system. Here the savart plate and spatial light modulator (SLM) based optoelectronic circuits have been used to exploit the optical tree architecture (OTA) in optical interconnection network.     

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.     

Optoelectronic symbolic substitution based canonical modified signed-digit arithmetic

A single-step optoelectronics symbolic substitution scheme to handle parallel modified signed-digit (MSD) arithmetic operations is proposed. Conversion algorithms from MSD numbers into a canonical MSD representation are provided. The canonical MSD numbers have the property that no two consecutive digits are non-zero. The addition operation of two CMSD numbers is performed in one step. It will be shown that through the use of CMSD representation, the number of symbolic substitution rules in an optical content-addressable memory (CAM) based system is significantly reduced. The number of symbolic substitution rules can be further reduced to an optimum value through a proposed shared content-addressable memory optical set-up. Further, the proposed optical scheme doubles the storage efficiency of the shared content-addressable memory.     

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.     

A novel all optical method of implementing an n-bit wavelength encoded complete digital data comparator using 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 cannot be possible to obtain a super fast operation (over terahertz limit) from electronic comparators. Again wavelength encoding technique has been established as an excellent one over other existing optical data encoding techniques. Semiconductor optical amplifier (SOA) technologies have shown their strong potentiality of realizing many all-optical systems. In this communication the authors have proposed a new scheme of developing all-optical wavelength encoded n bit binary comparator exploiting the four-wave mixing, wavelength filtering, wavelength conversion and nonlinear polarization rotation capabilities property of nonlinear semiconductor optical amplifiers. The scheme can be used for comparing signed and unsigned optical binary data of any bit wide numbers as well. The comparator is especially suitable for use as a building block in a larger optical circuit, such as in an all optical telecommunications switch.     

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 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.     

A new scheme of all-optical adder logic operation based on nonlinear property of the material and polarization encoding technique

Optical nonlinear materials have been used for several digital logic and arithmetic operations. These operations are conducted in real time domain as per their operational speed is concerned. In this paper authors propose a new method of all optical half adder scheme. This type of switching is based on polarization properties of light along with nonlinear properties of material. As the state of polarization of light ensures that the field intensity level of the light signal is the same in whole operation, the scheme may be extended to some wide applications in all optical parallel computation and information processing.     

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.     

Modified signed-digit addition by using binary logic operations and its optoelectronic implementation

In this work, a three-step modified signed-digit (MSD) addition by using binary logic operations is proposed. Each input digit is encoded with two binary bits. Through binary logic operations, all of the weight and transfer digits and the final sum digits represented with the same encoding scheme will be generated. The operations can be performed at each digit position in parallel. In our suggested optical arithmetic and logic unit (ALU), a single electron trapping (ET) device is employed to serve as the binary logic device. This technique based on ET logic possesses the advantage of high signal-to-noise ratio (SNR). The optoelectronic system can be constructed in a simple, compact and general-purpose form.     

Ternary Galois field arithmetic operations with optical nonlinear material (OPNLM) switch

Ternary Galois field (GF3) arithmetic can take an important and significant role in future information processing with multi-valued logic (MVL). An all optical circuit for two arithmetical operations (addition and multiplication) in ternary Galois field with OPNLM switch is proposed and discussed. The different states of polarization of light are taken as different logic states. An outline of Ternary Galois field sum of product (TGFSOP) is also discussed. Mathematical simulation has confirmed the result.     

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.     

Parallel quaternary signed-digit arithmetic operations: addition, subtraction, multiplication and division

A quaternary signed-digit number representations-based arithmetic unit is proposed. The arithmetic unit performs parallel one-step addition (subtraction), multiplication and division. We use the symbolic substitution technique to reduce the number of the computation rules involved in the computation rules. Fast parallel nonrecoded quaternary signed-digit multiplication is proposed using our proposed one-step quaternary signed-digit adder. Also, parallel quaternary signed-digit division is performed in constant time by exploiting an iterative conversion algorithm where in every iterative step a negation operation, an addition operation and two multiplication operations are performed. The execution times of the proposed QSD operations are proportional to log₂ n, where n are the length of operands.     

One-step optical trinary signed-digit arithmetic using redundant bit representations

A simple one-step fully parallel trinary signed-digit arithmetic is proposed for parallel optical computing. This technique performs multidigit carry-free addition and borrow-free subtraction in constant time. The trinary signed-digit arithmetic operations are based on redundant bit representation of the digits. Optical implementation of the proposed arithmetic can be carried out using correlation or matrix multiplication based schemes. An efficient matrix multiplication based optical implementation that employs a fixed number of minterms for any operand length is developed. It is shown that only 30 minterms (less than recently reported techniques) are enough for implementing the one-step trinary addition and subtraction.     

Method of all-optical frequency-encoded binary adder system using nonlinear waveguide and reflecting semiconductor optical amplifiers

Arithmetic and algebraic operations are the most important part of optical computation and data processing. To implement the optical logic operations, different data encoding/decoding techniques have been reported. Frequency variant encoding/decoding technique is now performing a very faithful role in this regard. Frequency is the fundamental character of any signal and it remains unaltered in reflection, refraction, absorption, etc. during propagation and transmission of the signal. This is the most potential advantage of the frequency encoding technique over any other conventional encoding techniques. Here, in our proposed scheme of addition of binary bits made of two encoded frequencies in C-band (1535-1560 nm), the conjugate beam is generated in LiNbO₃ waveguide using cascaded sum and difference frequency generation by the nonlinear interaction with a third frequency, exploiting the nonlinear response character of periodically poled LiNbO₃ waveguide. The cross-gain modulation property of reflecting semiconductor optical amplifier (RSOA) has also been exploited here for frequency conversion purposes.     

A method of developing all-optical mono-stable multivibrator system exploiting the Kerr non-linearity of medium

Optics has already been established as a potential candidate for conduction of digital logic and arithmetic operation in communication and computation processes. Different proposals have been reported by different scientists to make optics meaningful signal for conduction of the above operations. As it is well known that the memory device is a basic building block of any computation and communication system hence developing systems such as digital memory, multivibrator, etc. are the obvious requirements for optical communication as well as computation systems also. As the role of switching devices is an essential part of any processing system, many proposals were seen where all-optical switches using the combination of linear and non-linear materials were used, to implement the logic elements.In this context, the authors propose a new scheme for implementation of an all-optical mono-stable multivibrator using the non-linear material based switches and high refractive index based material. This multivibrator can generate a time pulse of definite width.