Space-variant optical logic operations based on operation-dependent encoding method

We propose performing space-variant optical logic operations in a space-invariant optical system by selectively assigning encoding states that are operation dependent. With this method, encoders using liquid-crystal cells and liquid-crystal light valves to perform space-variant encoding for all 16 Boolean functions are designed. Multiple-instruction-multiple-data processing can then be realized in optical logic systems.     

Parallel optical negabinary arithmetic based on logic operations

On the basis of signed-digit negabinary representation, parallel two-step addition and one-step subtraction can be performed for arbitrary-length negabinary operands. The arithmetic is realized by signed logic operations and optically implemented by spatial encoding and decoding techniques. The proposed algorithm and optical system are simple, reliable, and practicable, and they have the property of parallel processing of two-dimensional data. This leads to an efficient design for the optical arithmetic and logic unit.     

Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation

A novel, to our knowledge, two-step digit-set-restricted modified signed-digit (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {1 , 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which can be summed to form the final result without carry generation. The operation can be performed in parallel by use of binary logic. An optical system that utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of data arrays, any complex logic operations of multiple variables can be realized without additional temporal latency of the intermediate results. This technique has a high space-bandwidth product and signal-to-noise ratio. The main structure can be stacked to construct a compact optoelectronic MSD adder-subtracter.     

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.     

Simple online recognition of optical data strings based on conservative optical logic

Optical packet switching relies on the ability of a system to recognize header information on an optical signal. Unless the headers are very short with large Hamming distances, optical correlation fails and optical logic becomes attractive because it can handle long headers with Hamming distances as low as 1. Unfortunately, the only optical logic gates fast enough to keep up with current communication speeds involve semiconductor optical amplifiers and do not lend themselves to the incorporation of large numbers of elements for header recognition and would consume a lot of power as well. The ideal system would operate at any bandwidth with no power consumption. We describe how to design and build such a system by using passive optical logic. This too leads to practical problems that we discuss. We show theoretically various ways to use optical interferometric logic for reliable recognition of long data streams such as headers in optical communication. In addition, we demonstrate one particularly simple experimental approach using interferometric coinc gates.     

Sensitive photonic crystal phase logic gates

Total optical phase logic gates are reported in this paper. They are constructed by coupled-defect photonic crystal after two problems are overcome by a heterostructure or an asymmetric structure. Both half and all-phase logic gates are discussed. The sensitivity of these total optical phase logic gates not only are two orders sensitive than those using amplitude-signal, but also have many other advantages: such as very low energy cost. By using such phase logic gates, only a continued wave laser with one frequency is sufficient to operate the phase logic gate or the whole optical integrated circuit.     

Implementation of high speed optical universal logic gates using the electro-optic effect-based Mach–Zehnder interferometer structures

The universal logic gates are the most important logic gates responsible for optimized design of different types of complex digital logic circuits. It is of great interest to implement the function of universal logic gates such as NAND and NOR logic gates using the concepts of electro-optic effect. The smart use of electro-optic effect can provide very effective optical power switching devices. The implementation of universal logic gates operation in the optical domain can improve the performance of the devices and includes the advantages of the optical communication system. The proper configuration of Mach–Zehnder interferometer working on the principle of electro-optic effect can provide the optical responses equivalent to the NAND and NOR logic gates. The proposed devices can be analyzed to check the various performance affecting parameters in order to specify the physical parameters.     

Programmable optical logic systems using free-space optical interconnections

A free-space optical logic technique is presented that utilizes a two-dimensional array of diffractive optical elements. Each optical element focuses light to multiple, separate positions in the output focal plane. The focal spots from different optical elements are allowed to overlap spatially, resulting in interference. By changing the phase shift between the optical elements, one can create different optical logic operations in the focal plane. The technique is demonstrated by the use of two input beams incident onto a multiplexed optical element written onto a programmable spatial light modulator. The optical element simultaneously creates both AND and XOR logic functions in the output plane.     

Study of all-optical logic XNOR gate based on XGM in linear optical amplifier

Future digital optical communication cannot develop without all-optical high-speed optical devices, especially in the field of high speed large capacity optical transmission, all-optical packet switching and optical computing, and thus optical logic devices are becoming a hotter spot of research. Based on the cross-gain modulation (XGM), a novel scheme of all-optical logic XNOR gate using linear optical amplifier (LOA) is presented in this paper. LOA results show a good gain characteristic, which can get better output logic operation than traditional semiconductor optical amplifier (SOA). Choosing suitable injection current, wavelength scope of the input signal and CW power can achieve better logic operation effect.     

Reconfigurable optical logic unit with a terahertz optical asymmetric demultiplexer and electro-optic switches

A reconfigurable optical logic unit that can execute any binary logic and arithmetic operation on the same hardware with different configurations is proposed. The design, based on cascaded terahertz optical asymmetric demultiplexer switches, introduces reconfigurability with the help of electro-optic switches. The model is simple and practicable.     

Real-time detection and elimination of nonorthogonality error in interference fringe processing

In the measurement system of interference fringe, the nonorthogonality error is a main error source that influences the precision and accuracy of the measurement system. The detection and elimination of the error has been an important target. A novel method that only uses the cross-zero detection and the counting is proposed to detect and eliminate the nonorthogonality error in real time. This method can be simply realized by means of the digital logic device, because it does not invoke trigonometric functions and inverse trigonometric functions. And it can be widely used in the bidirectional subdivision systems of a Moiré fringe and other optical instruments.     

Novel all-optical logic gate using an add/drop filter and intensity switch

A novel design of all-optical logic device is proposed. An all-optical logic device system composes of an optical intensity switch and add/drop filter. The intensity switch is formed to switch signal by using the relationship between refraction angle and signal intensity. In operation, two input signals are coupled into one with some coupling loss and attenuation, in which the combination of add/drop with intensity switch produces the optical logic gate. The advantage is that the proposed device can operate the high speed logic function. Moreover, it uses low power consumption. Furthermore, by using the extremely small component, this design can be put into a single chip. Finally, we have successfully produced the all-optical logic gate that can generate the accurate AND and NOT operation results.     

Phonon‐Assisted Electro‐Optical Switches and Logic Gates Based on Semiconductor Nanostructures

High‐performance nanostructured electro‐optical switches and logic gates are highly desirable as essential building blocks in integrated photonics. In contrast to silicon‐based optoelectronic devices, with their inherent indirect optical bandgap, weak light‐modulation mechanism, and sophisticated device configuration, direct‐bandgap‐semiconductor nanostructures with attractive electro‐optical properties are promising candidates for the construction of nanoscale optical switches for on‐chip photonic integrations. However, previously reported semiconductor‐nanostructure optical switches suffer from serious drawbacks such as high drive voltage, limited operation spectral range, and low modulation depth. High‐efficiency electro‐optical switches based on single CdS nanobelts with low drive voltage, ultra‐high on/off ratio, and broad operation wavelength range, properties resulting from unique electric‐field‐dependent phonon‐assisted optical transitions, are demonstrated. Furthermore, functional NOT, NOR, and NAND optical logic gates are demonstrated based on these switches. These switches and optical logic gates represent an important step toward integrated photonic circuits.     

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.     

A Novel Design of Octal-Valued Logic Full Adder Using Light Color State Model

Due to the demand of high computational speed for processing big data that requires complex data manipulations in a timely manner, the need for extending classical logic to construct new multi-valued optical models becomes a challenging and promising research area. This paper establishes a novel octal-valued logic design model with new optical gates construction based on the hypothesis of Light Color State Model to provide an efficient solution to the limitations of computational processing inherent in the electronics computing. We provide new mathematical definitions for both of the binary OR function and the PLUS operation in multi valued logic that is used as the basis of novel construction for the optical full adder model. Four case studies were used to assure the validity of the proposed adder. These cases proved that the proposed optical 8-valued logic models provide significantly more information to be packed within a single bit and therefore the abilities of data representation and processing is increased.     

Logic devices based on inductive Josephson logics

Inductive Josephson logic (IJL) is realized by using Josephson junctions as a kind of nonlinear inductance. The operational principle of inductive Josephson logic is studied from a very simple example and generalized to multiple Josephson inductive logic devices. Concepts offorward andbackward are introduced to describe the states of the operations. IJLs operate in terms of current or flux; they are suitable to be used in connection with other flux-control Josephson circuit devices such as DC SQUID or DCFP. Some circuit devices based on the principle of inductive Josephson logic are given as examples of IJL logic functions.     

Field-programmable logic devices with optical input-output

A field-programmable logic device (FPLD) with optical I/O is described. FPLD's with optical I/O can have their functionality specified in the field by means of downloading a control-bit stream and can be used in a wide range of applications, such as optical signal processing, optical image processing, and optical interconnects. Our device implements six state-of-the-art dynamically programmable logic arrays (PLA's) on a 2 mm x 2 mm die. The devices were fabricated through the Lucent Technologies-Advanced Research Projects Agency-Consortium for Optical and Optoelectronic Technologies in Computing (Lucent/ARPA/COOP) workshop by use of 0.5-mum complementary metal-oxide semiconductor-self-electro-optic device technology and were delivered in 1998. All devices are fully functional: The electronic data paths have been verified at 200 MHz, and optical tests are pending. The device has been programmed to implement a two-stage optical switching network with six 4 x 4 crossbar switches, which can realize more than 190 x 10(6) unique programmable input-output permutations. The same device scaled to a 2 cm x 2 cm substrate could support as many as 4000 optical I/O and 1 Tbit/s of optical I/O bandwidth and offer fully programmable digital functionality with approximately 110,000 programmable logic gates. The proposed optoelectronic FPLD is also ideally suited to realizing dense, statically reconfigurable crossbar switches. We describe an attractive application area for such devices: a rearrangeable three-stage optical switch for a wide-area-network backbone, switching 1000 traffic streams at the OC-48 data rate and supporting several terabits of traffic.     

Josephson quantum interference computer devices

Josephson devices are potential elements for ultra-fast computers. Rather complex logic and memory circuits have been realized. Here quantum interference devices with improved speed and power performance are discussed. Latching and non-latching logic operation is possible and experiments with non-latching circuits are reviewed. Memory applications of quantum interference devices are also considered.     

Integrated all-optical logic and arithmetic operations with the help of a TOAD-based interferometer device--alternative approach

Interferometric devices have drawn a great interest in all-optical signal processing for their high-speed photonic activity. The nonlinear optical loop mirror provides a major support to optical switching based all-optical logic and algebraic operations. The gate based on the terahertz optical asymmetric demultiplexer (TOAD) has added new momentum in this field. Optical tree architecture (OTA) plays a significant role in the optical interconnecting network. We have tried to exploit the advantages of both OTA- and TOAD-based switches. We have proposed a TOAD-based tree architecture, a new and alternative scheme, for integrated all-optical logic and arithmetic operations.     

Visual-area coding technique (VACT): optical parallel implementation of fuzzy logic and its visualization with the digital-halftoning process

A novel technique, the visual-area coding technique (VACT), for the optical implementation of fuzzy logic with the capability of visualization of the results is presented. This technique is based on the microfont method and is considered to be an instance of digitized analog optical computing. Huge amounts of data an be processed in fuzzy logic with the VACT. In addition, real-time visualization of the processed result can be accomplished.