All-optical Adder Research Articles

A review on all-optical logic adder: Heading towards next-generation processor

In this paper few literatures on all-optical adders, reported approximately in last fifteen years, have been reviewed. Being the key element of arithmetic and logic unit (ALU), adder has attracted stirring attention of the researchers. The reviewed articles are primarily categorized into three broad sections based on the platforms utilized in designing all-optical adder namely semiconductor optical amplifier (SOA), plasmonics and photonic crystal (PhC). SOA based designs offer high contrast ratio between the output logic levels, however; at the cost of high response time and operating power. Plasmonic based designs provide miniaturized physical footprint of the devices owing to the tight optical confinement. Nevertheless, the process of fabrication involved with the plasmonic based designs along with the loss incurred at the metal are among the limiting features. In contrast, PhC based designs are much more advantageous owing to the notable characteristics of light propagation. The operating power and bandwidth of operation are also higher as compared to the other designs. Photonic crystal-based designs are further categorized into linear and nonlinear domains based on their operating principle. The design structures and performances have been summarized and a comparison is made. Some insights have been discussed leading to design of more efficient PhC based all-optical adders for next generation ultra-first optical processors.

Improved Designs for All-Optical Adder Circuit Using Mach–Zehnder Interferometers (MZI) Based Optical Components

Since last decade, optical computing has emerged as one of the promising computing paradigm in the field of ultra-fast computations and the recent advancements of fabrication technology in photonic industry has further boosted research interests to investigate in this field. In this conjuncture, strategies for designing efficient optical circuits bear much significance toward building cost efficient logic circuits. Not only synthesis schemes but manual designs for logic components are found very effective in way to produce optimal designs. In this work, we present the optical domain designs of an important logic module of ALU—adder circuit. Not only we have made the adder circuit optical domain supporting one but also we have ensured that the designs are optimized too. Here we have worked with two types of adder circuits Carry-Lookahead Adder and Carry-Skip Adder. All the designs are made using Mach–Zehnder interferometers based optical components and interconnect. For both the adder types, two different designs are shown and in each of these designs both the circuit cost parameters and response time is improved. Design overhead and hardware complexities for all the circuits are computed and have compared with related work’s design, where we have found that our designs are having less delay and cost efficient compared to the existing ones.

All-optical polarization-encoded negabinary signed-digit adder designs using terahertz-optical-asymmetric-demultiplexer switches

Incontrast to intensity-encoded negabinary modified signed-digit number representation, a polarization-encoding scheme is proposed to design all-optical adders. The utilization of the proposed polarization-encoding produces more efficient circuits in terms of gates numbers and circuit delays. Three all-optical adder circuits are designed using Terahertz-Optical-Asymmetric-Demultiplexer (TOAD) switches,polarization beam splitters, polarization converters, and beam combiners. Itwill be shown that the proposed circuits utilize 51.7%, 45.5%, and 21% less gates and they are faster by 44.4%, 42.9%, and 40%, respectively, than thecorresponding intensity-encoded circuits.

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.

All-optical negabinary adders using Mach–Zehnder interferometer

In contrast to optoelectronics, all-optical adders are proposed where all-optical signals are used to represent the input numbers and the control signals. In addition, the all-optical adders use the negabinary modified signed-digit number representation (an extension of the negabinary number system) to represent the input digits. Further, the ultra-speed of the designed circuits is achieved due to the use of ultra-fast all-optical switching property of the semiconductor optical amplifier and Mach–Zehnder interferometer (SOA–MZI). Furthermore, two-bit per digit binary encoding scheme is employed to represent the trinary values of the negabinary modified signed-digits.

All-Optical Incrementer/Decrementer with the Help of Semiconductor Optical Amplifier-Assisted Sagnac Switch

In this article, an all-optical adder based incrementer/decrementer circuit is proposed and described with the help of Semiconductor Optical Amplifier (SOA)-assisted Sagnac switch. The proposed design is more efficient in terms of speed and hardware complexity. The article describes the incrementer/decrementers using a set of optical half adder and full adder. The principle and possibilities of all-optical incrementer/decrementers is explained. A theoretical model is presented and verified through numerical simulation. The new method promises both higher processing speed and accuracy. The model can be extended for studying more complex all-optical circuit of enhanced functionality in which incrementer/decrementers is the basic building block.

Single SOA based all-optical adder assisted by optical bandpass filter: Theoretical analysis and performance optimization

A simple and compact configuration of all-optical adders implemented with a single semiconductor optical amplifier (SOA) and optical bandpass filter (OBF) is presented in this paper. A comprehensive SOA model is put forward to investigate the output characteristics of the all-optical adders. The numerical simulation results demonstrate the influence of these key parameters, including input pulse peak power, pulsewidth, repetition rate, and OBF characteristics. Moreover some design rules are extracted for the proper selection of these parameters so as to ensure optimum performance. The obtained results confirm the feasibility of our configuration.

All-optical signal processing in photonic structures with nonlinearity

A principal scheme for an all-optical adder based on the dependence of electromagnetic spectra in photonic bandgap materials containing optically nonlinear layers on the light signal intensity is proposed. The photonic structure behavior with changing intensity is investigated for a system consisting of a periodically layered structure covered with optically nonlinear material. Theoretical estimations of adder cell parameters are made for Si/SiO2 photonic crystals covered with layers made from nonlinear materials. Furthermore, the adder design is discussed.