All-optical half-adder/half-subtractor using terahertz optical asymmetric demultiplexer

Abstract

Logic gates are the fundamental building blocks of digital systems. Using these logic gates, one can perform different logic and arithmetic operations. All-optical logic and arithmetic operations are very much expected in high-speed communication systems. In this paper, we present a model to perform addition/subtraction operations on two binary digits based on a terahertz optical asymmetric demultiplexer (TOAD). Using four TOAD-based switches, we have designed a half-adder and half-subtractor circuit. The approach to designing all-optical arithmetic circuits not only enhances the computational speed but is also capable of synthesizing light as inputs to produce the desired outputs. The main advantages of this circuit are that synchronization between inputs is eliminated and simultaneous addition and subtraction operations are realized at the outputs. This circuit is designed theoretically and verified through numerical simulations. The impact of the control pulse energy, gain recovery time, and the input data pulse width on the extinction ratio, contrast ratio, amplitude modulation, Q-factor, and relative opening of the pseudo-eye diagram of the switching outcome is explored and assessed by means of numerical simulations.

Ultracompact all-optical full-adder and half-adder based on nonlinear plasmonic nanocavities

“…The practical on-chip integration applications require several key indexes for these nanoscale all-optical logic devices: ultrasmall feature size, ultralow threshold power, ultrahigh contrast ratio, as well as on-chip trigger [2,3]. More often than not, highly nonlinear fibers [4][5][6], optical asymmetric demultiplexers [7,8], and bulk periodically poled lithium niobate crystals [9][10][11] are used to demonstrate all-optical logic functions. The large size of the bulk materials and lumped components, having a feature size of several centimeters, limits the practical on-chip integration applications [12,13].…”

Simultaneous all-optical basic arithmetic operations using QD-SOA-assisted Mach–Zehnder interferometer

“…An all-optical half adder using two MZI switches [13] and one MZI switch [14] has been proposed in our previous contribution. Also, we proposed four terahertz optical asymmetric demultiplexer (TOAD)-based adder subtractor circuits [15]. TOAD is a one-arm interferometer.…”

“…The all-optical QD-SOA-based switches and different operations have been studied by different research groups [16][17][18][19][20][21][22]. In our previous paper [15], we have used four TOAD-based optical switches, but in this paper, we have proposed and describe a simultaneous all-optical half adder/subtractor circuit using only two QDSOA-MZI-based all-optical switches. The overall performance of the current circuit is better than the previous one.…”

“…In our previous circuit, the operation speed was limited to 20 Gb/s which was less than the current circuit (160 Gb/s). In our previous work [15], we used TOAD-based switches in which conventional SOAs act as a nonlinear element, but here quantum dot SOAs (QD-SOAs) act as the nonlinear element. The technology of QD-SOAs is very suitable due to their ultra-fast response, which, combined with its attractive characteristics, distinguishes them from conventional SOAs.…”

Performance Analysis of a High-Speed All-Optical Subtractor using a Quantum-Dot Semiconductor Optical Amplifier-Based Mach-Zehnder Interferometer

“…Subtraction is one of the most important operations in Boolean functions and is used in binary subtraction, binary counting, arithmetic logic units, encryption, and decryption in security networks. Many designs for a single subtractor or subtractor with adder have been proposed by using a semiconductor optical amplifier (SOA) and periodically-poled lithium niobate (PPLN) waveguide [4], micro-ring resonator [5], exploiting four-wave mixing (FWM) in a SOA [6], a SOA based-Mach-Zehnder interferometer (MZI) [7], a three-state system [8], a terahertz optical asymmetric demultiplexer (TOAD) [9], a single-slot waveguide [10], two SOAs [11], implementing nonlinear material [12], and a nonlinear directional coupler [13]. SOA with quantum-dot active region is a promising candidate for ultrafast operations [14][15].…”