Micro and Nanosystems  Kajal Maji 1 and Kousik Mukherjee 1,* 1 Department of Physics, B.B. College, Asansol, India Abstract: Background: In this paper we have design and analyzed 4-bit binary to 4-bit gray code and 4-bit gray to 4-bit gray code converter using dual control dual semiconductor optical amplifier te- rahertz optical asymmetric demultiplexer (DCDS-TOAD). We used control pulse as a Soliton pulse train. We calculate the extinction ratio, contrast ratio and Q value and found very high values. The high values of E.R., C.R. and Q value distinguishes the high (‘1’) level to the low(‘0’) very clearly al- so shown the variation of E.R., C.R. and Q value with control pulse energy and amplified spontaneous emission power factor. Methods: The basic equations governing the TOAD performance is simulated using MATLAB. The extinction ratio, contrast ratio and Q value are calculated for analysis of the device. Results: Results of operation for the code converters are performed at a bit rate of 100Gbps. The structure of DCDSTOAD enable us to achieve high values of ER(~ 81dB), CR(~83dB) and Q factor (86dB). A high Q factor shows very low bit error rate (BER). The eye diagram shows a large eye opening (REOP~98.5%). Conclusions: Design and analyzed 4-bit binary to 4-bit gray code and 4-bit gray to 4-bit gray code converter using dual control dual semiconductor optical amplifier terahertz optical asymmetric demul- tiplexer (DCDS-TOAD) is proposed and analyzed. We used control pulse as a Soliton pulse train. The proposed X-OR gate finds applications in many devices. A R T I C L E H I S T O R Y Received: May 08, 2019 Revised: September 17, 2019 Accepted: November 29, 2019 DOI: 10.2174/1876402912666200123105631 Keywords: Optical logic, binary code, gray code, DCDS-TOAD, gain saturation, Q value, ASE noise. 1. INTRODUCTION In the last few years, Semiconductor Optical Amplifier (SOA) based switching became popular among researchers in optical computation and signal processing as an alterna- tive technique again [1-6]. Due to this trend in the last few years, several combinational and sequential logic devices have used various SOA based switching mechanisms such as four-wave mixing, non-linear polarization rotation, cross gain modulation, etc. [1-9] for their implementation. X-OR gate is an important logic gate and is used in many applica- tions in computation and communication systems [8, 9]. TOAD based optical switching based on SOA is an efficient candidate due to its low switching energy, high speed, rea- sonable noise power, ease of integration, etc. [4]. Many TOAD based logic gates use single SOA in the fiber loop structure [1-5, 7, 10]. In this communication, we analyzed double SOA based TOAD or Dual Control Dual SOA TOAD (DCDSTOAD) and its switching performance is ana- lyzed by calculating gain and output powers and pseudo eye diagram of the proposed X-OR gate (controlled NOT gate). Gray code has importance for the communication system because it minimizes adjacent decision bit errors [11]. *Address correspondence to this author at the Department of Physics, B.B. College, P.O. Box: 713303, Asansol, India; Tel/Fax: +91 9434122481; E-mail: klmukherjee003@gmail.com Recently, all-optical binary to Gray code converter and Gray to binary code converter have been proposed using Reflective Semiconductor Optical Amplifier [12], Mach Zhender Interferometer [13, 14], Microring resonator [15], Sagnac Switch [16], TOAD [17], etc. In our previous work, we utilized DCDSTOAD to design the NOR gate [18]. In this communication, the proposed DCDSTOAD based X-OR gate [19] is utilized to design four-bit binary to Gray code and Gray to Binary code converter for the first time as far as our knowledge goes. The performance of these devices is analyzed in terms of the eye diagram, Extinction Ratio (ER), Contrast Ratio (CR), and Quality factor (Q), and soliton pulses as control also result in output as soliton pulses, which are important in long-distance communication sys- tems. This DCDSTOAD based switch can be useful in de- signing future complex logic processors and networks. 2. METHOD: THEORETICAL MODELING The basic building block of these code converters is the XOR gate which consists of a loop mirror. The loop mirror consists of two identical SOAs (both having offset from the loop midpoint by an amount Δ) biased with the same current, two SOAs use two different control signal input points (A and B), a 2x2 coupler, a circulator, and filters at data signal input port and output port. The output signals switch be- tween port-1 and port-2 by the control signals. The coupler 1876-4037/20 $65.00+.00 ©2020 Bentham Science Publishers Send Orders for Reprints to reprints@benthamscience.net Micro and Nanosystems, 2020, 12, 175-186 175 RESEARCH ARTICLE Design and Analysis of X-OR Gate and 4-Bit Binary to 4-Bit Gray and Gray to Binary Code Converter Using Dual Control Dual SOA TOAD (DCDS-TOAD)