1 All-optical Reversible Logic Gate implementation using TOAD Sandip Mandal 1 , Supriti Samanta 2 , Goutam Kumar Maity 3 , Subhadipta Mukhopadhyay 4 1 Dept. of computer science, Raja Narendralal Khan Women's college, Midnapore, India 2 Department of Physics, Chaipat Girls‘ High School, Paschim Medinipur, India 3 Dept. of Eectronics and Communication Engineering, Netaji Subhash Engineering College, Kolkata, India 4 Department of Physics, Jadavpur University, Kolkata, India ABSTRACT Reversible logic is emerged as a promising computing paradigm with applications in low-power CMOS, quantum computing, optical computing and nanotechnology. Optical logic gates become potential component to work at macroscopic (light pulses carry information), or quantum (single photon carries information) levels with high efficiency. In this paper, we propose a novel scheme of Fredkin and Peres gates realization in all-optical domain. Simulation results verify the functionality of both the gates as well as reversibility. Approximate insertion power loss in dB is also reported for the Gaussian incident and control pulse. 1. Introduction All-optical switching - the switching of one beam of light by another — is an essential operation for transparent fiber optic networks and for all forms of optical information processing [1-6]. In order to overcome the electronic bottlenecks and fully exploit the advantages of optical fiber communication, it is necessary to move towards networks where the transmitted data would remain exclusively in the optical domain without optical-electrical-optical (OEO) conversions [7]. Two fold driving forces for this all-optical switching are the broadband photonic network environment that emerges due to rapid convergence of telecommunication and informatics. The other one is the massive use of data applications such as internet and multimedia. All-optical gates avoid complex and speed-limited optoelectronic conversions. Among the proposed schemes, the terahertz optical asymmetric demultiplexer (TOAD) and semiconductor optical amplifier (SOA)-assisted Sagnac gate effectively offers fast switching time and a reasonable noise figure [8]. Moreover ease of integration and overall practicality enable it to compete with other similar optical time division multiplexing (OTDM) devices [9]. In conventional computers, majority of the computation operations are irreversible i.e. once a logic block generates the output bits based on certain input combinations, the later bits are lost. The classical set of gates such as AND, OR and X-OR are irreversible as they are all multiple-input single output logic gates. However, this is not the case for reversible logic circuits. A gate is reversible if the gate’s inputs and outputs have a one-to-one correspondence, i.e. there is a distinct output assignment for each distinct input combination. Therefore, a reversible gate’s inputs can be uniquely determined from its outputs. Keywords: Reversible logic gates, Fredkin Gate (FG), Peres Gate (PG), Terahertz Optical Asymmetric Demultiplexer (TOAD). International Journal of Computer Science and Information Security (IJCSIS), Vol. 14, No. 12, December 2016 664 https://sites.google.com/site/ijcsis/ ISSN 1947-5500