Simulation of All Optical Time Division Multiplexed Router Ruixin Gao* a , Zabih Ghassemlooy a , Graham Swift a and Peter Ball b a Optical Communications Research Group, Sheffield Hallam University, S1 1WB,U.K. Fujitsu Europe Telecom R & D Centre Ltd, UB11 1AB. U.K. ABSTRACT To date most research on optical networking has concentrated on wavelength-division multiplexing (WDM), which routes different packets according to the wavelength of the optical carrier. Optical time-division multiplexing (OTDM) is considered as an alternative to WDM for future networks and with single stream data rates of 100 Gb/s using a single wavelength at high (up to 100 Gbit/s) data rates 1-3 . In this paper we have developed a model of an all optical router based on the terahertz optical asymmetric demultiplexer (TOAD). The model architecture is based on a system which has as its input an OTDM packet containing header and payload information. The model simulates extraction of header information from the data stream using one TOAD, which is subsequently used to make a routing decision. The payload information is routed through a second TOAD according to the information contained in the header. Simulations require the use of the TOAD in two distinct modes 1). A bit level demultiplexer for the header 2). A frame level demultiplexer for the payload. Consequently less stringent requirements are required with regard to the TOAD switch resolution for payload demultiplexing compared to header demultiplexing. However, as our simulations show the wider window allowed in case 1 introduces a higher level of residual crosstalk. In case 2 the higher resolution imposes a greater restriction on the jitter present. At this stage a simple 1 by 2 router is presented, however further work will enhance the model to a network with multiple inputs and outputs. Keywords: Communication system, Optical switches, Routing, Demultiplexing, Optical Time division multiplexing (OTDM), Terahertz optical asymmetric demultiplexer (TOAD), Optical signal processing. 1. INTRODUCTION OF ALL OPTICAL ROUTER 1.1 Introduction to TOAD The model presented in this paper is composed of two terahertz optical asymmetric demultiplexers (TOAD) 1 . The single TOAD architecture is shown in Fig.1, which is composed of a small optical loop mirror, a nonlinear element (a semiconductor optical amplifier SOA) and an intraloop 2X2 coupler for injecting control (clock) pulses into the SOA. When OTDM data pulse enters the TOAD, each pulse splits into equal clockwise (CW) and counterclockwise (CCW) components. They counter-propagate around the loop and arrive at the SOA at slightly different times as determined by the offset ∆x of the SOA from the midpoint of the loop. When control pulse arrives at the SOA just before the CCW component, but just after its CW counter propagating complement, it induces non-linearities in the SOA which cause the two components to experience different gains and phase shifts, consequently recombine and exit the loop at the output port 2. All other data are reflected by the loop mirror and exit the loop via port 1 in the absence of a control signal. ----------------------- *Correspondence: Email:r.gao@shu.ac.uk; WWW:http://www.shu.ac.uk/ocr; Telephone:0044 –114-2253254; Fax:0044-114-2253433