A Method to Implement Data Extraction Using and Optical Gate Based on Soa - Nolm

Abstract

A method was proposed to implement data extraction using AND optical gate operation on semiconductor optical amplifier (SOA) based nonlinear optical loop mirror (NOLM). The optical data extraction in FSK/ASK orthogonal modulation system was achieved with the proposed AND gates, in order to prove its feasibility. Through the simulation, the data extraction in orthogonal modulation system with a 10Gbit/s NRZ pseudo-random payload signal and 2.5Gbit/s label signal was demonstrated. Index Terms - Optical label, optical logic gate, orthogonal modulation, semiconductor optical amplifier. I. Introduction Optical swapping and optical computing are the core unit to achieve all optical signals processing in future all optical networks, they all based on optical logic gates, which are core devices to implement optical swapping system and the key factor of decision network performance. All optical logic gates(XOR、AND)are indispensable part for all optical signal processing,which can be used in all-optical clock recovery, all- optical demultiplexing, all-optical data extraction, etc. Therefore, it has great application potential in future all optical high speed communication network and new generation optical computing. At present, the research of all optical logic gates are focused on the using of nonlinear effect of optical fiber and semiconductor optical amplifier. The nonlinear effect of optical fiber is weak, so that the logic gates based on nonlinear effect of optical fiber will achieve idea effect only by high power input signal or long fiber. SOA become the main functional device to implement all kinds of optical logic gates, because it has many advantages such as small in size, easy to integrate, short response time and strong nonlinear effect. Taking the nonlinear effect advantage of SOA can realize many kinds of optical logic gates, but the design scheme to realize AND gate is relatively less, for example, using two- level SOA's cross gain modulation effect implementing AND gate, using Mach-Zehnder interferometer based on SOA implementing AND gate, etc. optical data extraction is an important part in optical label swapping system, it is the key factor for all optical network. At present, there have been many design and experiment scheme about optical data extraction. These schemes have it own advantages, but they also have some disadvantages. Article (1) realized all optical data extraction by using start bit in data packet generating address. This method has the advantage of easy to realize and doesn't need complicated clock recovery module; but the realization of control pulse division module is closely related to the length of the packet address, it is needed to increase or decrease the same number of delay fiber when the length of address is increased or decreased. Article (2) realize data extraction from packet through the switch module which are consisted of Mach-Zehnder interferometer based on two-level SOA and Fabry-Perot filter, clock recovery module and address-data separation module; this scheme has the advantage of high speed and flexible; but configuration structure is too complex. By contrast, the method to implement data extraction using AND optical gate has the advantage of high speed in data extraction, simple structure and easy to integrate. In this article we put forward a method to implement AND optical gate using two SOAs based NOLM structure, and in order to prove the AND gate having the ability in information processing, the AND gate is applied to load FSK/ label ASK orthogonal modulation system to extract data information. Through the simulation, the data extraction in orthogonal modulation system with a 10Gbit/s NRZ pseudo-random payload signal and 2.5Gbit/s label signal is demonstrated.