Abstract

Semiconductor optical amplifier (SOA) devices are believed to play a major role in future all-optical networks. Here we consider a SOA based double-stage wavelength converter working with an assist light. Its sketch is pictured in figure 1. The principle of operation consists of injecting the pump (pulse data) and the assist light (CW at SOAs gain transparency) simultaneously in all amplifiers, while the CW probe crosses in series the amplifiers. In this way, the extinction ratios of the converted signal (e.g. the probe) are multiplied. The use of an assist light at gain transparency is well known to shorten SOA gain recovery time [1]. The attenuation A is adjusted in order to get the same injected probe power for both SOAs, e.g. -13 dBm here. In this work, we study the effects of probe and pump wavelengths on the achievement of a given extinction ratio on the probe signal. We use a model determining the time evolution of gain, carrier density and amplified spontaneous emission (ASE) in a SOA after propagation of a short pump pulse. It includes forward and backward ASE, pump, probe and assist light propagation [2]. Here, both SOAs are identical. The amplifiers length is 500 μm, it is a rectangular guide of 0.5x0.4 μm² and the injected current is 150 mA. The peak gain wavelength value is 1.54 μm. The injected assist light power is 5 dBm. The injected pump pulse power is adjusted in order to get a 10 dB gain compression for the SOA double-stage wavelength converter in all simulations. The pump pulse duration is 2.1 ps.

© 2007 IEEE