Theoretical And Experimental Study On All-optical Wavelength Converter Based On Single-port Coupled SOA

All-optical wavelength converters (AOWC) will become essential devices in the auto switch optical networks (ASON) by wavelength switching. In the schemes of most all-optical wavelength converters, the wavelength converters based on cross gain modulation (XGM) in semiconductor optical amplifier (SOA) is one of the most mature and promising ones, which have obvious advantages, such as simple implementation, high conversion efficiency and large wavelength conversion span. But it also has some disadvantages to prevent its practical applications. For example, the output extinction ratio degeneration is very serious, especially up-conversion. In order to promote the extinction ratio and maintain the other advantages, a novel scheme for XGM wavelength conversion based on single-port-coupled (SPC) SOA is proposed in this dissertation, supported by Hi-Tech Research and Development Program of China (Grant No. 863-2002AA312160) and Sci&Tech Breakthrough about Optical Communication of Wuhan (Grant No. 2002100513013). We focus on wavelength conversion based on single-port coupled SOA, several theoretical and experimental studies have been carried out as the following: (1) The research signification of all-optical wavelength converters is analyzed. The schemes of the all-optical wavelength converters are summarized. (2) The theoretical models of wavelength converters based on single-port coupled SOA are established. First, several static numerical models are analyzed, which include a simple one and a complex one. The simple one neglects the amplified spontaneous (ASE) noise and reflectivity of SOA fore facet, but the complex one takes the ASE and the facets of SOA into account. Then a dynamic model base on single-port coupled SOA is established. At last the dynamic gain model of SOA is analytically deduced. The establishment of the models is the foundation to optimize the parameters of SOA. (3) The output properties of wavelength converters based on single-port coupled SOA, such as extinction ratio, chirp, conversion efficiency and gain recovery time, are theoretically analyzed according to the models of chapter 2. The output properties are analyzed with variations of averaged pump power, probe power, wavelength conversion span, bias current of SOA, rear facet of SOA and active region length. The performances of single-port coupled SOA and traditional SOA are compared and the result shows that the former is better if the parameters are optimized. (4) The output properties of wavelength converters based on single-port coupled SOA are experimentally studied. First, the performances of single-port coupled SOA are measured. Then the processes of wavelength conversion at 10Gb/s and 20Gb/s are validated respectively. And then, the output properties at 10Gb/s in different conditions are mainly discussed. The experimental results prove the theoretical simulations of chapter 3. Under the condition of 20Gb/s, the causation of pattern effect is analyzed in the process of wavelength conversion. The experiments that converted signal is transmitted in single mode fiber of 100km are also carried through at both 10Gb/s and 20Gb/s. The transmission characters of converted signal are analyzed.