Optimization Of Optical Filtering In High Speed All-Optical Wavelength Conversion

All-optical wavelength converters (AOWC), which play an important role in constructing flexible all-optical networks and fully utilizing the limit resource of wavelength, will become essential devices in the auto switch optical networks (ASON) by wavelength switching. Owing to its high nonlinear effects, low cost, pumped by electric current directly and integrated easily, semiconductor optical amplifier (SOA) becomes the most important component in high-speed optical signal processing. The technique to realize AOWC based on SOA is mature under 40Gb/s bitrates. However, for the higher bitrates, the relative long carrier recovery time of SOA limits the speed of wavelength conversion. Recently, the schemes of cascading SOA and optical filters have been reported to realize high speed wavelength conversion. In order to make it clear how the optical filters operate to diminish the impact of slow recovery of SOA, theoretical researches on all-optical wavelength converters based on cascading SOA and optical filters are presented assisted by simulation. Then this thesis focuses on the optimization of optical filtering to improve the output performance of wavelength conversion. The main contents are listed as follows:(1) The research background and achievements of high speed all-optical wavelength converters based on cascading SOA and optical filters are clarified.(2) High-speed nonlinearities of SOA and ultrafast nonlinearities of SOA are clarified. By introducing carrier heating and spectral hole burning, SOA ultrafast dynamic model for ultrafast pulses is presented. The phenomenon of slow carrier recovery and the theory of linear and nonlinear patterning are analyzed.(3) The model of cascading SOA and narrow bandpass filter is set up. Assisted by simulation, the theory to realize high speed inverted or non-inverted wavelength conversion is analyzed, and the structural parameters of narrow bandpass filter are optimized.(4) The model of cascading SOA, an AMZI and a narrow bandpass filter is set up. Assisted by simulation, the theory to realize high speed non-inverted wavelength conversion is analyzed, and the structural parameters of NBPF and AMZI are optimized. In addition, the multiple wavelength converter based on the cascading SOA and an AMZI is introduced.