Theoretical Research On All Optical Modulation Format Conversion Based On Soa

All optical signal processing is one of the promising technologies in future all optical networks.Recently, all optical format conversion has received much interest. It becomes a key technology to interconnect future optical networks, which could employ different modulation formats according to the network scales and applications. Semiconductor optical amplifier (SOA) is very fit for all optical modulation format conversion due to its high nonlinear characteristics, lower switch power and small size.In this thesis, we first introduced some kinds of optical modulation formats. Then, we discussed the features of the SOA, which is the core components of the all optical format conversion, and established a theoretical model which accurately described SOA. Finally, we focus on two schemes of format conversions based on SOA as follows.1. Modulation format conversions between non-return-to-zero(NRZ)and return-to-zero(RZ)We used the proposed scheme of all optical molulation format conversion, which is constituted by SOA and optical band pass filter(OBPF). Through the research on the change of the carrier density caused by input control signal, the change of the phase and the frequency chirp of the probe light, we analyzed the impact to converted signal due to the detuning of the OBPF. The numerical simulation is given with the transmission rate at 40Gbit/s.2. Modulation format conversion from return-to-zero-on-off-keying (RZ-OOK) to return-to-zero-binary-phase-shift-keying (RZ-BPSK) and DuobinaryWe proposed a scheme of all optical format conversion,which is based on SOA-Mach-Zehnder(MZI) structure and constituted by a single SOA and the fiber delay line. Through adjusting the input signal power and controlling temperature, the numerical simulation results of format conversion from RZ-OOK to RZ-BPSK and Duobinary was given with the transmission rate at 40Gbit/s.