All-optical Wavelength Converter Based On FWM In Semi-conductor Optical Amplifier With Dual-pump For PolSK Format

All-optical wavelength converters can make the wavelength division multiplexing (WDM) system to eliminate the wavelength competition and have a flexible and reliable network. All-optical wavelength converters will become important optoelectronic devices in automatically switched optical networks (ASON) and play a key role with the development of all-optical networks. There are a lot of schemes to implement all-optical wavelength converters, the converters which based on four-wave mixing (FWM) in semiconductor optical amplifiers (SOA) have received widespread attention due to their advantages including transparency to the modulation format and bit rate of the input signal. At present, many researches about all-optical wavelength converters only based on the signal modulation formats of binary amplitude shift keying (OOK) and differential phase shift keying (DPSK), but it is very few to the signal modulation format of polarization shift keying (PolSK). Based on dual-pump FWM effect in SOA, this paper proposed a scheme of all optical wavelength conversion for PolSK. This wavelength conversion scheme has the advantages of high conversion efficiency, high extinction ratio and big range of wavelength conversion. We studied this all-optical wavelength converter based on dual-pump FWM effect in SOA for the signal modulation format of PolSK. The main contents are listed as follows:1) The significance of investigation on all-optical wavelength converters is described. The development of all kinds of all-optical wavelength converters is outlined.2) The nonlinearities of SOA are discussed, especially the third-order nonlinearities. The propagation equation for the optical field and the rate equation for the carrier density in SOA are derived.3) This paper used dual-pump FWM effect in a SOA, proposed a scheme of all optical wavelength conversion for PolSK. This scheme can improve the conversion efficiency,extinction ratio and range of wavelength conversion.4) The comprehensive broad-band dynamic model of wavelength conversion based on FWM in a SOA is presented firstly. In the broad-band dynamic model, the material gain profile, the longitudinal variation of the optical field, the carrier density, photon density, and the broad-band spontaneous noise emission are considered in the model. This broad-band dynamic model is the theoretical basis to study the wavelength converter based on FWM in a SOA.5) Using the broad-band dynamic model of wavelength converter based on FWM in a SOA, the conversion efficiency and the extinction ratio are investigated by numerical simulation with MATLAB, the effects of the input pump powers, signal powers, input pump wavelengths and signal wavelengths on the conversion efficiency and extinction ratio are analyzed.