All-Optical Modulation Format Conversion And XOR Logic Gate Based On SOA

In order to meet people’s growing demands of information, communication technology is developing towards the direction of larger transmission capacity, higher transmission rate and longer transmission distance, and the future of optical fiber communication technology is all-optical communication network. The signal in the all-optical network is running from port to port in the form of light, avoiding the O/E and E/O conversions. Nowadays, the Erbium-Doped optical fiber amplifier (EDFA) and the wavelength division multiplexing (WDM) technology have greatly improved the transmission distance and the transmission capacity of the optical communication network. However, the so-called "electronic bottleneck" in the switching nodes limits the switching rate of electrical signals. All-optical signal processing, which processes the signal directly in the optical domain by using the all kinds of nonlinear effects in the optical devices and prevents the "electronic bottleneck", is attracting extensive attentions.As a kind of semiconductor devices, semiconductor optical amplifier (SOA) has many advantages, such as high optical nonlinearity, compact size, capable of being integrated, low power consumption and fast response speed. All-optical signal processing using SOA has become a hot research recently. In this thesis, the system schemes of all-optical modulation format conversion and all-optical logic XOR gate based on the SOA-MZI structure were studied.First, according to the carrier density rate equation and the traveling wave transmission equation of SOA, we discussed the change of carrier density, gain saturation properties, cross-gain modulation effect (XGM) and cross-phase modulation effect (XPM) when single continuous probe wave and single pulse control wave were simultaneously injected into the SOA. Second, we proposed a novel all-optical modulation format conversion scheme from OOK to BPSK which is based on SOA-MZI structure. We can modulate the phase of the probe signals accurately and conveniently by adjusting the power of the input control signals which were injected two arms of SOA-MZI respectively. We simulated the proposed scheme at10Gbit/s and the simulation results show its feasibility. Last, we proposed a novel all-optical XOR logic gate scheme which is based on SOA-MZI structure between two BPSK signals. We simulated the proposed XOR logic gate, simulation results show the the power penalty of the receiver is very low, which indicates the good system performance of the XOR logic gate. The result is very important for future research in all-optical signal processing.