Abstract
All-optical modulation format conversion plays an important role in the future optical communication networks due to the different modulation formats are selectively applied to various optical networks. In this dissertation, we focus on the topic of modulation format conversion. To decrease the capital costs and network complexity for the further all-optical communication networks, we committed to develop a simple, cost-effective and lower-complexity modulation format converter. We start from modulation format conversion from several low-speed signals to a high-speed one, including all-optical 20Gbps QPSK and 10Gbps ASK to a 30Gbps QPSK signal by using FWM mechanism; XPM-based all-optical 4 12.5Gbps NRZ-OOK signals to a 50Gbps PDM RZ-QPSK signal with a simple and cost-effectively methods. On the other hands, we keep to investigate the modulation format conversion from a high-speed signal to several low-speed signals. We propose and experimental demonstrated a all-optical phase-transparent format conversion from a 25Gbps QPSK signal to 2 × 12.5Gbps BPSK signals by using FWM nonlinearity in a double-pass scheme. Furthermore, we propose a multifunctional all-optical format converter based on four-wave mixing in a bi-directional architecture. Multi-functions, including: high-speed to low-speed and low-speed to high-speed format conversions are simultaneously demonstrated both in simulation and experiment. Based on the simple structure, the proposed format converter has great potential to decrease the implement costs and network complexity. Besides, the annoying back-propagating effect, including Rayleigh back-scattering (RBS) and stimulated Brillouin scattering (SBS) can be avoided to affect the other function. In the scenarios of phase de-multiplexing, the converted signals can preserve the phase information of the original signal by adapting two optical pumps. On the other hands, the function of phase multiplexing is also achieved without any additional pumps, which can offers great spectrum efficiency.