All-optical signal processing and conditioning in high-speed optical systems using semiconductor optical amplifiers.

摘要

The semiconductor optical amplifier (SOA) has recently attracted much interest for wide applications in high-speed optical communication systems, owing to its large gain bandwidth, compactness, and potentially low cost. It can serve as in-line amplifier and power booster for optical amplification. In future optical packet./circuit switching networks, to overcome the electronic bottleneck in switching and routing, large switching matrices implemented by SOA gates have been widely considered and investigated for its fast response (∼1ns) and excellent on/off extinction ratio. Moreover, because of the nonlinear characteristics of SOA, it can be also used for ultrahigh speed optical signal processing, including wavelength conversion, all-optical time division demultiplexing and optical logic gates.; However, when the SOA is operated in saturation regime, its fast gain dynamics causes patterning dependent distortion, in such a way that the amplifier gain greatly varies with the waveform of the input signal. The amplified signal waveform suffers from severe distortion and thus greatly hinders the deployment of SOA in real-life systems. In this thesis, effective techniques have been developed to suppress the patterning induced degradation for different applications of SOA. When SOA is used as an amplification/on-off gating device, patterning induced degradation has been kept minimal by employing interferometric and polarimetric approaches. The input power dynamic range at same time has been largely enhanced. Besides, when the SOA is used for ultrafast all-optical signal processing, constant intensity modulation format, return-to-zero differential phase shifted keying (RZ-DPSK) has been proposed for all-optical time division demultiplexing and all-optical Exclusive-OR logic function operation. The proposed scheme has been successfully demonstrated and thus proved their effectiveness. Enhanced input power dynamic range with extended signal bit rate has been achieved.; In addition, an effective all-optical technique has been also proposed for high speed optical packet serial header/label processing by means of serial-to-parallel conversion. Thus, a parallel header bit sequence, each at a lower bit rate, can be obtained, which allows relaxed speed requirement for electronic processing.