Research On Key Enabling Techniques And Experimental Systems For Ultra-High Speed Optical Transmission

To meet the ever-increasing bandwidth demand, the following thesis con-cerns ultra-high speed optical communication systems and optical signal pro-cessing techniques aiming at large capacity and high spectral efficiency.For optical signal processing techniques, an analogue coherent receiver based on heterodyne detection and an electrical delay interferometer was pro-posed and realized, achieving a sensitivity of-45.18dBm for2.5Gbaud DPSK signal. All-optical XOR gates for QPSK modulated signals were also proposed and experimentally implemented at40Gbaud by four-wave mixing in a semi-conductor optical amplifier.For large capacity transmission, the main focus is on optical time-division multiplexing (OTDM) systems in this thesis. A demultiplexed-feedback clock recovery scheme was proposed. The relationship between the strength of the base rate clock and the distribution of the OTDM tributaries was theoretically analysed. The scheme was experimentally verified in a dual-polarization, QPSK modulated640Gbit/s-400km OTDM system.31fs timing-jitter under back-to-back scenario and35fs timing-jitter after transmission of the40GHz recov-ered clock were achieved, enabling error-free performance of the whole OTDM system. For high spectral efficient transmission, the thesis mainly focuses on orthogonal (Nyquist) optical time-division multiplexing (Nyquist-OTDM) sys-tems. Through international collaboration, a DPSK modulated dual-polarization1.28Tbaud (2.56Tbit/s)-100km Nyquist-OTDM transmission system was ex-perimentally implemented and investigated. Utilizing time-to-frequency con-version based on time-domain Fourier Transformation (TD-OFT) as the demul-tiplexing scheme, error-free performance of the system was achieved with the aid of a hardware forward error-correction (FEC) module. Furthermore, the thesis proposed an all-optical orthogonal frequency-division multiplexed (AO-OFDM) transceiver based on TD-OFT and frequency-domain optical Fourier transformation (FD-OFT), which was further verified and investigated through international collaboration in a16subcarriers, DPSK modulated160Gbaud-100km proof-of-concept transmission experiment.