All Optical Signal Processing For Advancd Modulation Formats

With increasing demand of transmission capacity, advanced modulated formats, which offer better nonlinearity tolerance and high spectral efficiency, have been receiving increasing attention in recent years. The use of these phase modulated formats brings new research fields:how to do all optical processing on advanced modulated formats.Sponsored by National Natural Science Foundation of China, National High Technology Research and Development Program of China, the National Basic Research Program of China and Project of Huawei Technology, all optical processing of phase modulated formats, such as all optical 2R, all optical retiming, all optical format conversion between diferential phase shift keying (DPSK) are fully-and systemically investigated, using optical nonlinear device and passive optical filter. The main research achievements and contributions are summarized as followings:(1) The generation and characteristics of various modulation formats used in optical communications are investigated and compared, in time and frequency domain. The impairments of wavelength division multiplexing (WDM) networks are analyzed and discussed, which shows the main problem of the phase modulated formats.(2) A simple amplitude regeneration scheme for phase modulated signals, such as return-to-zero differential-phase-shift keying (RZ-DPSK) signal, based on quantum-well (QW)-semiconductor optical amplifier (SOA) is investigated systematically. By choosing the proper parameters, due to the low linewidth enhancement factor (a-factor), the amplitude fluctuations are suppressed while the phase information is preserved. The regeneration property of the bulk SOA with large linwidth enhancement factor and the potiential use in WDM system are also investigated.(3) All optical phase and amplitude regeneration scheme for phase modulated signal based on nonlinear fiber loop mirror configuration is investigated systematically. By using additional SOAs, for the first time, the regeneration processes for the situation with large amplitude noise and situation with large amplitude noise plus large phase noise have been investigated and the regeneration have achieved. And it is versatile to multichannel DPSK and Differential Quadrature Reference Phase Shift Keying (DQPSK) signals. The performance of regenerated signal is greatly improved. A significant improvement of eye opening and transmission length expansion can be observed for DPSK signal, multichannel DPSK signals and DQPSK signal, respectively.(4) The conversions from return-to-zero differential phase shift keying (RZ-DPSK) to non-return-to-zero DPSK (NRZ-DPSK) are investigated. By using a 0.5 bit time delay DI and lnm bandpass filter. Single channel format conversion scheme at 40Gbit/s is demonstrated. By using a 0.5 bit time delay DI and a 100GHz DI, or an array waveguide grating (AWG), multi-channel format conversion at both 20Gbit/s and 40Gbit/s are demonstrated.(5) A new kind of all optical format conversion from NRZ-D(Q)PSK to RZ-D(Q)PSK signal is proposed by using phase modulators and detuning filters. The optical spectra, temporal waveforms and eye diagrams are studied in detail to confirm the successful realization of NRZ-D(Q)PSK to RZ-D(Q)PSK format conversion. Furthermore, the same scheme may also be robust in RZ-D(Q)PSK retiming with WDM practice. The use of mature electrical clock recovery module while.avoiding optical-electrical-optical (O-E-O) operation may be potential in practical use.