Theoretical Analysis And Experimental Research On All Optical 3R Regeneration

In high speed and long haul optical-transport-network, optical signal are affected by several deteriorative factors, which increase bit error ratio and limit transmission distances. For this reason, signal regeneration is necessary in transmission systems. All optical 3R regeneration, overcoming the bottle neck effect in electric regeneration, is an effective method to guarantee the quality of transmission. A novel all optical 3R regenerator is proposed in this dissertation, where high finesse Fabry-Perot (F-P) filter is used in clock recovery and SOA is used in the optical decision gate. A new 40Gbit/s optical signal can be regenerated from the degraded optical signal using this regenerator. In this dissertation, the scheme of which is been further discussed theoretically and experimentally.Nonlinear property of SOA is deeply analyzed, as it is an important component of all-optical 3R regeneration both in clock recovery and in decision gate. The wavelength conversion based on SOA is numerically emulated. The influence of the wavelength conversion parameters on the output pulse is discussed in detail based on the cross gain modulation. A method is proposed to eliminate the pattern effect of regenerated pulse with narrow band filter based on the cross phase modulation, and the reason of positive code output of wavelength conversion is studied. The experiment on wavelength conversion at 10 and 40Gbit/s is performed, which proves the conclusion theoretically and the result of numerical simulation. By analyzing SOA for the transport function of frequency, we conclude that low-frequency component of signal can be suppressed by SOA, then this conclusion is proved through experiment.F-P filter, the key component, is shown to have the ability of extracting clock pulses from data signals, which has been proved in time and frequency domains. The process of clock recovery is modeled to find out how the differential finesses of F-P filter affects the quality of clock pulses. The conclusion is obtained that increasing the fitness of F-P filter can depress amplitude noise and timing jitter of output pulses, and it can slow down the pulse amplitude dropping when the input signal is continuum"0"code. In the 40Gbit/s clock recovery experiment, for solving the problem that input wavelength of aligning to the F-P filter, the information carried by the input data signal pulses is transferred to a continuous wave from a laser with a steady central wavelength using a wavelength converter, then the clock can be extracted using F-P filter with high finesses. The low frequency noise in the clock is suppressed by using SOA, and the 40GHz clock signal is obtained.The scheme of 10Gbit/s packet clock recovery based on F-P filter is also proposed. To decrease building time and die-out time, the F-P filter with low fitness is employed. The 10Gbit/s packet clock pulses are extracted successfully in experiment.40Gbit/s all optical 3R regeneration experiment is performed finally. The 3R regenerator succeeds in transforming the data signal from deteriorated pulses into acceptable pulses. The regenerated signal has been tested and found there is less noise, less timing jitter, and higher signal noise ratio than input data signal.