| Fiber Raman amplifiers (FRA) have been a key technology for extending the reach and capacity of dense wavelength division multiplexed (DWDM) fiber communication systems because of its several advantages: high gain, high saturated output power, low noise, flexible use of signal wavelengths, a broad gain bandwidth, retained optical signal level and simple configuration. In this dissertation, the theoretical and experimental studies on the lump fiber Raman amplifier and the design of model machine have been carried out. The main points are as follows:1. The gain and noise properties of FRA are synthetically studied. The influence of the fiber length, pumping configuration, signal power, pump power on the gain and noise performance have been analyzed. In particularly, the issue on power conversion efficiency (PCE) is discussed.2. A high efficient and stable algorithm for the optimization of pump power distribution is proposed. The algorithm is based on the nonlinear model of FRA. In the algorithm, the pump power distribution and output gain characteristic (gain level and gain flatness) are regarded as the input and output varies of the nonlinear model, respectively. The algorithm has fast global convergence and favorable stability because of the hybrid method by introducing the continuation method based on Newton's iteration.3. An algorithm for the optimization of pump wavelength and pump power in lump amplifier is proposed. The algorithm is based on the pump power integral model. In the algorithm, the hybrid method is applied to obtaining the optimal pump wavelengths and the quadratic programming is used to solving the optimal pump power integral. Thus, the amount of seeking varies reduces. The high speed of hybrid algorithm and the decrease of seeking range evidently increase the computing speed of the algorithm. For the first time, to our knowledge, the correction method of initial losses item has been proposed, which make the algorithm based on the pump integral model be applied to the optimization problem in the large signal, high gain lump amplifier.4. The synthetically research of gain clamping technology using lasing feedback has been carried out. For the first time, to our knowledge, the effect of the direction of pump light and lasing light on the performance in the coupler-based clamping configuration have been analyzed, the difference of the character and performance in three clamping configuration (the coupler-based clamping configuration, the hybrid clamping configuration and the circulators-based clamping configuration) has been discussed. Furthermore, the influence of the lasing wavelength and the depth of feedback on the clamping performance in different clamping configurations are discussed. Based on the research above, some advices about the optimization for gain clamping are proposed.5. The first domestic dispersion-compensating C plus L band lump fiber Raman amplifier model machine has been successfully realized and experimentally tested. The machine contains pump sources and all fiber components, and then realizes the miniaturization. For the first time, to our knowledge, the combined circuit containing analogue and digital circuit is adopted for the adjustment of laser current, the monitor and control in digital mode. This design scheme is the base of the future intelligentized fiber Raman amplifier. The bandwidth of the amplifier is 75nm (1530-1605nm). It can provide a net gain higher than 10dB. The gain flatness is about 0.9dB and the noise figure is lower than 7dB at the net gain about 10dB.
|
PDF Full Text Request