光源的稳定性对拍信号在非线性光子晶体光纤中演化的影响

Influence of Light Source Stability on Evolution of Beat Signal in Nonlinear Photonic Crystal Fibers

人们通常利用拍频光信号的传输光谱演化来测量光纤的非线性系数。通过数值模拟分析了光源输出光功率和中心频率的扰动以及光源谱线宽度对该测量方法的影响,并进行了实验验证。使用紧凑的超格子算法分析了一种光子晶体光纤(PCF)的传输特性。考虑自相位调制(SPM)、损耗和群速度色散,采用分步傅里叶方法分析了拍频光信号沿光子晶体光纤的传输过程,得到了信号频谱演化的数值仿真结果。结果表明光源输出功率的扰动基本不会影响非线性系数的测量结果,但输出波长的扰动和光源的谱宽对非线性系数的测量有一定影响。因此需要选择适当的参数条件才可得到较为精确的实验结果。

At present, the spectrum evolution of the beat signal can be used to measure the fiber nonlinear coefficient. By theoretical simulations, the effect of the stability of the output power, the frequency and the linewidth of the laser on the measurement of the nonlinear coefficient were analyzed. The simulations agree well with the experiments. The propagation properties of a kind of photonic crystal fiber （PCF） are analyzed with the compact supercell method. Taking self-phase modulation （SPM）, fiber loss and dispersion into account, the transmission process and the evolution spectra of the beat signal propagating along the PCF are analyzed by using the split-step Fourier method. The results show that the stability of the laser output power has little effect on the measurement of the nonlinear coefficient, but the linewidth and the stability of the central wavelength have more effects on it. Proper parameters should be established to get a more accurate measurement result, in order of the nonlinear coefficient.