光子晶体光纤产生飞秒超连续谱的实验研究

研究了飞秒脉冲经过光子晶体光纤时超连续谱产生的物理机制。采用输出波长可调谐的钛宝石光参量放大器作为泵浦源，光纤光谱仪测量不同泵浦功率和不同泵浦波长条件下光子晶体光纤产生的超连续谱的光谱图，对进行了归一化处理后的不同泵浦功率和不同泵浦波长条件下的超连续谱进行对比，分析影响光子晶体光纤超连续谱差异的物理机制。实验结果表明，当泵浦波长不变时，随着入射泵浦脉冲平均功率的增大，波峰增多，谱宽也逐渐加宽并伴随着出现能量向短波方向集中的现象，泵浦功率到达一定强度时，超连续谱的宽度最后到达饱和，谱的包络趋于稳定；入射光功率稳定在300 mW时，超连续谱的宽度和形状皆受到泵浦波长影响，在760～840 nm范围内，泵浦波长越长，波峰数越多，泵浦脉冲波长离零色散点越近，光子晶体光纤产生的超连续谱谱宽会越宽，超连续谱的形状相对越平坦。

Study on the Supercontinuum Generation with Femtosecond Pulse in Photonic Crystal Fiber

Physical mechanism of supercontinuum generation in photonic crystal fiber by femtosecond laser pulse has beeo investigated experimentally. In this study, we used the tunable output wavelength Ti: sapphire optical parametric amplifier as the pump source and the fiber spectrometer acquired the spectrogram of supercontinuum generation in photonic crystal fiber under different power and wavelength conditions, then we normalized the spectrograms and make a comparison of them. PCF supercontinuum differences affected by physical mechanisms were analyzed. We found that when increasing the incident pump pulse power, the spectral width will be gradually widened, there are more peaks, part of the energy will transfer in to the short-wavelength region; as long as it reaches a certain intensity, width of supercontinuum finally saturated, the shape of supercontinuum was also stabilized. As the incident power was settled at 300 milliwatt and the length of PCF was settled at 105 millimeter, experimental results show that width and shape of supercontinuum are affected by the wavelength of pump pulse, in the range of 760 to 840 nm, there appears more and more peaks with the increase of incident wavelength; at anomalous dispersion the spectrogram of supercontinuum generation will be more flat and more wider as the wavelength of pump pulse closer to zero point.