利用自发四波混频测量光子晶体光纤色散

Dispersion Property Measurement of Photonic Crystal Fiber by Using Spontaneous Four Wave Mixing

使用脉宽为1.6ps的脉冲光抽运0.6m长的光子晶体光纤,测量由光纤中自发四波混频过程所产生光子对的频谱,并利用所获得的相位匹配数据确定了待测光纤的色散。当抽运光的中心波长以1nm的步长,在1037～1047nm的范围内变化时,通过可调谐滤波器和单光子探测器测量光子晶体光纤产生的信号和闲频光子对的频谱,从而获得11组四波混频相位匹配数据。然后使用阶跃有效折射率模型对所获得的相位匹配数据进行拟合,得出待测光子晶体光纤的纤芯半径和包层空气比的有效值分别为0.949μm和29.52%,并在此基础上计算了光纤的色散及全频谱范围内的四波混频相位匹配曲线。实验结果显示,曲线预测值与实测值之间误差小于0.1%。

The dispersion property of a 0.6 m-long photonic crystal fiber （PCF） is deduced by characterizing its phase matching condition of spontaneous four wave mixing （SFWM） through pumping the PCF with a pulse train having a pulse duration of 1.6 ps. When the central wavelength of the pump is varied from 1037 to 1047 nm with a step of 1 nm, the spectra of signal and idler photons via SFWM are measured by using tunable filters and single- photon detectors. Using the step effective index model, and fitting the 11 sets of experimentally obtained data of SFWM phase matching, the effective core radius and air fraction of the PCF are found to be 0. 949 μm and 29.52 %, respectively. Accordingly, the dispersion property and the SFWM phase matching curve of the PCF in the whole spectral range are then calculated. Experimental results show that the predicted wavelengths of phase matching agree with the measured values, and the differences are less than 0.1%.