利用参量放大效应测量光纤的非线性系数和色散参数

通过对理想条件下得出的光纤参量放大增益解析解和相位匹配关系表达式进行修正,得出在光纤有损耗 时,小信号峰值增益和光纤非线性系数成正比以及光纤色散参数和峰值增益波长与抽运光波长的差成反比两个近 似表达式。以此为基础提出:只要在直流抽运光作用下测出小信号峰值增益以及增益峰值波长与抽运波长之差, 然后通过简单的代数运算就可以得出光纤的非线性系数和色散参数。实验中,分别用两个不同波长的抽运光,对 一卷长度为1450m的高非线性色散平坦光纤(HNLF)的非线性系数和色散参数进行了测量。测得非线性系数为 γ=11.8W-1·km-1,色散斜率在1550nm附近为S=0.0157ps/(nm2·km)。其中,色散斜率测量值和商家给定的 值之间误差不超过5%。对在测量中抽运光和信号光之间由于拉曼放大作用所带来的增益谱不对称性进行了讨论。

Nonlinear Coefficient and Dispersion Parameters Measurement Utilizing Optical Parametric Amplification

The analytical relations of parametric peak gain versus fiber nonlinear coefficient and fiber dispersion versus the difference between gain peak and pump wavelengths were derived when the fiber loss was taken into account, based on which a new method to measure the nonlinear coefficient and dispersion parameters was proposed with only simple algebraic calculation required. In the experiment, a 1450-m-long highly nonlinear dispersion flattened fiber (HNLF) was measured by using two different pump wavelengths, the measured nonlinear coefficient was γ=11.8 W-1?km-1, and the dispersion slope was S=0.0157 ps/(nm2?km) with the error from the value given by the manufacturer below 5%. The measured asymmetry of gain spectrum ascribed to the Raman effect was discussed.