在远离光子晶体光纤零色散波长的正常色散区入射飞秒脉冲产生四波混频及孤子效应的实验研究

在远离光子晶体光纤零色散波长的正常色散区入射飞秒脉冲,实验产生了一对由四波混频引起的信号波带和闲频波带,及一对由脉冲内拉曼散射和非孤子辐射引起的孤子和色散波带,并观察到功率饱和现象.利用有限元法理论模拟了光纤的色散和非线性特性,用四波混频的相位匹配条件模拟了光纤在满足相位匹配条件下所产生的信号波带和闲频波带出现的可能位置,并与实验结果符合得很好.结果表明:即使在光子晶体光纤的正常色散区抽运激光脉冲亦可以产生四波混频和孤子效应;研究发现四波混频的产生是由四阶色散参量引起的;并进一步从理论上解释了孤子及色散波的产生原因.

Experimental research of four-wave mixing and soliton effects in a photonic crystal fiber pumped femtosecond pulses at the wavelength located normal dispersion regime away from the zero dispersion point

In this paper, we show experimentally that a pair of signal wave and idler wave bands is generated by four-wave mixing, and a pair of optical solitons and dispersion wave bands is induced by intrapulse Raman scattering and non-soliton radiation, and we also observe the power saturation phenomenon of the photonic crystal fiber (PCF) by using the incident femtosecond pulses in normal dispersion region away from the zero-dispersion wavelength of the PCF. The dispersion and nonlinear characteristics of the PCF are studied by the finite element method. The possible positions of the signal wave band and the idler wave band that is generated in the fiber satisfying the phase-matching condition are simulated by four-wave mixing phase matching, the results are in good agreement with the experimental results and show that even the pump laser pulse in the normal dispersion region can also produce the PCF four-wave mixing and optical solitons effects. In the present study it also revealed that the four-wave mixing experiment is generated by the fourth-order dispersion parameter β₄, and the origins of optical solitons and dispersion wave bands generation are further explained.
Keywords： photonic crystal fiber normal dispersion region four-wave mixing optical solitons