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目前产生超连续谱大多采用全内反射光子晶体光纤,光谱宽度达两个倍频程,但无法对其位置和宽度进行主动控制。全固态光子带隙光纤的带隙效应具有光谱滤波功能,通过设计全固态光子带隙光纤的带隙和带隙内色散特性,可产生特定范围内的超连续谱输出,同时色散特性受纤芯直径影响很小,有利于光谱可控的大功率超连续谱产生。根据1.064μm的抽运脉冲激光的需要,设计了全固态光子带隙光纤,并计算了第一带隙内的色散、损耗及非线性系数等参数。通过与波长有关的损耗将带隙效应引入到广义非线性薛定谔方程中,模拟了飞秒脉冲在全固态光子带隙光纤中传输的时域和频谱演化,得到带隙内超连续谱输出。比较了在有无带隙的情况下,飞秒脉冲的时域和频谱在带隙光纤中随传输距离的演化,分析了带隙效应对超连续谱产生的影响。
At present, most of the supercontinuums are produced by total internal reflection photonic crystal fiber with spectral width of two octaves, but their position and width can not be controlled actively. The bandgap effect of an all-solid-state photonic bandgap fiber has a spectral filtering function that produces a supercontinuum output within a specific range by designing the bandgap and in-band dispersion characteristics of an all-solid-state photonic bandgap fiber while the dispersion characteristics are affected by the core The effect of diameter is small, which is conducive to the generation of high power supercontinuum with controlled spectra. According to the needs of the 1.064μm pump pulse laser, an all-solid-state photonic bandgap fiber is designed and the parameters such as dispersion, loss and nonlinear coefficient in the first bandgap are calculated. The bandgap effects are introduced into the generalized nonlinear Schrödinger equation through wavelength-dependent losses. The time-domain and spectral evolution of femtosecond pulses in an all-solid-state photonic band-gap fiber is simulated to obtain the supercontinuum output in the bandgap. The time-domain and frequency spectra of femtosecond pulses in a band gap fiber were compared with those in the presence or absence of band gaps to analyze the effect of bandgap effects on the supercontinuum generation.