宏观弯曲效应对ZBLAN光纤中红外超连续光谱产生的影响

Influences of Macroscopic Bending on Mid-Infrared Supercontinuum Generation in ZBLAN Fibers

基于数值模拟方法研究了弯曲效应对ZBLAN光纤中红外超连续光谱产生的影响。利用有限元方法分析了宏观弯曲效应对不同数值孔径ZBLAN光纤的限制损耗、色散和非线性特性的影响,计算出ZBLAN光纤的弯曲截止波长,基于广义非线性薛定谔方程模拟了ZBLAN光纤中红外超连续谱产生的演化过程。研究发现,在未发生弯曲的情况下,非线性系数在中红外波段迅速下降会限制低数值孔径ZBLAN光纤中的光谱展宽;在发生弯曲时,当孤子中心频率接近弯曲损耗边界时,孤子自频移效应被抑制,光谱展宽停止。

The effect of mid-infrared supercontinnum generation in ZBLAN fibers is numerically investigated.Based on the finite element method, the influences of macroscopic bending on confinement loss, dispersion and nonlinearity of ZBLAN fibers with different numerical apertures are analyzed, and the bending cut- off wavelength of ZBLAN fibers is figured out. The evolution of mid- infrared supercontinuum generation in ZBLAN fibers is simulated by using the general nonlinear Schr？dinger＇s equation. The results indicate that the drastic dropping of nonlinear coefficient in mid- infrared wavelength region suppresses the spectral broadening of ZBLAN fibers with low numerical aperture when no bending is applied. In the presence of bending, when the central frequency of the soliton approaches the boundary of bending-induced loss region, the soliton selffrequency shift effect is suppressed and the spectral broadening phenomenon is radicated as well.