锥形镀膜光纤探针中飞秒激光脉冲的传输

Propagation of femtosecond laser pulses through metal-coated tapered fibre probe

采用三维时域有限差分法对飞秒激光脉冲照明下锥形镀膜光纤探针内的光场进行了计算,研究了飞秒脉冲在探针中传输时的时域、频谱和相位特性,并分析了不同锥角和不同长度的探针对这些特性的影响.研究结果发现飞秒脉冲在探针中传输时出现了脉冲展宽、幅值振荡以及频谱分裂等现象,并且利用频谱和相位的变化特性初步解释了脉冲的展宽和脉冲振幅随时间周期性变化等现象.

Using the three-dimensional finite difference time domain （3D-FDTD） method, we calculate light field in metal-coated optical fiber probes with different taper angles and different lengths under illumination of femtosecond laser pulses. The transmission of temporal fields of the laser pulses propagating in the probes and the properties of their frequency spectrum and phases are studied. The influences of the taper angle and the length of the probe on these properties are analyzed. The calculation results show that the structure of probe leads to the broadening, amplitude oscillation and the spectrum splitting of the laser pulses. With the analysis of the spectrum and the phase variation, we give a preliminary explanation to the phenomena of the pulse broadening and the periodic variation of the pulse amplitude with time.