飞秒激光在锥形镀膜探针传输中相位奇异的研究

利用数值模拟的方法对飞秒激光脉冲中光波振荡一个周期内不同时刻的光场进行了计算、比较, 获得了输出端平面内各空间点处光场的最大值及达到最大值时对应的时间, 得到了探针近场的振幅和相位分布. 在研究振幅分布的过程中发现, 在探针输出端的有些区域振幅始终为零, 即在光波振荡的一个周期内这些区域始终为相位奇异点; 通过分析相位分布得到了相位奇异随时间的演化及相位奇异的特点.

Phase singularities in femtosecond laser pulses transmitting through optical fib er prob es

The near-field distribution of a light wave in a metal-coated optical fiber probe under the illumination of femtosecond laser pulses is numerically simulated. By choosing the maximum of the calculated light field data and the time when the light field reaches the maximum in a time period of one light wave cycle at each spatial point, we obtain the amplitude and phase distributions of the light field near the probe. We find that the output amplitude distribution of y-polarization has roughly a circled-cross-like pattern with two arc-like zero-amplitude zones. The zeros of light intensity are the phase singularities at which the phase is undefined. By analyzing the output phase distribution of y-polarization, we obtain the temporal evolution of the phase singularities and their characteristics