Biswas Piyali, Gandhi Harsh K, Mishra Vaibhab, Ghosh Somnath
Appl Opt. 2018 Sep 1;57(25):7167-7171. doi: 10.1364/AO.57.007167.
We report an asymmetric behavior of optical pulses during their propagation through a time-varying linear optical medium. The refractive index of the medium is considered to be varying with time and complex, such that a sufficient amount of gain and loss is present to realize their effect on pulse propagation. We have exploited the universal formula for optical fields in time-varying media. Numerically simulated results reveal that pulses undergo opposite temporal shifts around their initial center position during their bi-directional propagation through the medium along with corresponding spectral shifts. Moreover, the peak power and accumulated chirp (time derivative of accumulated phase) of the output pulse in both propagation directions are also opposite in nature, irrespective of their initial state. Numerically simulated behavior of the pulses agrees well with the analytical solutions.
我们报道了光脉冲在通过随时间变化的线性光学介质传播过程中的一种不对称行为。该介质的折射率被认为随时间变化且为复数，从而存在足够量的增益和损耗以实现它们对脉冲传播的影响。我们利用了时变介质中光场的通用公式。数值模拟结果表明，脉冲在沿介质双向传播过程中会围绕其初始中心位置发生相反的时间偏移，同时伴有相应的光谱偏移。此外，无论其初始状态如何，在两个传播方向上输出脉冲的峰值功率和累积啁啾（累积相位的时间导数）在性质上也相反。脉冲的数值模拟行为与解析解非常吻合。
