Kerr nonlinearity effect on light transmission in one dimensional photonic crystal

TL;DR

This study numerically explores how Kerr nonlinearity influences the transmission spectrum of a one-dimensional photonic crystal, revealing effects on band gap width, light localization, and angle-dependent transmission properties.

Contribution

It provides new insights into how Kerr nonlinearity sign and strength affect photonic band gaps and transmission, including the critical nonlinearity where the crystal becomes transparent.

Findings

Self-focusing nonlinearity increases PBG width and causes light localization.

Defocusing nonlinearity can decrease PBG width up to a critical point, then reverse.

Transmission minimum increases with incident angle, polarization-independent.

Abstract

We investigate numerically the effect of Kerr nonlinearity on the transmission spectrum of a one dimensional $\delta$-function photonic crystal. It is found that the photonic band gap (PBG) width either increases or decreases depending on both sign and strength of Kerr nonlinearity. We found that any amount of self-focusing nonlinearity $(\alpha >0)$ leads to an increase of the PBG width leading to light localization. However, for defocusing nonlinearity, we found a range of non-linearity strengths for which the photonic band gap width decreases when the nonlinearity strength increases and a critical non-linearity strength $|\alpha_{c}|$ above which the behaviour is reversed. At this critical value the photonic crystal become transparent and the photonic band gap is suppressed. We have also studied the dependence on the angle of incidence and polarization in the transmission spectrum of our one-dimensional photonic crystal. We found that the minimum of the transmission increases with incident angle but seems to be polarization-independent. We also found that position of the photonic band gap (PBG) shifts to lower wavelengths when the angle of incidence increases for TE mode while it shifts to longer wavelengths for TM mode.