Investigation of Broadband Flattening Amplification Characteristics in PT-Symmetric Photonic Crystals Based on Multiple Defect Coupling

This paper presents a crystal structure based on PT-symmetric photonic crystals with multi-defect coupling, achieving wideband and flat gain in the near-infrared region. The transmission matrix method is employed to analyze the influence of material and structure parameter variations on the wideband amplification characteristics of the PT symmetric photonic crystals. Through the adjustment of the refractive index and thickness of the gain-loss medium, the adjustment of the passband transmission and the improvement of the flatness of the photonic crystal can be realized. In the near-infrared band of $\boldsymbol{1433}\mathbf{nm}\boldsymbol{\sim 1596}\mathbf{nm}$ , the broadband amplification with an average transmission of 6.7835 can be realized, and it has good flatness. This research has broad prospects for applications in high-efficiency optical amplification, photonic crystal lasers, and high-efficiency optical filters.