上海科技大学知识管理系统

This work presents a theoretical investigation of an active photonic grating of the parity-time- (PT) symmetric architecture. The analytical study of the free-space mode propagation from the grating structure indicates the unique bifurcation property due to the PT-symmetry modulation. It is shown that both the gain-loss contrast and the lattice constant parameters are critical factors to modulate the active photonic system in between the PT-symmetry to the symmetry-broken phases. Furthermore, numerical simulations via the rigorous coupled-wave analysis (RCWA) method discover the existence of a unique spectral singularity phenomenon in this PT grating structure, which corresponds to a nontrivial single mode and near-zero bandwidth photonic resonant emission. Also, the guiding procedure for fulfilling spectral singularity modes is found to be related to the unique formation of the scattering matrix applied in the PT-symmetric photonic gratings. This theoretical work takes a fresh look into the active PT-symmetric photonic gratings focusing on the discovery of nontrivial free-space emission modes, which could contribute to the development of high-performance surface-emitting semiconductor devices. © 2022 American Physical Society.