Achieving exact balance between spatially separated gain and loss is generally regarded as a necessary condition for parity-time- (PT-)symmetric optical systems. We introduce generalized PT- (GPT-)symmetric optical structures, which have an asymmetric and unbalanced gain-loss profile, while exhibiting similar scattering properties and phase transitions as their traditional PT-symmetric counterparts. In particular, we show that the concept of GPT symmetry may help to reduce the threshold gain in achieving newly discovered PT-enabled applications, such as the coherent perfect absorber laser and exceptional points. The concept proposed herein will facilitate the practice of PT-symmetric optical and photonic devices by offering greater design flexibility to tailor gain-loss profiles and their thresholds.
Maryam Sakhdari, N. Mohammadi Estakhri, Hakan Bagci, and Pai-Yen Chen, “Low-Threshold Lasing and Coherent Perfect Absorption in the Generalized PT-Symmetric Optical Structures,” Physical Review Applied, Vol. 10, No. 2 (8 Pages) 024030, August 21, 2018. https://doi.org/10.1103/PhysRevApplied.10.024030.
American Physical Society