A superior coherent perfect absorber and laser constructed from the periodic ring optical waveguide network based on extremum spontaneous PT-symmetric breaking points

Abstract

In this study, we propose a superior coherent perfect absorber and laser (CPA laser) constructed from the one-dimensional (1D) two-material (TM) parity-time (PT) symmetric periodic ring optical waveguide network (PROWN). A novel method based on seeking the exact extremum spontaneous PT-symmetric breaking points is used for determining the imaginary part of the refractive indices of the materials composed of waveguides. The minimal overall output coefficient and maximal transmissivity can reach and , respectively, which are 9 orders of magnitude smaller and larger than the previously reported values, respectively. It is also found that with the increment of unit cells, increases monotonically while decreases monotonically. Moreover, and are found to be varied with the periodicity of 1.866152 MHz. Our work provides a new method for optimizing CPA lasers.