All-optical switch with ultrahigh switching efficiency and ultralow threshold energy based on a one-dimensional PT-symmetric ring optical waveguide network

In this work, we propose an all-optical switch based on one-dimensional (1D) parity -time-symmetric (PT-symmetric) ring optical waveguide network (PTSROWN). By use of the resonant coupling effect of the PT-symmetric structure, the all-optical switch based on our designed 1D PTSROWN generates an ultrahigh transmissivity of 1.42 x 1018 at ON state, which breaks the bottleneck of the transmissivity of 1 at ON state produced by the all-optical switches made of dielectric optical waveguide networks, photonic crystals, microring resonators, and meanwhile, creates an ultralow transmissivity of 1.01 x 10-18 at OFF state. It causes our designing all-optical switch reproducing extraordinary large switch efficiency of 1.41 x 1036, which is 10 orders of magnitude greater than the optimal results reported yet. On the other hand, the super resonant coupling effects can also make the all-optical switch generate ultrastrong photonic localization at ON state, and then drastically reduce the threshold energy. In addition, we have deeply optimized the PT-symmetric optical waveguide network and obtain better extremum spontaneous PT-symmetric breaking points. On this condition, our designing all-optical switch can produce an ultralow threshold energy of 4.3 x 10-34 J, which is 12 orders of magnitude smaller than the best reported results. This not only provides a better choice for developing all-optical switching devices with better performance, but also possesses a broad application prospect in designing high-efficiency optical amplifiers, optical energy saver devices, etc.(c) 2022 Elsevier B.V. All rights reserved.