Strategy for Low‐Loss Optical Devices When Using High‐Loss Materials

Abstract

Diverse materials, such as metal, graphene, highly doped semiconductors, and lithium niobate, have greatly enriched the functions of photonic devices such as thermo-optic, [1] electro-optic, [2] and all-optical modulators, [3] lasers, [4] photoelectric detectors. [5] However, there is a trade-off between the loss and performance of the material for photonic devices. Therefore, it is still challenging to reduce the loss of the devices without deteriorating the performances. To solve this problem, researchers have proposed to utilize highloss materials with superior materials such as lithium niobate for high-speed integrated modulators. [2aÀc,6] However, it is impossible to find an all-powerful material for various photonic devices.In recent years, material loss has been a powerful tool for optical field manipulation, [7] especially in the non-Hermitian system. Many counterintuitive phenomena in optics by utilizing high-loss materials [8] have been demonstrated in non-Hermitian systems. Coupled-mode theory in photonics systems containing gain and loss is applied to study the non-Hermitian systems. By carefully managing the gain and loss of the materials, the performances of the optical devices, [9] such as optoelectronic oscillators, [10] single-mode microring lasers, [8,11] sensing, [12] unidirectional invisibility, [13] and asymmetrical modes transmission [14] can be enhanced. Besides, in the passive non-Hermitian system, exciting findings are also observed in the loss-only structure. The novel properties of high-loss materials in a non-Hermitian system provide the potential method for high-performance optical devices and balance the trade-off between the loss and other performance metrics.This article proposes a method to realize low-loss optical devices with high-loss materials based on a two-waveguide-coupled non-Hermitian system. The results reveal that the loss of optical