Broadband Asymmetric Light Transport in Compact Lithium Niobate Waveguides

Abstract Asymmetric on‐chip light transport is important but always challenging for photonic integrations. Although it has been recently implemented by adiabatically encircling the exceptional points in a non‐Hermitian system, these approaches are fundamentally restricted to the adiabatic condition that brings disadvantages of low transmission efficiency and large device footprint. Here, it is proposed to realize a broadband asymmetric light transport in compact non‐Hermitian coupled waveguides on the lithium niobate‐on‐insulator (LNOI) platform. The asymmetric function is fulfilled by a particular mode selection in a loss‐controlled LNOI waveguide triplet, where a lossless zero mode plays a crucial role. Moreover, the shortcut to adiabaticity is applied to speed up the light evolution and shorten the device length. The approach works out a new strategy to establish an asymmetric light transport in a compact form, indicating further new on‐chip light manipulations in this promising LNOI photonic platform.