High‐Performance Chiral Mode Switching Devices Using Silicon Metamaterial Waveguides Beyond 1.55 µm

Abstract

Dynamically encircling exceptional points (EPs) in non‐Hermitian systems has garnered considerable attention for enabling chiral mode switching, where the nature of the output mode is determined solely by the encircling handedness. However, typical chiral transmission devices primarily operate within the 1.55 µm waveband and encounter the wavelength‐dependent mode mismatch, which constrains operational range and degrades mode purity. In this study, we address these limitations by introducing metamaterial waveguides to tailor the requisite optical properties and achieve ultra‐broad‐bandwidth and ultra‐high‐purity chiral mode switching at 1.55 µm and beyond. Simulation results spanning the optical communication and 2 µm wavebands show near‐unity transmission efficiency and high mode purity (> 98.8%) across a record 500 nm bandwidth. Moreover, experimental results at 2 µm waveband reveal an average transfer efficiency of < 1 dB and high mode purity exceeding 95% within a setup‐limited bandwidth of 85 nm. This work paves the way for achieving high‐efficiency and high‐purity chiral transmission devices in the near/mid‐infrared ranges, presenting compelling prospects for future practical EP‐based devices and applications.