Phase-Change Nonreciprocal Metasurface: From One-Way Transmissive Color Filtering to Broadband Optical Limiting

We present a tunable multilayer optical metasurface that exhibits nonreciprocal light transmission and power-limiting response using phase-change material antimony trisulfide (Sb<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>S3). In the amorphous state, the device acts as a one-way transmissive optical filter, selectively allowing specific wavelengths to pass in the forward direction while suppressing backward transmission. Upon crystallization, it transitions into a broadband optical limiter, absorbing/reflecting most of the incident light and preventing transmission in both directions. Numerical simulations confirm a highly asymmetric light transmission and power-limiting performance of the proposed structure, making it a promising candidate for nonreciprocal and sensitive photonic devices.