Non‐Reciprocal Terahertz Topological Sensor on a Silicon Chip

Abstract On‐chip non‐reciprocal light‐matter interaction improves sensor performance by leveraging direction‐dependent differences in detection signals. Here, the experimental realization of a non‐reciprocal terahertz topological sensor (NTTS) is reported through magneto‐optical integration on a silicon valley photonic cavity chip, enabling dual‐frequency non‐reciprocal sensing. Through sensing the ultrathin polyimide membranes of varying thicknesses, non‐reciprocal group delay sensitivities of 0.46 and 0.24 ns µm⁻¹ are demonstrated for the detuned clockwise and counterclockwise cavity modes, respectively. NTTS also provides non‐reciprocal sensitivity in the position sensing experiment, yielding group delay sensitivities of 2.63 and 3.21 ns mm⁻¹. This non‐reciprocal topological sensor enables a new sensing paradigm and can be integrated into compact topological photonic circuits for on‐chip gyroscope, biochemical sensors, and environmental monitors.