Non-Reciprocal Terahertz Topological Sensor on a Silicon Chip

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.