On-chip THz photonic receivers with built-in frequency selectivity

Miniaturized terahertz (THz) photonic receivers with built-in frequency selectivity are crucial for integrated THz sensing and communication systems. Silicon photonic crystal waveguides (PCWs) provide a dispersion-engineered platform for THz guiding, yet realizing compact, highly sensitive, and well-isolated multi-channel receivers on a single chip remains challenging. Here, we demonstrate an integrated three-channel THz photonic crystal detector based on an isosceles-triangle-lattice PCW side-coupled to multiple point-defect cavities, each hosting a monolithically integrated Nb5N6 microbolometer. Three spatially separated cavities define distinct narrowband channels around 0.43 THz for on-chip frequency-division-multiplexed detection. By converting a single silicon PCW into a scalable, frequency-division-multiplexed detector array, this work offers a practical route toward integrated THz spectrometers and multi-band front ends for on-chip THz microsystems.