Antenna-coupled terahertz electromechanical bolometer

The advancement of terahertz sensing and imaging applications is contingent upon the development of detectors that are compact and low-noise and operate reliably at room temperature. Traditional terahertz bolometers are often constrained by limited absorption efficiency, low sensitivity, slow response times, and bulky architecture. We demonstrate an antenna-coupled microelectromechanical system bolometer for terahertz detection, featuring a spiral-shaped niobium antenna suspended above an air cavity on a cyclic olefin copolymer substrate and backed by a gold plate with periodically arranged square apertures. The spiral operating as efficient terahertz absorber, thermal transducer, and mechanical resonator makes the device compact and enhances sensitivity and responsivity. Upon exposure to terahertz radiation near the absorption peak of the structure, thermal expansion induces a redshift in the mechanical resonance frequency of the spiral, which is detected using a laser vibrometer through the rear gold plate. Experimental measurements show a clear resonance shift from 12.25 to 11.16 kHz under incident terahertz radiation at 278 GHz, with power levels ranging from 0 to 0.9 mW. This result corresponds to a thermomechanical responsivity of ∼1200 Hz/mW. Operating at room temperature and relying on monolithic implementation, the proposed device offers a sensitive, compact, and scalable platform for terahertz sensing and imaging applications.