Fast response of superconducting hot-electron bolometers with a twin-slot nano-antenna for mid-infrared operation

In this study, the use of nano-antennas to improve the response performance of infrared detectors is proposed, and the design and fabrication of antennas that operate in the infrared range is demonstrated. Prototypes of a mid-infrared superconducting hot-electron bolometer (HEB) formed by a twin-slot antenna with a niobium nitride strip were fabricated. When the bolometer was irradiated with mid-infrared (λ = 4.89 μm) pulsed light, responses with clear polarization dependency were observed. When the HEB was biased close to the critical current under mid-infrared pulsed light irradiation, the detector output synchronized with the trigger signal was observed. The output waveforms comprised voltage pulse trains, and the full width at half maximum of the pulse was evaluated to be approximately 0.3 ns.