Nb5N6 microbolometers integrated with diffractive lens for THz imaging

We designed and fabricated Nb₅N₆ microbolometers integrated with five staircases square diffractive lens array (DLA) for THz detection. It gives us a method for designing diffractive lens to improve the coupling efficiency of the incident power into the Nb₅N₆ microbolometers. We measured the voltage response of the Nb₅N₆ microbolometer integrated with diffractive lens. We find it has 30 times larger response than of the Nb₅N₆ microbolometer without diffractive lens. Preliminary results for THz radiation show that Nb₅N₆ microbolometers integrated with diffractive lens array as room-temperature detectors yield good responsivity and noise equivalent power (NEP). In addition, we use one of these microbolometers in a THz imaging system for THz imaging. Development of a focal plane array (FPA) using such devices as detectors is favorable since DLA has many advantages, such as light weight, low absorption loss, high resolution, and the most important point is that DLA can be easily integrated by ready mass production using standard micro-fabrication techniques.