Optomechanical Infrared Detector Monolithically Integrated with Micro-Metalens Array

Abstract

The optomechanical uncooled infrared (IR) detector, based on the bimaterial microcantilever thermal deformation, has proved to have great potential due to the ability to measure IR using visible-spectral-range components. However, like most types of detectors, they encounter the common limitation of a low fill factor, leading to an inefficient utilization of light energy. The metalens, with a compact footprint, high design flexibility, and MEMS (microelectromechanical systems) compatibility, is expected to be integrated with IR detectors to enhance performance. Here, we present the design, fabrication, and characterization of a monolithic integration of a long-wavelength infrared (LWIR) micrometalens array and an optomechanical IR detector. A microfabrication process was developed to successfully prepare such an optomechanical IR detector with a monolithically integrated micrometalens array, where the micrometalens array was directly fabricated on the back of the detector substrate. Experimental results demonstrate that the integration of the micrometalens array markedly amplifies the responsivity of the optomechanical detector within the 8–14 μm wavelength band, achieving an enhancement of 81.8%.