Wavelength selective wideband uncooled infrared sensor using a two-dimensional plasmonic absorber

Abstract

A wavelength selective wideband uncooled infrared (IR) sensor that detects middle-wavelength and long-wavelength infrared (MWIR and LWIR) regions has been developed using a two-dimensional plasmonic absorber (2D PLA). The 2D PLA has a Au-based 2D periodic hole-array structure, where photons can be manipulated using the surface plasmonlike mode. Numerical investigations demonstrate that the wavelength of the absorption can be designed according to the surface period of holes over a wide wavelength range (MWIR and LWIR regions). A microelectromechanical system (MEMS)-based uncooled IR sensor with a 2D PLA was fabricated using complementary metal oxide semiconductor (CMOS) and micromachining techniques. The 2D PLA was formed from a Au layer sputtered on a perforated oxide layer. A reflection layer was introduced to the backside of the 2D PLA to prevent additional absorption. Measurement of the spectral responsivity shows that selective enhancement of responsivity is achieved over both MWIR and LWIR regions, where the wavelength of the responsivity peak coincides with the hole period of the 2D PLA. The results obtained here provide direct evidence that a wideband wavelength selective IR sensor can be realized simply by design of the 2D PLA surface structure without the need for vertical control in terms of gap or thickness. A pixel array where each pixel has a different detection wavelength would be developed for multicolor infrared imaging using standard CMOS and micromachining techniques.