Mid-wavelength infrared photodetection and surface plasmon enhancement

Abstract

Infrared (IR) photodetectors with peak sensitivity wavelength in mid-wavelength infrared (MWIR) spectral window (3-5 μm) have attracted extensive interests due to the highest atmospheric transmission in this range. Traditional photodetectors operating in this wavelength range are mainly based on HgCdTe, PbSnTe and InSb, which either have difficulties in repeatable growth of uniform composition bulk crystals and epitaxial layers or need low temperature environment, which lead to the development of alternative material systems, such as InAs/GaSb type-II superlattice (SL) and InAsSb based material system. To improve high temperature performance of photodetectors, a concept of surface plasmon polariton (SPP) enhancement has been proposed in recent years. By placing a plasmonic structure which has strong light focusing capability in sub-wavelength regime, close to absorption region of a detector, tight spatial