A metal cascaded resonant cavity structure to enhance responsivity of photodetctor

A cascaded resonant F-P cavity structure is proposed to improve the responsivity of high-speed photodetector, which consists of subwavelength metal grating and metal film. Responsivity enhancement can be achieved by high light transmittance and high quantum efficiency, simultaneously. High transmission arises from slit cavity mode resonance of subwavelength metal grating, and high quantum efficiency is due to adopting resonant cavity enhanced structure. In our proposed photodetctor structure, subwavelength metal grating plays a very important role in performance enhancement. The results show that responsivity can be increased about 31 times compared to the conventional photodetector by optimizing the structure parameters.