Electromagnetic modeling of quantum-well photodetectors containing diffractive elements

An analytical approach for modeling optical fields in quantum-well infrared photodetectors was developed by using a rigorous solution of the corresponding electromagnetic problem. Its application includes structures having a large number of dielectric layers, which may contain gratings having arbitrary profiles and metal-strip arrays acting as electrodes. By representing the fields inside complex photodetector structures in terms of interconnected transmission-line units, this approach helps considerably to clarify the role of each constituent of the photodetector. Examples involving realistic situations reveal that the presence of metal electrodes may affect the photodetection operation in a large class of grating structures. In particular, we show that the sensitivity of specific photodetector configurations can be enhanced by choosing grating parameters that optimize the overall photodetecting performance.