LONG-PERIOD 2-DIMENSIONAL GRATINGS FOR 8-12-MU-M QUANTUM-WELL INFRARED PHOTODETECTORS

By considering all possible high order diffracted waves, the authors i nvestigate the spectral response of two-dimensional gratings for quant um well infrared photodetectors (QWIPs). A new method is proposed that using long period gratings may improve grating quality and reduce the resulting cross talk in grating-coupled QWIPs. A sensitivity analysis indicates that the influence of variation of the grating constant on the coupling efficiency is less sensitive for the long period gratings than for the short ones. A large coupling efficiency has been demonst rated for long period gratings. The calculated wide grating response s pectra are in good agreement with the experiment result. (C) 1996 Amer ican Institute of Physics.