2-DIMENSIONAL BI-PERIODIC GRATING-COUPLED ONE-COLOR AND 2-COLOR QUANTUM-WELL INFRARED PHOTODETECTORS

Multiple quantum well infrared photodetectors (QWIP's) with two-dimens ional bi-periodic grating couplers have been demonstrated. For one-col or QWIP's, the response linewidths of such QWIP's are found to be much wider than those of conventional grating coupled QWIP's. The bi-perio dic gratings have also been applied to two color QWIP's to separately optimize the absorption at two wavelength bands. The large difference in responsivities at the two wavelength bands for devices with single period gratings can be greatly reduced with the use of bi-periodic gra tings.