HOLOGRAPHIC FOURIER DIFFRACTION GRATINGS WITH A HIGH DIFFRACTION EFFICIENCY OPTIMIZED FOR OPTICAL COMMUNICATION-SYSTEMS

Novel diffraction gratings in a near-infrared region that is specially optimized for optical communication systems are studied and demonstrated by using a simple holographic exposure process. These gratings have a unique groove profile. The gratings of 770 lines/mm have a very high efficiency of 95% at a wavelength of 1.31-mu-m and more than 85% at a wavelength of 1.52-mu-m for nonpolarized light in the Littrow mounting. They also show a very low dependence (less than 2%) of the efficiency on the polarization.