A new binary multi-layer diffraction grating

In WDM communication systems, diffraction grating is an important component. Optical components such as multiplexers use diffraction grating in their structures. In these devices, a grating with good specification (high angular dispersion, high diffraction efficiency, and low polarization dependence) is strongly desired. Since reducing the reflection at the upper surface of a grating is an important issue in order to realize high optical performance, we propose a novel grating with multi-layer structure in which a thin layer is used for decreasing the reflection from the surface. A good design, which provides high optical performance in the broad wavelength band, is successfully obtained.