Polarization independent gratings based on overlying refractive index matching layers

The utility model discloses a polarization independent grating based on a covering refractive index matching layer, and relates to the field of optics. According to the grating, a reflecting film (2)and a grating functional layer (3) are sequentially plated on a fused quartz substrate (1). According to the grating structure provided by the utility model, the diffraction efficiency of a TE mode and a TM mode in a bandwidth range of 1050-1080nm under a Littrow angle incident condition is higher than 98.5%; the highest diffraction efficiency exceeds 99.5%, the preparation tolerance is higher than that of a common grating, and high-efficiency diffraction of polarization-independent incident light can be realized; in addition, holographic exposure and reactive ion etching can be combined for preparation. The refractive index matching layer prepared through atomic layer deposition can play a role in protecting the grating structure, the stability of the grating under the special working environment conditions of hi