Transmission diffraction element

摘要

A transmitting diffraction element may include a transparent substrate, and a plurality of convex parts periodically formed on one surface of the transparent substrate, and be configured to diffract incident light to the transparent substrate. Each of the convex parts may include first, second, third, and fourth layers that are stacked on the transparent substrate. The first and third layers may be made of a material having a high refractive index, and the second and fourth layers may be made of a material having a low refractive index that is lower than the high refractive index.

主权项

1. A transmitting diffraction element comprising:
a transparent substrate; and a plurality of convex structures periodically formed on a surface of the transparent substrate, wherein the plurality of convex structures comprises a first layer stacked on the transparent substrate, a second layer stacked on the first layer, a third layer stacked on the second layer, and a fourth layer stacked on the third layer, the first layer and the third layer are made of a first material having a refractive index, the second layer and the fourth layer are made of a second material having a refractive index that is lower than the refractive index of the first material, the third layer has a thickness that is largest amongst thicknesses of the first, second, third and fourth layers, and a diffraction efficiency of a transmitted first-order diffracted light is not less than 98% for p-polarization and s-polarization in a wavelength range of 1525-1575 nm or 1570-1610 nm when (2λ/P−sin θ)>1 is satisfied such that a transmitted second-order or higher diffracted light is not generated, where λ is a wavelength of an incident light, P is a grating period of the plurality of convex structures, and θ is an incident angle of the incident light.