Patent ID: 9031112
Filing Date: 2015-05-12
Classification: G02B,H01S,Y10T

Abstract:
1. An Echelle diffraction grating having a plurality of gratings, each of which has an asymmetrical triangular shape on a section in which the plurality of gratings are arranged, wherein each grating of the plurality of gratings includes a resin layer made of light curing resin and having a thickness between 2 μm and 10 μm, and a reflective coating layer formed on the resin layer, having a thickness between 120 nm and 500 nm, and made of aluminum, and wherein the each grating includes a blazed surface configured to receive and diffract incident light, wherein a blaze angle of the each grating that is an angle between the blazed surface of the each grating and a lattice plane is smaller than a first blaze angle that maximizes a diffraction efficiency of a blazed order of light diffracted by the plurality of gratings, wherein the blaze angle of the each grating has a second blaze angle as an initial value which is set so that an orientation ratio B/A that is a ratio between a diffraction efficiency A of the blazed order and a diffraction efficiency B of an order lower by one order than the blazed order can satisfy the following conditional expression: wherein light incident on the plurality of gratings is diffracted by the plurality of gratings on both the blazed order and the order lower by one order than the blazed order.