Boundary Effects in the Diffraction of Light by Volume Gratings: II. Phase Transmission Gratings

摘要

The two-wave approximation of the method of characteristics modes is used to analyze theoretically the diffraction of light by volume phase transmission grating for arbitrary proportions between the average refractive index of the grating and the refractive indices of the ambient media. Simple expression are derived for calculating the amplitudes of the diffracted waves in the case where the angle of incidence of the primary wave coincides with the Bragg angle. The roles of the front and back boundaries of the grating are discussed separately, and a new method for separating the contribution of the boundary diffraction, which is due to the periodic inhomogeneity of the grating boundaries, is proposed. The experimental possibility of selecting partial Bloch waves in the measurements of the diffraction efficiency of gratings that have high reflection coefficients of both boundaries is demonstrated.