Polarization Split Element and Production Method Thereof, and Optical Pickup, Optical Device, Optical Isolator and Polarizing Hologram Provided with the Polarization Split Element

摘要

A polarization split element 1 includes a substrate 2 and a plurality of ridge-shaped convex portions 3 provided in parallel with one another at equal intervals on the substrate 2, and performs polarization splitting with respect to light beams 4 incident to the plurality of the convex portions 3 by diffraction. This polarization split element 1 satisfies a conditional expression represented by: 1.6<=n<=2.2 and 0.6<=P/lambda<=0.8, where n denotes a refractive index of the convex portion 3 with respect to the incident light beam 4, P denotes a grating period that is a sum of the interval between the adjacent convex portions 3 and a width of the convex portion 3, and lambda denotes a wavelength of the incident light beam 4, and splits the incident light beams 4 into: a TM polarization zeroth-order diffracted light beam whose magnetic field has a vibration direction that is the same as a length direction of the convex portion 3; and a TE polarization first-order diffracted light beam whose electric field has a vibration direction that is the same as a length direction of the convex portion 3. According to the configuration of this polarization split element 1, it is possible to provide a polarization split element that can decrease a grating height and an aspect ratio while maintaining its high performance.