Linearly to circularly polarized light with a 1D-rectangular grating

Circularly polarized light is generally generated by linearly polarized light passing through a quarter wave plate, which use the birefringence to generate phase difference. However, two beams of orthogonal linearly polarized light can also produce phase difference after being reflected by the grating. In this paper, two beams of orthogonally polarized light were incident on the one-dimensional grating, and the reflected diffracted light produced a phase difference. When the phase difference of π/2 is satisfied and the amplitudes of the two orthogonal polarized lights are equal, circularly polarized light can be obtained. In this way, multiple beams of circularly polarized light can be obtained, and a simple method for obtaining circularly polarized light has been developed. Adjusting the period, duty cycle and groove depth of the rectangular grating can change the phase of the reflected light. By finding suitable structural parameters, we can design a quarter wave plate grating that can obtain multiple beams of circularly polarized light at the same time. This is a kind of new optical delayed π/2 phase device.