Study on phase and amplitude modulation of a two-dimensional subwavelength diffractive optical element on artificial distributed- index medium

摘要

In this paper, we investigate the characteristics of the binary lamellar grating having the period smaller than the wavelength of the incident light and propose the structure of a novel binary subwavelength diffractive optical element (SWDOE). The effective medium theory and the birefringence multi-layer analysis method are used to analyze the proposed DOE structure. It is shown that the polarization sensitivity of the subwavelength scale lamellar grating can be used to design the SWDOE that can modulate both the phase and the amplitude of the incident light In view of the synthesis of DOE, that is, the nonlinear optimization, the amplitude modulation means the extension of the degree of freedom for the design of DOE. So the relation between the phase and the amplitude modulation is derived through the numerical analysis.