Diffraction efficiency sensitivity to oblique incident angle for multilayer diffractive optical elements

Abstract

The relationship between diffraction efficiency of multilayer diffractive optical elements (MLDOEs) and arbitrary incident angle was numerically analyzed with the effective area method. The method is based on the shield effect between two elements of MLDOEs; a generalized diffraction efficiency formulation was obtained in a wide range of tilt angles, which overcame the limitations of scalar diffraction theory when the period width of MLDOEs is taken into account. A detailed comparison of the proposed effective area method with the scalar diffraction theory is numerically presented for MLDOEs. The validity of the proposed method is verified by comparison with the rigorous electromagnetic analysis method, especially the finite-difference time-domain method. The analysis results show that the shield effect augments with the increase of the incident angles; the effect of incident angles on MLDOEs with finite period widths is more noticeable than that with large period widths.

Conditions for Minimizing the Computational Complexity of the RCWA Calculation of the Diffraction Efficiency of Sawtooth Two-Layer Double-Relief Microstructures

“…The search for optimal pairs of optical materials for the DOE microstructure on determining the optimal relief depths for each pair of optical materials; this multiple calculations of DE. As reported in [8], the results obtained based on the culated using the scalar effective area method (EAM) [9,10] are fairly reliable in th and calculation of microstructures intended for operation in the IR and visib [9,10]. This applies to a greater extent to selecting the optimal pairs of optical m but to a lesser extent to assessing the optimal depths of the reliefs and to asses achievable DE.…”

Direct search method of double-layer diffractive optical elements

“…The relationship between the diffraction efficiency and the incident angle of a multilayer diffractive optical element with a finite period width can be expressed as 27 ηeamk={sinc2false(m−ϕfalse)·sinc22ex(t1T2ex)sinc22ex(t2T2ex)sinc22ex(t3T2ex)sinc22ex(t4T2ex)false(θ1≤0false)sinc2false(m−ϕfalse)·3ex[cosfalse(θ0false)+cosfalse(θ1false)23ex]2·3ex[cosfalse(θ1false)+cosfalse(θ2false)23ex]2false(θ1>0false),which m…”

Multilayer diffractive optical element material selection method based on transmission, total internal reflection, and thickness

“…1. Ray propagation inside an MLDOE for off-axis incident angle [12]. The continuous surfaces of each layer are modeled with an N-step profile instead.…”

“…On the other hand, off-axis incidence studies [9][10][11] have shown that an increase of the incident angle results in a loss of diffraction efficiency, which depends on the material combination. A widely used material selection method (MSM) [12] is based on the following observation: an "optimal" MLDOE design should undergo the smallest diffraction efficiency drop for the highest incidence angle. Although this method is fast and gives useful results, its applicability is limited by the validity domain of the TEA.…”