Auto-collimation diffraction of two-dimensional metal-dielectric grating with azimuth angle of 45°

Area of Science:

• Optics and Photonics
• Nanotechnology
• Materials Science

Background:

• High diffraction efficiency gratings are vital for optical systems.
• Existing gratings often struggle with polarization independence.
• Applications include displacement measurement and spectral beam combining.

Purpose of the Study:

• To propose and demonstrate a novel reflective two-dimensional metal-dielectric grating.
• To achieve polarization-independent high diffraction efficiency in an auto-collimation configuration.
• To explore its potential in advanced optical systems.

Main Methods:

• Design of a reflective two-dimensional metal-dielectric grating.
• Optimization of the grating structure for specific diffraction orders.
• Simulation and experimental fabrication of the proposed grating.
• Characterization of diffraction efficiency for TE and TM polarizations.

Main Results:

• The (-1, -1) diffraction order is diffracted back along the input light direction at a 45° incident azimuth angle.
• Optimized structure achieved 95.01% (TE) and 95.04% (TM) diffraction efficiencies at 632 nm.
• The cone frustum-based structure exhibits good manufacturing tolerance.
• Experimental fabrication and validation of the grating performance.

Conclusions:

• The proposed grating offers excellent polarization-independent diffraction efficiency.
• Its design is suitable for practical applications due to manufacturing tolerance.
• Significant potential for 2D displacement measurement and high-power laser systems.