Fabrication and analysis of a three-layer stratified volume diffractive optical element high-efficiency grating

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Volume holographic gratings offer high efficiency but are complex to fabricate.
• Stratified Volume Diffractive Optical Elements (SVDOEs) provide an alternative approach to emulate volume gratings.
• Existing methods for fabricating SVDOEs face challenges in achieving precise layer alignment.

Purpose of the Study:

• To demonstrate a high-efficiency (>80%) three-layer Stratified Volume Diffractive Optical Element (SVDOE).
• To validate simulation accuracy using rigorous coupled wave analysis (RCWA).
• To explore the potential for increased efficiency with more layers.

Main Methods:

• Fabrication of a three-layer SVDOE using binary grating layers interleaved with SU-8 homogeneous layers.
• Development and implementation of a high-precision alignment technique using a contact mask aligner.
• Optical measurement of angular sensitivity and comparison with RCWA simulations.

Main Results:

• Achieved a grating efficiency exceeding 80%.
• Experimental results showed excellent agreement with RCWA simulations.
• Simulations predicted higher efficiencies with an increased number of layers.

Conclusions:

• The demonstrated SVDOE design achieves high efficiency and accurate angular control.
• The developed alignment technique is crucial for fabricating complex layered diffractive optics.
• SVDOEs offer a promising platform for advanced optical applications requiring tailored angular responses.