Simply structured polarization-independent high efficiency multilayer dielectric gratings

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Diffraction gratings are essential optical components.
• Achieving high diffraction efficiency and polarization independence simultaneously is challenging.
• Thermal stability under high laser power is critical for practical applications.

Purpose of the Study:

• To design and fabricate a polarization-independent multilayer dielectric diffraction grating.
• To achieve a low aspect ratio and high diffraction efficiency.
• To evaluate the thermal stability of the fabricated grating.

Main Methods:

• Design and simulation of a multilayer dielectric diffraction grating.
• Fabrication using ion-assisted deposition and reactive ion etching.
• Characterization of diffraction efficiency, polarization independence, and thermal stability under laser irradiation.

Main Results:

• The designed grating exhibited a low aspect ratio (0.59) and high polarization-independent diffraction efficiency (97.2%) in the 1030-1080 nm range.
• The fabricated grating achieved a mean polarization-independent diffraction efficiency of 96.1% with a low standard deviation (0.68%).
• Heat treatment at 400°C reduced the temperature variation under high laser power density from 8.8°C to 2.3°C.

Conclusions:

• A polarization-independent multilayer dielectric diffraction grating with excellent performance was successfully designed and fabricated.
• The grating demonstrates high diffraction efficiency and low aspect ratio, suitable for demanding optical systems.
• Heat treatment significantly enhances the thermal stability of the diffraction grating, enabling its use in high-power laser applications.