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Rectangular multilayer dielectric gratings with broadband high diffraction efficiency and enhanced laser damage
Optics Express
|March 17, 2021
Summary
Researchers developed novel multilayer dielectric gratings (MDGs) using advanced fabrication. These gratings exhibit a high laser-induced damage threshold and broadband efficiency, crucial for laser applications.
Area of Science:
- Optics and Photonics
- Materials Science
- Nanotechnology
Background:
- Multilayer dielectric gratings (MDGs) are essential optical components.
- Improving laser-induced damage threshold (LIDT) and broadband efficiency is critical for high-power laser systems.
Purpose of the Study:
- To fabricate broadband multilayer dielectric gratings (MDGs) with a rectangular Hafnium dioxide (HfO2) profile.
- To mitigate laser-induced damage at the grating ridge.
- To achieve high diffraction efficiency over a broad spectral range.
Main Methods:
- Utilized a novel fabrication process combining laser interference lithography, nanoimprint, atomic layer deposition, and reactive ion-beam etching.
- Investigated the electric-field intensity (EFI) enhancement within different grating profiles.
- Developed an etching process to avoid nano-absorbing defects.
Main Results:
- Successfully fabricated broadband MDGs with a rectangular HfO2 grating profile.
- Achieved a high laser-induced damage threshold (LIDT) of 0.59 J/cm² for 40 fs Ti-sapphire laser pulses.
- Demonstrated excellent broadband diffraction with 95% efficiency over 150 nm in TE polarization.
Conclusions:
- The rectangular grating profile minimizes EFI enhancement, reducing laser damage.
- The novel fabrication process avoids nano-absorbing defects, further enhancing LIDT.
- These MDGs offer superior performance for high-power laser applications.
