Enabling ultra-broadband high-efficiency gratings for single-cycle infrared lasers

Trevor B. Chen; Paul S. Hsu

doi:10.1117/12.3032561

4 October 2024 Enabling ultra-broadband high-efficiency gratings for single-cycle infrared lasers

Trevor B. Chen, Paul S. Hsu

Author Affiliations +

Proceedings Volume 13116, Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XXI; 1311609 (2024) https://doi.org/10.1117/12.3032561
Event: Nanoscience + Engineering, 2024, San Diego, California, United States

Abstract

To generate the shortest high power laser pulse, a single-cycle pulse, gratings inside the ultrafast laser’s compressor and stretcher need to meet three requirements: high efficiency, ultra-broad bandwidth, and high damage threshold. These three requirements are especially difficult to meet for Infrared (IR) lasers. We have demonstrated for the first time that combination of E-beam lithography and anisotropic wet etching of silicon wafers can produce gratings meeting the three requirements. A global optimization approach is used to achieve diffraction efficiency > 90% for mid IR gratings centered at 5μm with a 65% relative bandwidth, which is 1.47x (2.1x) lager than required by Gaussian-shaped (sech²-shaped) single-cycle pulses. A similar high-efficiency mid-IR grating was recently fabricated and tested, demonstrating an efficiency of 92.0% at 4.3μm, which closely matches the designed efficiency of 94.5%. Conformal coatings in fabrication and large angle of incidence in design are employed to improve damage threshold. Further enhancement of the grating performance has been realized through a double-blazing feature, combining the classic triangular groove geometry with a “land-ridge” modulation. The design methodology has been applied to near IR and long IR successfully to prove that the new design approach and fabrication technology combined is a reliable way to make gratings for single-cycle high-power ultrafast laser for entire IR region (0.8μm – 20μm).

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Trevor B. Chen and Paul S. Hsu "Enabling ultra-broadband high-efficiency gratings for single-cycle infrared lasers", Proc. SPIE 13116, Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XXI, 1311609 (4 October 2024); https://doi.org/10.1117/12.3032561

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