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Proceedings Paper

Fabrication of high-efficiency, multilayer-dielectric, spectral-beam-combining gratings
Author(s): Siyi Tang; Lijang Zeng; Lifeng Li
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Paper Abstract

Spectral beam combining is an effective method to increase the total output power of a laser system while maintaining a high beam quality. The diffraction grating with high diffraction efficiency and high laser damage threshold is the key component in a spectral-beam-combining laser system. To meet the above requirements, we design a grating on top of a high-reflectivity HfO2/SiO2 thin-film stack. The diffraction efficiency of the grating depends mainly on the duty cycle and depth of the grating grooves. The grating was fabricated by using optical interference lithography and reactive ion beam etching. To achieve high efficiency, we controlled the duty cycle by applying an end-point detection technique during development and we controlled the groove depth by adjusting the ion-beam etching time length. In a 50 mm × 50 mm fabricated grating area, the measured diffraction efficiency in TE polarization was 95.8 ± 1.1 % at the center wavelength of 1030 nm. In the wavelength range of 1025 nm to 1035 nm, the measured average diffraction efficiency in TE polarization was 97.7% at center of the grating sample. We describe the details of our work, including design parameters, fabrication processes, and measured diffraction efficiencies.

Paper Details

Date Published: 18 November 2019
PDF: 7 pages
Proc. SPIE 11188, Holography, Diffractive Optics, and Applications IX, 111881X (18 November 2019); doi: 10.1117/12.2537584
Show Author Affiliations
Siyi Tang, Tsinghua Univ. (China)
Lijang Zeng, Tsinghua Univ. (China)
Lifeng Li, Tsinghua Univ. (China)

Published in SPIE Proceedings Vol. 11188:
Holography, Diffractive Optics, and Applications IX
Yunlong Sheng; Changhe Zhou; Liangcai Cao, Editor(s)

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