3 July 2003 Incoherent combining of 100-W Yb-fiber laser beams by PTR Bragg grating
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Proceedings Volume 4974, Advances in Fiber Lasers; (2003) https://doi.org/10.1117/12.501670
Event: High-Power Lasers and Applications, 2003, San Jose, CA, United States
Abstract
Volume diffractive gratings (Bragg gratings) in photo-thermo-refractive (PTR) inorganic glass are proposed for incoherent laser beam combining because they have narrow spectral selectivity and diffraction efficiency greater than 95% from visible to near IR regions. They showed no laser-induced damage, no thermal lens, and no Bragg angle shift under CW Yb-fiber laser (1096 nm) irradiation at 100 kW/cm2. It opens the way to rugged, low-cost, efficient optics for high-power laser systems. Based on theoretical modeling of PTR Bragg gratings, we have designed a high-efficient technology for incoherent combining of two or several laser beams with certain wavelength shift. Two 100 W beams of Yb-fiber lasers in the range of 1080-1100 nm with the wavelength separation of 11 nm were combined with efficiency exceeding 75% while material losses did not exceed 2-4%. No fading or parameter change of PTR Bragg grating working in two 100 W beams were found. It was found that the process limiting efficiency of incoherent beam combining is the spectral widening of radiation of Yb-doped fiber lasers. At high power, their spectral width exceeds spectral selectivity of Bragg grating and causes a decrease of diffraction efficiency.
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Igor V. Ciapurin, Leonid B. Glebov, Larissa N. Glebova, Vadim I. Smirnov, Eugeniu V. Rotari, "Incoherent combining of 100-W Yb-fiber laser beams by PTR Bragg grating", Proc. SPIE 4974, Advances in Fiber Lasers, (3 July 2003); doi: 10.1117/12.501670; https://doi.org/10.1117/12.501670
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