High-power continuous-wave Tm 3+ :Ho 3+ -codoped fiber laser operation from 2.1 µm to 2.2 µm

• Published in: Optics letters 2022-05, Vol.47 (10), p.2542
• Main Authors: Forster, Patrick, Romano, Clément, Schneider, Julian, Eichhorn, Marc, Kieleck, Christelle
• Format: Article
• Language: English
• ISSN: 0146-9592; 1539-4794
• DOI: 10.1364/OL.458921

A Tm :Ho -codoped free-space single-oscillator fiber laser is under investigation with special focus on the power scalability of emission wavelengths from 2.1 µm to 2.2 µm. Using a tunable diffraction grating, a 200-nm tunable laser source is built. Laser output powers above 10 W are delivered from 1990 nm up to 2190 nm, demonstrating the range for stable high-power laser operation. By replacing the diffraction grating by a highly reflective, narrow linewidth volume Bragg grating, power scaling is performed at 2.1 µm and is even enabled at a wavelength of 2.2 µm. Using a volume Bragg grating (VBG) at 2.1 µm, a slope efficiency of 49% is measured with an output power of 262 W. Using another VBG with a center wavelength of 2.2 µm, the fiber laser delivers a record power of 77 W with a slope efficiency of 29%.