We present a continuously tunable thulium(Tm)-doped fiber laser operating in the important 2.1 μm region, which is tandem-pumped by another Tm-doped fiber laser at 1908 nm. The advantages of pumping a Tm-doped fiber laser at the long-wavelength absorption tail (>1900 nm) of the fiber include a reduced quantum-defect, and efficient suppression of the amplified spontaneous noise (and potential parasitic lasing) at the short-wavelength region. This facilitates attainment of stable lasing operation in the long-wave emission tail of the Tm fiber at ~2.1 μm. By rotating a diffraction grating inside the Tm fiber laser cavity, we experimentally achieved a wavelength-tuning range of 2000-2172 nm. At central wavelengths of 2050 nm, 2150 nm, and 2172 nm, the slope efficiencies were 23%, 16%, and 9.9%, respectively. To the best of our knowledge, this is the first demonstration of long-wavelength operation of a Tm fiber laser system tandem-pumped at >1900 nm.
Bibliographical note© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Liu, F., Liu, P., Feng, X., Wang, C., Yan, Z., & Zhang, Z. (2019). Tandem-pumped, tunable thulium-doped fiber laser in 21 μm wavelength region. Optics Express, 27(6), 8283-8290. https://doi.org/10.1364/OE.27.008283