The fluoride fiber laser with the longest emission wavelength, the Ho3+-transition at 3.9 μm in the attenuation minimum of the 3–5-μm atmospheric window, is characterized. After reviewing the importance of fluoride fibers due to their low phonon energies, we describe room-temperature fluorescence and laser action with liquid-nitrogen cooling. Continuous-wave laser action at 3.9 μm is presented for the 640- and the 890-nm pump ranges. A shift of the emission wavelength is achieved by varying the resonator mirrors. Laser characteristics and temperature dependence are discussed.
© 1997 Optical Society of America
Jutta Schneider, Carsten Carbonnier, and Udo B. Unrau, "Characterization of a Ho3+-doped fluoride fiber laser with a 3.9-μm emission wavelength," Appl. Opt. 36, 8595-8600 (1997)