Characterization of a Ho^3+-doped fluoride fiber laser with a 39-μm emission wavelength

Abstract

The fluoride fiber laser with the longest emission wavelength, the Ho(3+)-transition at 3.9 mum in the attenuation minimum of the 3-5-mum 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 mum 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.

High-Power ZBLAN Glass Fiber Lasers: Review and Prospect

“…The output is about 1 mW and the slope efficiency is 1.5%. Shortly after an 11 mW output was achieved with an optimization of the mirror design and the fiber [54]. However, in order to achieve efficient CW 3.9 μm emission, the fiber has to cool down to 77 K because the multiphonon rate increases strongly for temperature above 100 K and for wavelengths above 3 μm.…”

Low phonon energy, Nd:LaF/sub 3/ channel waveguide lasers fabricated by molecular beam epitaxy

“…Incorporating the fluoride host in an optical waveguide geometry can also offer low thresholds and high efficiencies, increasing the potential for continuous wave (CW) operation at room temperature and at relatively high power levels. This has been demonstrated most effectively with ZBLAN optical fibers [3]- [5].…”

High-power diode-pumped fiber laser operating at 3 μm

“…Traditionally, research into fiber lasers using fluoride glasses operating in the far shortwave region of the spectrum has been driven by requirements in medicine and materials processing; however, as demands develop from mid-IR photonics, pushing the emission wavelength of fiber lasers further into the mid-IR is desirable. To date, the rare earth ions erbium [2], holmium [3], and dysprosium [4] have created the highest output power and efficiency in the far shortwave IR region with the former two ions also generating low power emission in the near mid-IR region albeit at low efficiencies [5][6][7]. A recent report [8] of an all-fiber erbium-doped ZBLAN 2:825 μm fiber laser emitting 20:6 W of single transverse mode output power demonstrates the maturity and utility of fluoride glass fiber lasers for long wavelength emission.…”

“…Previous demonstrations of mid-IR emission from Ho 3þ -doped ZBLAN fibers lasers at 3:22 μm [5] and 3:95 μm [6] used high lying fluorescence transitions which resulted in low <3% slope efficiencies and considerable heating of the fiber. The use of lower lying transitions accessible using diode pumping and laser transition cascading offers an effective route to lowering the rates of multiphonon decay and to the production of efficient mid-IR light.…”