An efficient actively Q-switched Tm³⁺-doped single-oscillator fiber laser based on a silica polarization-maintaining (PM) double-clad fiber provided average powers of 23 W at pulse widths of 65 ns at 40 kHz pulse repetition frequency. It was used to directly pump a ZnGeP₂ optical parametric oscillator (OPO). Up to 6.5 W were generated in mid-IR wavelength range.

A diode-pumped, actively mode-locked high-power thulium (Tm³⁺)-doped double-clad silica fiber laser is demonstrated, providing an average output power in mode-locked (continuous wave) operation of 53 W (72 W) with a slope efficiency of 34% (38%). Mode-locking in the 6th-harmonic order was obtained by an acousto-optic modulator driven at 66 MHz without dispersion compensation. The shortest measured output pulse width was 200 ps. Owing to a diffraction grating as cavity end mirror, the central wavelength could be tuned from 1.95 to 2.13 μm. The measured beam quality in mode-locked and continuous wave operation has been close to the diffraction limit.

We report on Tm:YLF and Tm:LLF slab lasers (1.5 x 11 x 20 mm) end pumped from one end with a high-brightness 792 nm laser diode stack. These two lasers are compared under identical pump conditions in continuous-wave regime. A stronger negative thermal lens in Tm:LLF than in Tm:YLF is highlighted, making it more difficult to operate the Tm:LLF laser under stable lasing conditions. In a configuration where the high reflectivity cavity mirror has a radius of curvature of r = 150 mm, the Tm:YLF (Tm:LLF) laser produces a maximum output power of 150 W (143 W) for 428 W of incident pump power (respectively). For a second cavity configuration where the high reflectivity cavity mirror has a radius of curvature of r = 500 mm, the Tm:YLF laser produces a maximum output power of 164 W for 412 W of incident pump power and a 57% slope efficiency with respect to the absorbed pump power. The emitted wavelength of these two lasers are measured as a function of the output coupler reflectivity and it shows that Tm:LLF laser emits at a longer wavelength than Tm:YLF.

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We report on an Ho³⁺:InF₃ glass laser pumped by a Cr³⁺:LiSAF laser emitting at 889 nm. Ho³⁺:InF₃ glass is a promising material for direct mid-infrared lasers around 4 μm. To evaluate the performances of this new material, we compared it to an Ho³⁺:BYF crystalline laser pumped by the same source. At 650 mJ pump energy, 7.2 mJ (46 mJ) was obtained with Ho³⁺:InF₃ (Ho³⁺:BYF), respectively. This is, to the best of our knowledge, the first reported laser activity in this type of glass.