9-13 July 2012
Wavelength Selected, Tm:YLF Slab Pump-Source
Presented by Dr. Hencharl STRAUSS on 13 Jul 2012 from 08:20 to 08:40
Type: Oral Presentation
Track: Track C - Photonics
1.9 µm Tm:YLF slab lasers are used to pump high energy Ho:YLF slab amplifiers  as well as for applications in medicine and defense. We have previously demonstrated high average powers (~200 W) from such a system at ~1.9 µm. However, efficient pumping of Ho:YLF requires that the Tm:YLF output wavelength reasonably well match one of Ho:YLF’s two strong absorption peaks at either 1890 nm or 1940 nm. This is usually accomplished by polarization and output-coupler selection using threshold calculations. Volume Bragg Grating (VBG) mirrors offer a more precise and sure way to select a specific wavelength. A VBG mirror has a periodic variation of the refractive index and is transparent at most wavelengths. It has a high reflectivity at a certain wavelength which fulfills the Bragg condition (in this case 1890 nm). We used a VBG as a back-reflector in a Tm:YLF slab laser. The slab crystal was pumped with a 300 W, 792 nm diode stack using a pump reproducing scheme. It delivered over 80 W of output power at 1890 nm and had a good beam quality compared to other slab laser systems. We also report on initial results of this system pumping a 60 mm Ho:YLF crystal laser. The results indicate that the technology shows great promise for wavelength selection and stabilization of other crystal and fibre laser systems.