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The laser is nearing completion with demonstration of 73% frequency-conversion efficiency, deformable mirror operation that generated a 4-times diffraction limited spot, and commissioning of an advanced front end to be installed on the main laser.

We report initial operation of the Mercury laser with seven 4 x 6 cm S-FAP amplifier slabs pumped by four 80 kW diode arrays. The system produced up to 33.5 J single shot, 23.5 J at 5 Hz, and 10 J at 10 Hz for 20 minute runs at 1047 nm. During the initial campaign, more than 2.8 x 104 shots were accumulated on the system. The beam quality of the system was measured to be 2.8 x 6.3 times diffraction limited at 110 W of output, with 96% of the energy in a 5X diffraction limited spot. Static wavefront glass plates were used to correct for the low order distortions in the slabs due to fabrication and thermal loading. Scaling of crystal grown has begun with the first full size slab produced from large diameter growth. Using an energetics optimization code we find the beam aperture is scalable up to 20 x 30 cm and 4.2 kJ.

Single crystals of three Nd3+-doped disordered oxides have been grown and characterized as candidates for improved diode-pumped solid state lasers. These hosts include one melilite, SrGdGa3O7 (SGGM), and two gallogermanates, La3Ga5GeO14 (LGG) and its isomorph La3Ga5SiO14 (LGS). Spectroscopic properties such as absorption and emission bandwidth, fluorescent lifetimes, and emission cross-sections are included. Laser properties of the 4F3/2 - 4I11/2 transition at 1.06 microns have been measured.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The interest in diode pumped solid state lasers in the 2 μm region in recent years has been well documented. The need for compact, highly efficient sources has led to the study of new laser hosts which may improve performance. We have grown and analyzed the spectroscopic properties of two Tm3+-doped silicate oxyapatite hosts and one orthosilicate. These hosts are CaY4(SiO4)3O [CaYSOAP], CaLa4(SiO4)3O [CaLaSOAP], and Y2SiO5 [YSO or YOS]. The spectroscopic properties of these new hosts are compared with those of Tm3+:YAG, and indicate that these hosts may offer improvements to Tm3+:YAG in increasing tunability in the 2 μm region and in improving laser performance for the 2.3 μm transition. Preliminary laser results of a Tm:CaYSOAP laser are also presented.

Single crystals of Nd(3+):SrGdGa3O7 (SGGM) have been grown and characterized as candidate crystals for improved diode pumped lasers. The width of the 809 nm absorption in this disordered oxide crystal is 8 nm FWHM. The fluorescence lifetime of the 4F3/2 - 4I11/2 transition at 1.06 micron is 245 microsec. Dopant levels of 4 percent Nd have been achieved while maintaining high optical quality material.

Continuous-wave laser emission at 1.94 μm is reported in Tm:CaY4(SiO4)3O at room temperature with Ti:sapphire laser pumping at 790 nm. Pump thresholds of 100 mW and slope efficiencies of 32% have been achieved. The 3H6–3H4 pump absorption peak of 6% Tm:CaY4(SiO4)3O is six times stronger than the 3H6–3H4 pump absorption peak of 6% Tm:YAG.