Improved laser efficiency by direct diode laser pumping of the radiation-resistant Nd:gadolinium–scandium–gallium garnet

Abstract

Spectroscopic investigation of the radiation-resistant Nd:GSGG crystals and ceramics reported in this paper evidences that the absorption line at 883 nm corresponding to the unusual situation of quasi-degenerate absorption transitions 4 I 9/2 (2) → 4 F 3/2 (1) and 4 I 9/2 (3) → 4 F 3/2 (2) can be used for efficient direct diode laser pumping of this material, with stable absorption over an extended temperature range. It is inferred that the reduction of the quantum defect at this wavelength of pump compared to the traditional 807 nm pumping could improve the laser parameters and reduce drastically the heat generation, leading to a considerable extension of the power scalability. This possibility is demonstrated for the first time in the case of the 1061 nm laser emission in a continuous-wave and in the repetitive active acousto-optic and passive Q-switched laser emission. In all regimes this manifests in the reduction of the laser threshold, increase of slope efficiency and extension of the average power range. Additionally, in the active Q-switching this enables increased pulse energy and reduced pulse duration. The direct pumping could revitalize the utilization of Nd:GSGG for construction of lasers with storage of population inversion or working in an ionizing radiation environment.

Red-diode-pumped Cr:Nd:GSGG laser: two-color mode-locked operation

“…The output powers obtained for each line and the wavelength of the transitions are in good agreement with the measured strength of emission cross-section values for the different transitions of the Nd ion in GSGG (Fig. 2, and [5,15]). Compared to earlier diode pumping results, the slope efficiencies obtained in this study are relatively low (22.6% in [5,15] versus 16% in this study for MMD diode pumping).…”

“…2, and [5,15]). Compared to earlier diode pumping results, the slope efficiencies obtained in this study are relatively low (22.6% in [5,15] versus 16% in this study for MMD diode pumping). We suspected that this fact is due to the higher passive losses of the Cr:Nd:GSGG crystal that we have at hand during this study.…”

“…Diode pumping enables construction of compact and lower-cost laser systems with improved electrical-to-optical conversion efficiency. Usually, sharp absorption peaks of Nd:GSSG around 808 or 883 nm are employed for pumping (see [4,14] for an absorption spectrum) [12][13][14][15][16]. On the other hand, besides improving efficiency in flashlamp or solar excitation, co-doping of Nd:GSGG with Cr ions also allows for red laser diodes as alternative pump sources [11].…”

Sol–gel synthesis, characterization and study of substitution effects in different gallium-containing garnets

“…The IR luminescence was observed in chromium-doped GGG, and yellow persistent luminescence was determined in ceriumand chromium-co-doped GGG [39,40]. Improved physical properties were also observed for differently doped gadolinium scandium gallium garnets (Gd 3 Sc 2 Ga 3 O 12 , GSGG) [41][42][43]. The results reported in several studies [44][45][46][47] indicated that transition metal-or lanthanide-doped lutetium gallium garnets (Lu 3 Ga 5 O 12 , LuGG) are promising new laser materials, and they are expected to be comparable to the most widely used compound, YAG.…”

Structure and temperature effects on Nd3+ spectra in polycrystalline mixed scandium aluminum garnets Y3Sc Al5−O12

“…R 2 (884.4 nm) are collected in a two-peaked absorption band centered at 885 nm, with integral absorption similar to that of the Z 1 ? R 2 band and with $3 nm FWHM for 1 at.% Nd [31][32][33]; for Nd:GSGG these two absorption lines are practically coincident [34]. Pumping the Nd:YAG at 885 nm reduces the quantum defect by $9.5% and the heat load parameter for the one-micron laser emission by $30% compared with 808 nm pumping [31][32][33].…”