Spectroscopic bases for performance enhancement and power scaling of Nd: GSGG lasers

(Cr, Nd)-doped Gd₃Sc₂Ga₃O₁₂ garnet (GSGG) gained popularity owing to its good laser performances in Q-switched regime under lamp pumping based on two circumstances: (i) good absorption of Cr³⁺ ions and very efficient energy transfer to Nd³⁺, and (ii) better performance in Q-switched emission than Nd: YAG due to longer lifetime, weaker self-quenching of emission and smaller emission cross-section. GSGG shows better stability than YAG at ionizing radiation and single crystals of large size can be grown by Czochralski method, with uniformity and reproducibility problems. However, power scaling of these lasers was hampered by the weaker heat conductivity, about half from Nd: YAG and with the advent of diode lasers for Nd³⁺, GSGG lost its popularity. The present work investigates the spectroscopic properties of Nd-doped GSGG in order to identify modalities to extend the power range by increasing the emission performances and reduction of heat generation.