Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2.

High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO 4 ) 2 (Nd:KGW) laser crystals in the temperature range 77–450 K. At room-temperature, the maximum stimulated emission cross-section is σ SE = 21.4 × 10 −20 cm 2 at 1067.3 nm, for light polarization E || N m . The lifetime of the 4 F 3/2 state of Nd 3+ in KGW is practically temperature independent at 115 ± 5 μs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ∼2.5 × 10 −17 cm 3 /s. When cut along the N g optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ∼4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 μm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated. [ABSTRACT FROM AUTHOR]