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

Loiko, P. and Yoon, S.J. and Serres, J.M. and Mateos, X and Beecher, S.J. and Birch, R.B. and Savitski, V.G. and Kemp, A.J. and Yumashev, K. and Griebner, U. and Petrov, V. and Aguiló, M. and Diaz, F. and Mackenzie, J.I. (2016) Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2. Optical Materials, 58. pp. 365-372. ISSN 0925-3467 (https://doi.org/10.1016/j.optmat.2016.06.005)

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Abstract

High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77–450 K. At room-temperature, the maximum stimulated emission cross-section is σSE = 21.4 × 10−20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ 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 cm3/s. When cut along the Ng 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.

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