Growth, polarized spectroscopy and high-performance laser operation of a novel mixed Tm:CaY0.9Lu0.1AlO4 crystal

Abstract

Tm3+-doped CaY0.9Lu0.1AlO4 single crystal was successfully grown by the Czochralski method. The crystal structure, polarized absorption spectra and polarized emission spectra of Tm:CaY0.9Lu0.1AlO4 crystals were investigated. By using the Judd–Ofelt approach, the intensity parameters Ω2,4,6, spontaneous transition rate, branching ratios and radiative lifetimes were calculated. Diode-end-pumped continuous-wave Tm:CaY0.9Lu0.1AlO4 lasers have also been investigated by establishing a simple and compact plane-concave cavity with four differently coated output couplers. Four different lasing wavelengths at about 2029 nm, 2000 nm, 1966 nm and 1888 nm have been achieved with maximum output power and slope efficiency of (1.98 W, 15.1%), (5.89 W, 46.2%), (6.92 W, 54.9%) and (5.54 W, 44.7%), respectively. The results in regard to the broad emission spectra and good laser performance show that the Tm:CaY0.9Lu0.1AlO4 mixed crystal could be very promising for broadband tunable and/or femtosecond ultrafast laser generation in the important 2-μm spectral region.