Preparation and spectroscopic characteristics of Tm:YPO4 crystal

Tetragonal Tm3+:YPO4 single crystals were successfully grown by high temperature solution method. The crystal growth, structures and detailed spectroscopic properties including polarized absorption spectra, FT-IR and Raman spectra, polarized fluorescence spectra and lifetime were reported for the first time. The bandwidth of absorption band around 800 nm were determined to be 13.1 nm for pi-polarization and 22.5 nm for sigma-polari-zation, indicating that Tm3+:YPO4 crystal is suitable for commercial AlGaAs laser diodes pumping. Spectroscopic parameters, including J-O intensity, oscillator strength, line strength, fluorescence branching ratios, spontaneous transition rates and radiative lifetime were analysed by J-O theory. The continuous positive gain range can reach 270 nm when the excited state ion fraction beta >= 0.5, showing the promising applications in tunable and ultrafast laser. The results indicate that Tm3+:YPO4 crystal is a potential laser medium which is expected to realize at around 1.9 mu m.