Spectroscopic characterization of Tm:CaYAlO4 shaped crystal fibers grown by the micro-pulling-down method

Tm3+-doped CaYAlO4 (Tm:CALYO) shaped crystals fibers with various doping concentration of 2 at.%, 3 at.%, 5 at.% and 7 at.% have been successfully grown by the micro-pulling-down (mu-PD) method. The polarized ab-sorption spectra, polarized fluorescence spectra and fluorescence decay curves were analyzed at room temper-ature. The absorption bands of 3H6 -> 3H4 transition centered at around 800 nm match well with commercial AlGaAs laser diode pumping sources. For 7 at.% Tm:CALYO crystal fiber, the full width at half maximum (FWHM) of the emission band for pi polarization at 1806 nm was 225.4 nm. The fluorescence of 3F4 level decreased strongly as the thulium concentration increased. All the results indicate that Tm:CALYO crystal fibers are promising for ultrashort and tunable laser operation.