Yb:CALYO shaped crystal fibers: Growth and spectroscopic characterization

Abstract

Yb:CaYAlO4 (Yb:CALYO) shaped crystal fibers with different Yb3+ doping concentration were successfully grown by the micro-pulling-down (μ-PD) method. The effect of the Yb3+ concentration on the structure, absorption, emission and lifetime was systematically studied. The strongest absorption peaks of Yb:CALYO crystal fibers are located at 977 nm for σ and π polarization. The micro-photoluminescence indicate that Yb3+ ions in CALYO single crystal fiber grown by the μ-PD method distributed evenly across a cross-section. The emission cross-section of 5 at.% Yb:CALYO crystal fiber was calculated to be 0.86 × 10−20 and 1.08 × 10−20 cm2 at 983 nm for σ and π polarizations. Benefited from the disordered structrure of CaYAlO4 crystal, the full width at half maximum (FWHM) at 978 nm was 68.9 nm and 80.9 nm, respectively. The fluorescence lifetime of 2F5/2 energy level of Yb:CALYO crystal fibers with concentration of 0.5 at.%, 1 at.%, 2 at.% and 5 at.% was calculated to be 435 μs, 484 μs, 514 μs and 453 μs, respectively. The experimental results show that Yb:CALYO crystal fiber is a potential laser medium for ultrashort laser operation.