Crystal growth and properties of the disordered crystal Yb:SrLaAlO4: a promising candidate for high-power ultrashort pulse lasers

Abstract

A high quality Yb³⁺-doped strontium lanthanum aluminate crystal, Yb:SrLaAlO₄ (Yb:SLA) is grown by the Czochralski method. It is tetragonal (sp. gr. I4/mmm, a = b = 3.7536 Å, c = 12.6253 Å). Room- and low-temperature spectroscopy of Yb³⁺ ions in this crystal are studied. The Stark splitting is resolved. Absorption, stimulated-emission (SE) and gain cross-sections are determined with polarized light. In the spectral range of laser emission, the maximum σ_SE is 0.57 × 10⁻²⁰ cm² at 1047 nm for σ polarization. The polarized Raman spectra of Yb:SLA are presented. Thermal properties of Yb:SLA are characterized in terms of the linear thermal expansion, specific heat and thermal conductivity. The latter is as high as 6.06 and 4.30 W m⁻¹ K⁻¹ along the a- and c-axes, respectively (at room temperature). Broadband tuning of a continuous-wave (CW) Yb:SLA laser, from 1011 to 1082 nm has been achieved. Due to its good thermal properties, broad and smooth gain spectra, Yb:LSA is a promising material for power-scalable, broadly tunable CW and sub-100 fs mode-locked lasers at ∼1 μm.