Sellmeier equations, group velocity dispersion, and thermo-optic dispersion formulas for CaLnAlO₄ (Ln = Y, Gd) laser...

We studied the refractive index and dispersive properties of the tetragonal rare-earth calcium aluminates, CaLnAlO₄ (Ln=Gd or Y). Sellmeier equations were derived for the spectral range of 0.35-2.1 μm. The group velocity dispersion (GVD) in CaGdAlO₄ is positive at ∼1  μm, 95  fs²/mm and negative at ∼2  μm, -40  fs²/mm. The GVD values for CaYAlO₄ are similar. In addition, thermo-optic coefficients, dn/dT, and thermal coefficients of the optical path were determined for CaYAlO₄. dn/dT is negative at ∼1  μm, dn_o/dT=-7.8, and dn_e/dT=-8.7×10^-6  K^-1. Thermo-optic dispersion formulas were constructed. The obtained data are of key importance to the design of high-power mode-locked oscillators at ∼1 and ∼2  μm based on such laser hosts.