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

We studied the refractive index and dispersive properties of the tetragonal rare-earth calcium aluminates, CaLnAlO<sub>4</sub> (Ln=Gd or Y). Sellmeier equations were derived for the spectral range of 0.35-2.1 μm. The group velocity dispersion (GVD) in CaGdAlO<sub>4</sub> is positive at ∼1  μm, 95  fs<sup>2</sup>/mm and negative at ∼2  μm, -40  fs<sup>2</sup>/mm. The GVD values for CaYAlO<sub>4</sub> are similar. In addition, thermo-optic coefficients, dn/dT, and thermal coefficients of the optical path were determined for CaYAlO<sub>4</sub>. dn/dT is negative at ∼1  μm, dn<sub>o</sub>/dT=-7.8, and dn<sub>e</sub>/dT=-8.7×10<sup>-6</sup>  K<sup>-1</sup>. 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.

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