Sellmeier equations, group velocity dispersion, and thermo-optic dispersion formulas for CaLnAlO 4 (Ln = Y, Gd) laser host crystals

We studied the refractive index and dispersive properties of the tetragonal rare-earth calcium aluminates, CaLnAlO (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 is positive at ∼1 μm, 95 fs /mm and negative at ∼2 μm, -40 fs /mm. The GVD values for CaYAlO are similar. In addition, thermo-optic coefficients, dn/dT, and thermal coefficients of the optical path were determined for CaYAlO . dn/dT is negative at ∼1 μm, dn /dT=-7.8, and dn /dT=-8.7×10 K . 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.