Diode-pumped self-frequency-doubling Nd:GdCa_4O(BO_3)_3 lasers: toward green microchip lasers

An output power of 115 mW at 545 nm has been obtained from a diode-pumped self-frequency doubling $\mathrm{Nd}:{\mathrm{GdCa}}_4\mathrm{O}({\mathrm{BO}}_3{)}_3$ laser in a stable cavity. The infrared emission of the laser was found to be 1091 nm, not the 1060 nm that was expected when the highest line of the fluorescence spectrum was considered. We have demonstrated that the emission at 1091 nm was caused by the temperature increase at the focus of the pump beam. We demonstrated also, for what we believe was the first time, lasing operation of Nd:GdCOB in a plano–plano cavity and obtained an output power of 22 mW at 545 nm. To our knowledge, this is the highest output power ever reported with a self-frequency-doubling crystal in a plano–plano cavity.