Optical characterization and laser gain modeling of a NdAl3(BO3)(4) (NAB) microchip laser crystal

In this work a systematic optical characterization of the NdAl3(BO3)(4) (NA B) crystal has been carried out by means of spectroscopic measurements. The energy levels (118) of the Nd3+ constituent ions have been identified and labeled by appropriate crystal field quantum numbers (mu =1/2 or mu =3/2). Laser site selective experiments revealed the presence of two nonequivalent environments for the Nd3+ ions. From room temperature absorption and emiss ion spectra and using the Judd-Ofelt formalism the emission cross sections and quantum efficiency (eta =0.1) of the metastable state F-4(3/2) have bee n determined. By further modeling we have estimated the crystal length and output coupler transmittance which optimize laser efficiency of a diode pum ped NAB laser. The optimum crystal length found in all cases is around 100 mum. Finally, the high laser efficiencies predicted (up to 61% and 45% for laser oscillation at 1.06 and 1.34 mum, respectively) make NAB an excellent candidate to be incorporated in a diode pumped microchip laser device. (C) 2001 American Institute of Physics.