Optical absorption and stimulated emission of neodymium in yttrium orthosilicate

A spectroscopic investigation of the biaxial crystal yttrium orthosilicate doped with Nd³⁺(Nd³⁺:Y₂SiO₅) has been performed. Spectrally and orientationally resolved emission cross sections necessary for the evaluation of laser performance on the Nd^{3+ 4}F_3/2-⁴I _9/2 and ⁴F_3/2-⁴I_11/2 transitions have been determined. The Judd-Ofelt theory has been applied to measured values of optical absorption line strengths to obtain the orientation averaged intensity parameters: Ω₂-3.34×10^-20 cm², Ω ₄=4.35×10^-20 cm², and Ω₆=5.60×10^-20 cm². These Judd-Ofelt intensity parameter values are significantly different from those previously reported by A.M. Tkachuk et al. Using these intensity parameters, the Nd^{3+ 4}F₂ metastable state lifetime is predicted to be 225 μs. Measured low Nd concentration ⁴F_3/2 lifetimes of 214 μs indicate a high radiative quantum efficiency. Because of the Stark level splitting of the Nd^{3+ 4}F_3/2 and ⁴I_9/2 manifolds, laser operation at twice one of the Cs atomic resonance filter acceptance wavelengths is possible