Interconfigurational two-photon transitions in Nd^3+:Y_3Al_5O_12

Abstract
Resonantly enhanced, near-ultraviolet 4f3 → 4f25d two-photon transitions have been observed in trivalent neodymium-doped yttrium aluminum garnet (Nd3+:Y3Al5O12). The two-photon excitation spectra over the 40 400–46 730 cm−1 transition energy range are characterized by sharp resonance peaks on a slowly varying background caused by nonresonant transitions. The peak two-photon cross section involving the 2P1/2 resonant intermediate state is 9 × 10−51 cm4 s, and the integrated cross section is 2.2 × 10−38 cm4.