Spectroscopy and cw laser action, magnetooptics and nonlinear optical frequency conversion in Ln(3+) doped and undoped Bi4Ge3O12 and Bi4Si3O12 crystals

摘要

Detailed spectroscopic, stimulated emission (SE), and chi ((2))- and chi ((3))- nonlinear optical properties of cubic piezoelectric Bi4Ge3O12 and Bi4Si3O12 Compounds undoped and doped with trivalent lanthanides (Ln(3+)) were investigated. Particular attention was paid to bismuth germanate crystals doped with Nd3+ ions. Their absorption and luminescence intensity characteristics, including the spectroscopic quality parameter X-Nd, peak and effective cross sections for inter-Stark laser transitions of the F-4(3/2) --> I-4(11/2) and F-4(3/2) --> I-4(13/2) channels, were determined. Continuous-wave (cw) laser action into two near-infrared intermanifold transitions F-4(3/2) --> I-4(11/2) and F-4(3/2) --> I-4(13/2) this crystal with GaAlAs-laser-diode pumping was achieved. Magnetooptical polarization effects have been studied. For the first time, also pulsed laser action of Tm3+ and Yb3+ ions in Bi4Ge3O12 with Xe-flashlamp excitation was obtained. All the observed SE transitions for Nd3+ and Yb3+ ions in bismuth germanate were identified. Nonlinear chi ((2))- and chi ((3))-effects in acentric Bi4Ge3O12 and Bi4Si3O12 crystals as a high-order stimulated Raman scattering (SRS), second harmonic generation (SHG), and sum-frequency generation of the pump and SRS beams produced by picosecond Nd3+:Y3Al5O12 laser excitation were investigated. All observed multiple Stokes and anti-Stokes (up to 40-th order) components were analyzed and attributed to the translation T ' (Bi3+) vibration modes of these crystals. The room-temperature (RT) steady-state Raman gain coefficients for these new chi ((3))-active media were estimated to approximate to0.8 cm GW(-1). Therefore, we classify the undoped and Ln(3+)-ions doped Bi4Ge3O12 and Bi4Si3O12 crystals as a promising materials for multifunctional optical laser devices, including self-SRS laser shifters. [References: 71]