Mingzhu He

Optical spectroscopy of Nd3+ in LiLuF4 single crystals

The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of Nd3+ : LiLuF4 crystals are measured at room temperature. The peak absorption cross-sections are 6.944×10−20 cm2 and 1.664 × 10−20 cm2 at around 795 nm with full-width at half-maximum of 3.4 nm and 3.2 nm for π-polarization and σ-polarization, respectively. Based on Judd–Ofelt theory, the spectral parameters of Nd3+ in LiLuF4 crystals are investigated. The emission probabilities, branching ratio and radiative lifetime for the transitions from 4F3/2 are calculated. The radiative lifetime, fluorescence lifetime and quantum efficiency are 536 µs, 489 µs and 91%, respectively. Its spectroscopic parameters are also compared with those of some other important Nd3+-doped laser crystals.

Optical properties of Dy3+ ion in PbF2 laser crystal

High-quality Dy:PbF2 crystal is grown by the Bridgman method in a nonvacuum atmosphere. By measuring the area under absorption bands, the experimental oscillator strengths are determined. The Judd–Ofelt (JO) intensity parameters Ωλ (λ = 2, 4, 6) are evaluated by the least-squares fit method. These phenomenological parameters are used to predict radiative transition probabilities, radiative lifetime and branching ratios for various excited levels of the Dy3+:PbF2 crystal. Photoluminescence spectra and lifetime of 6H13/2 levels of the Dy3+ ions have been measured. The laser transitions with most potential are identified and the utility of the PbF2 crystal as laser active material is discussed.

Optical characterization and evaluation of the laser properties of Yb3 + -doped (La, Sr)(Al, Ta)O3 single crystals

A Yb(3+)-doped mixed-perovskite single crystal (La, Sr)(Al, Ta)O(3) (LSAT) crystal is grown by the Czochralski method. The absorption spectrum, fluorescence spectrum and fluorescence lifetime of Yb(3+) ions have been investigated, and the spectroscopic parameters of Yb:LSAT have also been calculated. This crystal exhibits a remarkably large ground-state splitting (about 1100 cm(-1)), a relatively long fluorescence lifetime (0.85 ms) and broad absorption and emission bandwidths. The results indicate that the Yb(3+):LSAT crystal is a good candidate for diode-pumped ultrashort and tunable solid-state laser applications.

Spectroscopic characterization and diode-pumped 910 nm laser of Nd:LiLuF4 crystal

Polarized absorption and fluorescence spectra Nd3+-doped LiLuF4 single crystal were investigated. The peak emission cross section at 905 and 910 nm are 0.97 × 10−20 and 0.82 × 10−20 cm2, respectively. Two samples with different dimensions were tested in the laser experiments. With a laser-diode as the pump source, a maximum 1.17 W laser output at 910 nm has been obtained with a slope efficiency of 16.3% with respect to the pump power.