Peizhen Deng

Dependence of the Yb3+ emission cross section and lifetime on temperature and concentration in yttrium aluminum garnet

Measurements are reported of the spectroscopic properties (absorption and emission spectra, stimulated-emission cross section, and radiative lifetime) of (YbxY1-x)3Al5O12 for nominal x values of 0.025, 0.05, 0.1, 0.2 and 0.3 at temperatures of 15–300 K. The emission cross sections of Yb:YAG with different Yb3+ concentrations were determined by use of the Fuchtbauer–Ladenburg formula and the reciprocity method. At low temperatures, the product (στ) of the effective stimulated-emission cross section and the radiative lifetime is greater than at room temperature for all concentrations. Product στ is nearly independent of Yb3+ concentration at a given temperature. These results will aid in the design of high-power thin disk lasers by use of highly doped Yb:YAG.

Passively Q-switched Yb : YAG laser with Cr4+: YAG as the saturable absorber

By using a continuous-wave Ti:sapphire laser as a pumping source, we demonstrated a passively Q-switched Yb:YAG laser at room temperature with Cr(4+):YAG as the saturable absorber. We achieved an average output power of as much as 55 mW at 1.03 mum with a pulse width (FWHM) as short as 350 ns. The initial transmission of the Cr(4+):YAG has an effect on the pulse duration (FWHM) and the repetition rate of the Yb:YAG passively Q-switched laser. The Yb:YAG crystal can be a most promising passively Q-switched laser crystal for compact, efficient, solid-state lasers.

Laser-diode-pumped Cr 4+ ,Nd 3+ :YAG with self-Q-switched laser output of 1.4 W

By use of a laser diode as a pump source, a self-Q-switched laser from a Cr, Nd:YAG crystal is demonstrated. The output Q-switched traces are very stable, the threshold pump power is 3.5 W, the pulse duration is 50 ns, and the slope efficiency is as high as 20%. In addition, the pulse width remains constant while the pulse repetition rate varies with pump power.

Passively Q-switched diode-pumped Yb:YAG laser using Cr4+-doped garnets

Abstract We investigate the repetitive modulation in the kHz frequency domain of a passively Q-switched, diode-pumped Yb:YAG laser, by Cr 4+ :YAG, Cr 4+ :LuAG, and Cr 4+ :GSGG saturable absorbers. The results presented here are focused towards the design of a passively Q-switched Yb:YAG microlaser. The free-running performance of both rod and a disk Yb:YAG is characterized and experimental parameters such as gain and loss are evaluated. These values, together with the value of the stimulated emission cross-section, e.g. σ em =3.3×10 −20 cm 2 were found to fit between our experimental results and an existing numerical model which relates the experimental and physical parameters to the minimal threshold pumping power. Q-switched pulses with maximum peak power of ≈10.4 kW, with energy of ≈0.5 mJ/pulse, were extracted with 30% extraction efficiency.

The influence of Yb concentration on laser crystal Yb:YAG

Abstract The thermal properties, absorption spectra and Raman spectra of Yb:YAG crystal with different Yb 3+ ion concentrations are reported. The results show that the ytterbium concentration influences the properties of Yb:YAG. At high doping level, the thermal conductivity decreases and the absorption peak centered at about 940 nm shifts to shorter wavelength. The Raman spectra reveal that the lattice vibrational modes of highly doped Yb:YAG is different from that of low-doped Yb:YAG crystal. The effect of Yb 3+ concentration on the properties is regarded as the result of lattice deformation. The influence of Yb concentration on laser is also analyzed.

Yb:tellurite laser glass with high emission cross-section

The emission cross-section for the 2F5/2–2F7/2 transition of Yb3+ has been determined from absorption and emission measurements of tellurite glasses at room temperature. By systematic variations in the spectroscopic properties with composition, glass composition with emission cross-sections more than 2.30 pm2 and fluorescence lifetimes longer than 0.90 ms were obtained and have the advantage over some excellent laser glasses reported in published papers.

Structural, thermal, and luminescent properties of Yb-doped Y 3 Al 5 O 12 crystals

Yb-doped Y3Al5O12 (Yb:YAG) single crystals were grown by the Czochralski method. The effects of various Yb3+ concentrations on structural distortion, density, and thermal expansion of Yb:YAG laser crystals are discussed. The fluorescence spectra, fluorescence lifetimes, and color-center absorption spectra of as-grown and annealed Yb:YAG with various doping levels were measured at room temperature. The effects of color centers on the fluorescence intensity and lifetime of Yb:YAG were also investigated.

Highly doped Nd : YAG crystal used for microchip lasers

The highly doped Nd:YAG (Nd concentration as high as 3 at.%) crystals were grown by the temperature gradient technology. The spectral properties of these highly doped Nd:YAG crystals were reported and compared with that of the traditional Nd:YAG (1.1 at.% Nd) grown by the Czochralski method. Although concentration quenching exists in highly doped Nd:YAG crystals, the laser performances have demonstrated that highly doped Nd:YAG crystals have the advantages over that of the traditional grown Nd:YAG such as efficiencies, especially used in microchip lasers.

Growth of high-quality single crystal of 50 at.% Yb:YAG and its spectral properties

The Czochralski crystal growth of 50 at.% Yb:YAG single crystal was reported. The absorption spectrum, emission spectrum and fluorescence lifetime of Yb:YAG crystal were measured at room temperature. The spectroscopic parameters of nominal 50 at.% Yb:YAG crystal were compared with that of Yb:YAG crystal with low doping level. The results indicate that Yb:YAG crystals with high doping level are potential candidates used for compact, efficient thin chip lasers.

The effect of Cr concentration on emission cross-section and fluorescence lifetime in Cr,Yb:YAG crystal

Abstract The emission cross-section, and fluorescence lifetime of Cr,Yb:YAG with different concentration of Cr4+ and Yb:YAG were measured. With the increase of Cr concentration in Cr,Yb:YAG, the emission cross-section keeps constant and fluorescence lifetime decreases. The quantum efficiency decreases and the energy transfer efficiency from Yb3+ to Cr4+ increase as the Cr concentration increases in Cr–Yb-co-doped Cr,Yb:YAG system. The nonradiative Yb3+→Cr4+ energy transfer is consistent with an electric dipole–dipole interaction mechanism. The optimum Cr concentration for Cr,Yb:YAG was estimated. Also the potential of Cr,Yb:YAG as a self-Q-switched laser crystal was discussed.