Xueping Tian

Spectral and lasing investigations of Yb:YSGG crystal.

We report on a systematic study of the absorption and emission spectral properties of (Yb(0.1)Y(0.9))(3)(Sc(1.5)Ga(0.5))Ga(3)O(12) (Yb:YSGG) crystals. The broad fluorescence spectral lines indicate great potential of Yb:YSGG for tunable and ultrafast laser applications. Efficient continuous-wave (cw) laser oscillation was also demonstrated at room temperature (RT), generating an output power of 6.11 W with an optical-to-optical efficiency of 64.2%, and a slope efficiency of 80.1% with respect to absorbed pump power. The laser emission spectrum shifts to shorter wavelengths as the transmission of the output coupler varies from 3% to 20%, a result that can be explained based on the effective gain cross-sections of Yb:YSGG.

The potential of Yb:YCa 4 O(BO 3 ) 3 crystal in generating high-energy laser pulses

The passive Q-switching laser performance of Yb:YCa(4)O(BO(3))(3) is studied with crystals cut along the principal optical axes. Using a Cr(4+):YAG saturable absorber with initial transmission of 93.7% and an output coupler of transmission of 40%, efficient Q-switched laser operation is achieved with a X-cut crystal, generating an output power of 2.14 W at a pulse repetition rate of 4.5 kHz. The resulting laser pulse is 9.3 ns in duration, with the energy being as high as 476 μJ and the peak power amounting to 51.2 kW. The results demonstrated in this work reveal the great potential of this crystal in developing high-energy compact pulsed lasers.

Laser performance of ytterbium-doped gallium garnets: Yb:Re 3 Ga 5 O 12 (Re = Y, Gd, Lu)

We report on the results from a comparative study on the continuous-wave laser performance of Yb:YGG, Yb:LuGG, and Yb:GGG gallium garnets grown by the optical floating zone technique, conducted under identical experimental conditions. 5−7 W of output powers were generated with the three garnet crystals in a compact linear resonator longitudinally pumped by a diode laser emitting at 970−974 nm. The optical-to-optical and slope efficiencies measured for Yb:YGG amounted to 68% and 80%, respectively, which proved to be much higher than the corresponding efficiencies for Yb:LuGG (49% and 60%) or Yb:GGG (52% and 64%).

Highly efficient Q-switched laser operation of Yb:Y 3 Ga 5 O 12 garnet crystal

We demonstrate, for the first time, passively Q-switched laser operation of Yb:Y(3)Ga(5)O(12) garnet crystal. An output power of 4.53 W at 1031 nm was generated at a pulse repetition rate of 55.6 kHz, with a Cr(4+):YAG crystal acting as saturable absorber whose initial transmission was 97.5%, the corresponding pulse energy, duration and peak power were respectively 81.5 μJ, 28.5 ns and 2.86 kW. Laser pulses at a lower repetition rate of 18.2 kHz were also achieved at 1025 nm while the initial transmission of the Cr(4+):YAG crystal was 85.0%, with an output power measured to be 2.56 W, the resulting pulse energy, duration, and peak power being 140.8 μJ, 5.9 ns, and 23.9 kW, respectively.

Efficient laser operation of Yb:Lu 3 Ga 5 O 12 garnet crystal

Efficient laser operation is demonstrated at room temperature with a new Yb:Lu3Ga5O12 garnet crystal. A continuous-wave output power of 5.36 W is generated at a center oscillation wavelength of 1041 nm, with an optical-to-optical efficiency of 51% and the slope efficiency of 63%. In passively Q-switched operation, the maximum average output power reaches 4.0 W (center wavelength of 1034 nm) at a repetition rate of 71 kHz, with optical-to-optical and slope efficiencies measured to be 40% and 50%, respectively. Laser pulses of 26 ns duration are generated with a pulse energy of 91 μJ and peak power of 3.5 kW.

Efficient high-energy passively Q-switched Yb:GdCa4O(BO3)3 laser.

A compact diode-pumped high-pulse-energy Yb:GdCa(4)O(BO(3))(3) laser passively Q-switched with a Cr(4+):YAG saturable absorber is demonstrated at room temperature. An output power of 1.05 W is generated at a pulse repetition rate of 2.5 kHz when the pump power absorbed is 7.7 W, with a slope efficiency determined to be 40%. The laser pulse generated is 10.0 ns in duration, with pulse energy as high as 420 μJ and peak power amounting to 42 kW.

Polarization state of a continuous-wave Yb:NaY(WO4)2 disordered crystal laser

Output-coupling-dependent complex polarization state varying behavior is demonstrated for a continuous-wave Yb:NaY(WO4)2 disordered crystal laser. The laser oscillation can be purely ?-polarized if the output coupling used is kept lower than 5%; for output couplings that are higher than this level, however, the laser will undergo three successive operational regions with increasing pump power, in which ?-polarized, ?- and ?-polarized, and ?-polarized oscillations will be generated, respectively.

Improvement in continuous-wave laser performance of disordered Yb:CNGG crystal

We report on a significant improvement in cw laser performance of the disordered Yb:CNGG crystal. Very efficient cw laser operation is demonstrated at room temperature with a 3.5 mm thick crystal end pumped by a diode laser, generating an output power of 5.15 W with an optical-to-optical efficiency of 46%, whereas the slope efficiency amounts to 80%.