Qibiao Dai

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.

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.

Generation of 2.6-mJ 400-kW pulses from a compact Yb:Gd 3 Ga 5 O 12 laser repetitively Q-switched by an acousto-optic modulator

An efficient, acousto-optically Q-switched, and compact Yb:Gd(3)Ga(5)O(12) laser oscillating around 1026 nm is demonstrated, producing an output power of 5.15 W at a pulse repetition rate of 2 kHz, with optical-to-optical and slope efficiencies being 35.8% and 52%, respectively. The generated laser pulses are 6.4 ns in duration (FWHM), with pulse energy and peak power amounting, respectively, to 2.58 mJ and 403 kW.

Passive Q-switching laser performance of Yb:Gd3Ga5O12 garnet crystal.

We report on the passive Q-switching laser performance of the Yb:Gd3Ga5O12 garnet crystal. With a Cr4+:YAG crystal used as saturable absorber for passive Q-switching, an average output power of 5.31 W was produced at a pulse repetition rate of 62.5 kHz, the optical-to-optical and slope efficiencies being, respectively, 45% and 61%. Laser pulses of 140 μJ in energy and 5.8 ns in duration were also obtained at 22.2 kHz, with a corresponding peak power amounting to 24.1 kW.

Actively Q-switched compact Yb:YSGG laser generating 3.1 mJ of pulse energy.

An efficient compact Yb:Y(3)Sc(1.5)Ga(3.5)O(12) garnet crystal laser actively Q-switched with an acousto-optic modulator is demonstrated, producing stable pulses at repetition rates ranging from 1 to 30 kHz. With 10.8 W of pump power absorbed, an average output power of 3.1 W at 1025.7 nm is generated at pulse repetition rate of 1 kHz, with a slope efficiency of 46%. The resulting pulse energy, duration, and peak power are 3.1 mJ, 23.9 ns, and 130 kW, respectively.

Efficient Q-Switched Miniature

We report on a very compact, highly efficient, passively Q-switched Yb:Gd3Ga5O12 crystal laser pumped at 935 nm by a diode, from which an average output power of 2.36 W at 1025 nm was produced at a pulse repetition rate of 7.7 kHz with a slope efficiency of 60%; the resulting pulse energy and duration were, respectively, 306 μJ and 1.7 ns, leading to a peak power amounting to 180 kW.

{\rm Yb{:}Gd}_{3}{\rm Ga}_{5}{\rm O}_{12}

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.

Laser Generating 180 kW of Peak Power

We have conducted an investigation into the continuous-wave (CW) and passive Q-switching laser performance of the Yb:YCa4O(BO3)3 (Yb:YCOB) crystal, aiming to evaluate its capability of power or energy scaling in compact end-pumped lasers. Efficient CW laser operation was realized with output coupling changed over a wide range from 0.4% to 60%. Operating in CW mode in the long-wavelength sideband around 1085 nm, the Z-cut Yb:YCOB laser produced an output power of 10.7 W with an optical-to-optical efficiency of 56%; in CW operation of the Y-cut Yb:YCOB laser oscillating in the main emission band, an output power of 17.0 W was reached, with optical-to-optical and slope efficiencies being respectively 62% and 78% (with respect to incident pump power). In passive Q-switching regime, the X-cut crystal proved to be the most advantageous in generating high average power and high pulse energy. With a Cr4+:YAG crystal plate serving as saturable absorber whose initial transmission was T0 = 97.5%, and with an output coupling of T = 20%, an average output of 10.72 W was generated at a pulse repetition rate of 26.3 kHz, the resulting pulse duration was 22.3 ns. While under Q-switching operational conditions of T0 = 90.0% and T = 40%, a maximum average output power of 4.13 W could be reached at a rather low repetition rate of 3.23 kHz, yielding a pulse energy that was as high as 1.28 mJ, the resulting pulse duration and peak power being 5.0 ns and 256 kW, respectively.

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