D. Z. Li

Ultrashort pulse temporal contrast enhancement based on noncollinear optical-parametric amplification

A pulse clean technique in time domain combining noncollinear optical-parametric amplification and second-harmonic generation is demonstrated. The measurement-limited >10(10) temporal contrast ratio of the 0.5 mJ/40 fs pulse near 800 nm is obtained over a large temporal range extending from <1 ps before the main pulse. The contrast ratio enhancement as fourth power of the initial contrast is demonstrated. The total efficiency is >6% for the 8.2 mJ/40 fs initial incident femtosecond pulse.

Diode-pumped continuous wave and Q-switched operation of Nd:LuAG crystal

The continuous wave (CW) and passively Q-switched performances of Nd:LuAG crystal were demonstrated. With a laser diode as pump source, the CW output power of 2.18 W was obtained under the pump power of 4.62 W, corresponding to the optical conversion efficiency of 47.2% and the slope efficiency of 52.2%. For Q-switching experiments, the shortest pulse width, largest pulse energy, and highest peak power were measured to be 12 ns, 50.6 μJ, and 4.21 kW, respectively.

Femtosecond and continuous-wave laser performance of a diode-pumped Yb3+:CaYAlO4 laser.

The cw and femtosecond laser operations of Yb(3+):CaYAlO(4) (Yb:CYA) are demonstrated. The laser emitted a maximum cw power of 1.94 W with a slope efficiency (η(slope)) of 71% and an optical-to-optical efficiency (η(opt)) of 51%. Under mode-locking operation, the laser emitted near transform-limited pulses with 156 fs pulse width, 8.1 nJ pulse energy and 0.74 W average power. The η(slope) and η(opt) of the mode-locked laser were 37% and 20%, respectively.

CW laser properties of Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG mixed crystals

Three mixed crystals, Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG, were grown by Czochralski method. We report the continuous-wave (CW) Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG laser operation under laser diode pumping. The maximum output powers are 4.11, 5.31, and 7.47 W, with slope efficiency of 73.0, 55.3, and 57.1%, respectively. With replacing Lu3+ or Y3+ ions with large Gd3+ ions, the pump efficiency increases.

Evidence of dissipative solitons in Yb 3+ :CaYAlO 4

Operation of an end-pumped Yb³⁺:CaYAlO₄ laser operating in the positive dispersion regime is experimentally investigated. The laser emitted strongly chirped pulses with extremely steep spectral edges, resembling the characteristics of dissipative solitons observed in fiber lasers. The results show that dissipative soliton emission constitutes another operating regime for mode locked Yb³⁺-doped solid state lasers, which can be explored for the generation of stable large energy femtosecond pulses.

Diode-pumped femtosecond Yb:CaNb2O6 laser

We report to our knowledge a diode-pumped passively mode-locked Yb:CaNb(2)O(6) (Yb:CN) laser for the first time. Both CW and passive mode-locking operation of the laser are experimentally investigated. A maximum CW output power of 1.4 W with a slope efficiency of 20% is obtained on a 7 mm long 1.5 at.% Yb:CN crystal, while stable passive mode-locking with a commercial semiconductor saturable absorption mirror (SESAM) was achieved on a 3 mm long 3 at.% Yb:CN crystal. The mode-locked pulses have pulse width of 251 fs and an average output power of 44 mW at 1038 nm.

Continuous-wave and passively Q-switched Nd:LYSO lasers

Continuous-wave (CW) and passively Q-switched performance of a Nd-doped oyorthosilicate mixing crystal, (Nd0.005Lu0.4975Y0.4975)2SiO5 (Nd:LYSO), were reported. As a result, new dual-wavelength all-solid-state lasers at 1075 and 1079 nm were achieved. When the absorbed pump power was 3.87 W, the CW laser produced 1.1 W output, corresponding to an optical conversion efficiency of 28.4% and a slope efficiency of 32.4%. By using a Cr4+:YAG wafer as the saturable absorber, we achieved Q-switching operation of Nd:LYSO crystal. The maximal average output power, shortest pulse width, largest pulse energy and highest peak power were measured to be 294 mW, 27.5 ns, 34.3 μJ and 1.18 kW, respectively. By difference frequency, these dual-wavelength lasers have potential applications for the generation of a broadband coherent radiation from 0.7–1.3 THz.

A highly efficient diode-pumped passively mode-locked Nd:Lu1.5Y1.5Al5O12 laser

In this letter, a diode-pumped passively mode-locked Nd:Lu1.5Y1.5Al5O12 (Nd:LuYAG) laser is demonstrated for the first time, to the best of our knowledge. With a semiconductor saturable-absorber mirror, a maximum output power of 0.85 W at 1064 nm was obtained under an absorbed power of 8.51 W, corresponding to a high slope efficiency of 44%. The mode-locked pulses were estimated to be 6.6 ps. The results of our experiment show that Nd:LuYAG crystal could be a promising material for diode-pumped ultra-short laser generation.

Crystal growth, spectroscopic and CW laser properties of Nd0.03Lu2.871Gd0.099Al5O12 crystal

Nd0.03Lu2.871Gd0.099Al5O12 (Nd:LuGdAG) crystal was grown by the Czochralski method. The absorption, fluorescence spectra and fluorescence lifetime of Nd:LuGdAG crystal at room temperature were investigated for the first time. We reported the continuous-wave (CW) Nd:LuGdAG laser operation under diode pumping. Output power of 1.43 W at 1064 nm was achieved with a slope efficiency of 34.1%. All the results show that Nd:LuGdAG crystal is a promising laser material.

Laser performance of holmium-doped Lu3Al5O12 and (Lu,Y)3Al5O12 crystals pumped by Tm:fiber laser

Optical properties of Ho3+-doped Lu3Al5O12 and (Lu,Y)3Al5O12 crystals were investigated and compared. Substitution of Y for Lu in the host garnet Lu3Al5O12 results in broad absorption and emission spectra, and improvements in the laser behavior of Ho3+. Pumped by Tm:fiber laser, a maximum output power of 5.02 and 5.73 W of Ho-doped Lu3Al5O12 and (Lu,Y)3Al5O12 have been obtained, respectively. The center lasing wavelength are 2124.5 and 2123.0 nm for Lu3Al5O12 and (Lu,Y)3Al5O12, respectively.