Chenlin Du

Efficient passive Q-switching operation of a diode-pumped Nd:GdVO 4 laser with a Cr 4+ :YAG saturable absorber

A diode-pumped highly efficient Cr4+:YAG passively Q-switched Nd:GdVO4 laser formed by a plano–concave resonator has been demonstrated. At the highest attainable absorbed pump power of 11.4 W, 4.05 W of average output power, which was two thirds of the maximum corresponding cw output, was achieved with an optical conversion efficiency of 35.5%, and the slope efficiency was determined to be 46.8%, reaching 85% of the magnitude of its cw counterpart. The resulting shortest pulse duration, single-pulse energy, and peak power were found to be 13 ns, 90 μJ, and 7 kW, respectively, with a pulse repetition frequency (PRF) of 45 kHz. Two particularly modified resonator configurations were employed; the largest pulse energy and the highest peak power reached were, respectively, 154 μJ and 11.2 kW at 8.5 W of absorbed pump power. An analytical relation between the PRF and the absorbed pump power is given for a passively Q-switched laser, showing good consistency with experiment with a Nd:GdVO4 laser. The dependence of the operational parameters on the pump power and on the output coupling was also investigated experimentally. Issues involving the criterion for passive Q switching are discussed in some detail for Cr4+:YAG passively Q-switched neodymium-doped vanadate lasers.

Pulsed laser output of LD-end-pumped 1.34µm Nd: GdVO 4 laser with Co: LaMgAl 11 O 19 crystal as saturable absorber

The absorption spectra of the 0.5at.% and 1at.% Co: LaMgAl11O19 (LaMg1-xCoxAl11O19, x=0.005 and 0.01, abbreviated as Co:LMA) crystals were measured at room temperature, and the results show that the Co: LMA crystals have two absorption bands, and the absorption band located at 1030-1660 nm can be used for a passive saturable absorber Q switch of 1.3-1.6mum laser. The passive pulsed laser output of LD-end-pumped Nd:GdVO4 1.34mum laser was demonstrated for the first time by using the 0.5 at.% Co:LMA crystal as a saturable absorber Q switch. The maximum average output power of 500 mW was obtained under the pumping power of 25 W. The shortest pulse width, the largest pulse energy and the highest peak power were obtained to be 160 ns, 25.5muJ and 150 W, respectively.

High-power actively Q-switched Nd:GdVO4 laser end-pumped by a fiber-coupled diode-laser array

Abstract An end-pumped acousto-optically Q-switched Nd:GdVO 4 laser has been demonstrated, from which 7.25 W average output power at 1.06 μm at pulse repetition frequency (PRF) of 60 kHz was obtained with an optical conversion efficiency of 38.1% and an averaged slope efficiency of 43.5%. At incident pump power of 17 W, the highest single pulse energy and peak power were achieved when the laser was operated at a PRF of 10 kHz, and were determined to be 340 μJ and 26.2 kW, respectively. The shortest laser pulse with FWHM width of 11 ns was observed at PRF of 20 kHz. Through intracavity frequency doubling, we obtained 2.18 W average green output power with pulse width of 45 ns at a PRF of 25 kHz, the corresponding optical conversion efficiency was 21.8%, and the resulting single pulse energy and peak power were determined to be 87.2 μJ and 1.94 kW, respectively. The results of theoretical calculations on the basis of rate equations are also presented, showing close consistency with the experimental data.

Growth of new laser crystal Nd:LuVO4 by the Czochralski method

Abstract In this paper, the polycrystalline materials of LuVO 4 and NdVO 4 have been synthesized by liquid-phase method, and the new laser crystal Nd:LuVO 4 has been successfully grown by the Czochralski method. The X-ray experimental results show that the polycrystalline materials of LuVO 4 and NdVO 4 , and the as-grown Nd:LuVO 4 crystal all possess the structure of ZrSiO 4 . The laser output of Nd:LuVO 4 crystal is performed when it is pumped by a laser diode.

High-power Nd:GdVO4 laser at 1.34 μm end-pumped by laser-diode-array

Abstract A diode-end-pumped high-power Nd:GdVO 4 laser operating at 1.34 μm has been demonstrated. The maximum continuous-wave output power of 4.62 W was obtained at the incident pump power of 14.75 W, with the corresponding optical conversion efficiency of 31.3% and the average slope efficiency of 33.1%. By using the experimentally measured threshold pump power and slope efficiency, the stimulated emission cross-section of Nd:GdVO 4 crystal at 1.34 μm was determined to be 1.78×10 −19 cm 2 .

Actively Q-switched intracavity second-harmonic generation of 1.06 μm in BiB3O6 crystal

Abstract We have investigated the acousto-optically Q-switched intracavity second-harmonic generation of 1.06 μm in a 1.9-mm-long BiB3O6 crystal, cut for type-I phase-matching direction of (θ,ϕ)=(168.9°,90°), performed in a diode-end-pumped Nd:YVO4 laser. When the incident pump power was 4.3 W at 30 kHz of pulse repetition frequency, a maximum average green output power of 480 mW , the shortest pulse with FWHM width of 72 ns , the highest single pulse energy of 16 μJ and the maximum peak power of 222 W were obtained, giving the corresponding optical conversion efficiency of 11.2%. The effect of varying temperature in BIBO crystal on the average green output power was also investigated.

Growth and properties of mixed crystal Nd:YGdVO4

Abstract Different Gd/Y polycrystalline materials were synthesized by a liquid-phase reaction method and several Nd:YGdVO 4 crystals with low Nd ion concentrations were successfully grown by the Czochralski method. A component analysis was made and the absorption, emission spectra had been measured. The influence of different Gd/Y ratios on the laser properties was also investigated for the first time. The laser experiments have proved that Nd:YGdVO 4 crystals are good laser materials.

Diode-pumped Q-switched Nd:GdVO4/KTP green laser formed with a flat–flat resonator

Abstract A diode-pumped acousto-optically Q-switched intracavity frequency-doubled Nd : GdVO 4 / KTP green laser formed with a flat–flat resonator was demonstrated. 3.05 W of average green output power at pulse repetition frequency (PRF) of 40 kHz was obtained with an optical conversion efficiency of 18.4%, the effective intracavity frequency-doubling efficiency was 57%. At the incident pump power of 15 W , the shortest laser pulse occurred at PRF of 25 kHz with FWHM width of 14 ns , yielding the highest peak power of 7.44 kW ; while the largest pulse energy of 0.14 mJ was achieved at PRF of 15 kHz .

LD-pumped actively Q-switched Nd:GdVO4/KTP red laser

Abstract LD-pumped actively Q-switched intracavity frequency-doubled Nd:GdVO4/KTP red laser has been introduced. A maximum red average output power of 0.78 W at 671 nm was obtained at pulse-repetition frequency (PRF) of 15 kHz and the optical conversion efficiency was 6.5%. At the incident pump power of 12 W , the shortest laser pulse occurred at PRF of 15 kHz . Its full-width at half-maximum and the highest peak power were measured to be 35.8 ns and 3.38 kW . The largest single pulse energy of 56.3 μJ was achieved at PRF of 10 kHz . The influence factors on the Q-switched Nd:GdVO4/KTP red laser have been discussed.

Growth, Luminescence Properties and Laser Characterization of Nd:GdVO4 Crystal at 1.34 µm

Using the Czochralski method, Nd:GdVO4 single crystals have been successfully grown with polycrystalline materials synthesized by a liquid-phase method. Luminescence properties of these crystals are determined. The fluorescence lifetime of 0.52 at% Nd-doped GdVO4 crystal is 150 µs. Nd:GdVO4 crystal exhibits a concentration quenching effect. The Nd:GdVO4 crystal samples with different Nd concentrations were used in laser experiments at 1.34 µm pumped by a high-power laser diode (LD). This is the first time report that a laser with a power of up to 4.64 W at 1.34 µm has been achieved with a slope efficiency of 32.9%.