Diode-pumped passively Q-switched mode-locked Nd:YLF laser with uncoated GaAs saturable absorber

We have demonstrated passively Q-switched mode-locked all-solid-state Nd:YLF laser with an uncoated GaAs wafer as saturable absorber and output mirror simultaneously. Q-switched mode-locking pulses laser with about 100% modulation depth were obtained. The average output power is 890 mW at the incident pump power of 5.76 W, corresponding to an optical slop efficiency of 20%. The temporal duration of mode-locked pulses was about 21 ps. At the Q-switched repetition rate of 30 kHz, the energy and peak power of a single pulse near the maximum of the Q-switched envelope was estimated to be about 1.6 μJ and 76 kW.     

Diode-pumped passively Q-switched mode-locked Nd:LuVO4 laser with a semiconductor saturable absorber mirror

We present a compact passively Q-switched mode-locked Nd:LuVO₄ laser run in a Z-type folded cavity with semiconductor saturable absorber mirror (SESAM). The repetition rates of the passively Q-switched pulse envelope ranges from 22.99 to 141.18 kHz as the pump power increased from 2.372 to 8.960 W. The repetition rates of mode-locked laser pulses in the Q-switched pulse envelope has 111 MHz determined by the cavity length and the mode-locked pulse duration is evaluated to be 257 ps. An average output power of 823.5 mW is achieved at the pump power of 8.96 W, corresponding to an optical conversion efficiency of 9.2%.     

Diode-pumped passively Q-switched YAG/Yb:YAG laser with Cr4+:YAG as a saturable absorber

We design an efficient passively Q-switched laser using a composite YAG/Yb:YAG crystal as the laser gain medium and a Cr⁴⁺:YAG crystal as a saturable absorber. We obtain an average output power of 1.81 W in 1030 nm laser at an absorbed pump power of 4.8 W, corresponding to an optical-to-optical efficiency of 37.7% and a slope efficiency of 47.3%. The pulsed laser has a repetition rate of about 28.6 kHz and a pulse width of 15.8 ns, with the highest peak power of 4 kW. In addition, using a LBO as the intracavity frequency doubler, we obtain a maximum power of 246 mW in 515 nm pulsed laser at an absorbed pump power of 3.8 W.     

Diode end-pumped passively Q-switched Nd:YAG ceramic laser with Cr4+:YAG saturable absorber

We report on a diode end-pumped passively Q-switched Nd:YAG ceramic laser. By using a Cr⁴⁺:YAG single crystal with an 80% initial transmission as the saturable absorber, stable Q-switched pulses with a 126-μJ pulse energy, a 12-ns pulse width, and an 8.4-kHz pulse repetition rate have been obtained. The Q-switching performance of the laser under different saturable absorption strengths and output couplings was experimentally investigated.     

Diode-pumped Nd:YAG ceramic laser at 946 nm passively Q-switched with a Cr4+:YAG saturable absorber

We demonstrate a diode-pumped Nd:YAG ceramic laser with emission at 946 nm that is passively Q-switched by single-crystal Cr⁴⁺:YAG saturable absorber. An average output power of 1.7 W is measured under 18.4 W of incident power using an output mirror with transmission T=4%. The corresponding optical-to-optical efficiency is 9.2%. The laser runs at a pulse repetition rate of 120 kHz and delivers pulses with energy of 14 μJ and duration of 80 ns, which corresponds to a peak power of 175 W.     

Optimization of passively Q-switched and mode-locked laser with Cr:YAG saturable absorber

By considering the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density, the coupled rate equations for a diode-pumped passively Q-switched and mode-locked (QML) laser with Cr⁴⁺:YAG saturable absorber are given. These coupled rate equations are solved numerically and the key parameters of an optimally coupled passively QML laser are determined for the first time. These key parameters include the parameters of the gain medium, the saturable absorber and the resonator, which can maximize the pulse energy of singly Q-switched envelope. The optimal calculations for a diode-pumped passively QML Nd:GdVO₄ laser with Cr⁴⁺:YAG saturable absorber are presented to demonstrate the numerical simulation applicable.     

Diode-pumped Q-switched and mode-locked Nd:LuVO4/KTP green laser with AO and Cr4+:YAG saturable absorber

A diode-pumped Q-switched and mode-locked (QML) Nd:LuVO₄/KTP green laser with acousto-optic modulator (AOM) and Cr⁴⁺:YAG saturable absorber is presented. By inserting an AOM into the laser cavity, the stability of the QML green laser pulse with AO and Cr⁴⁺:YAG is improved, the modulation depth is increased and the pulse width of Q-switched pulse envelope is significantly compressed in comparison with that of the singly passively QML green laser with Cr⁴⁺:YAG. The experimental results show that the peak power of the doubly QML green laser pulse is much higher than that of the singly passively QML green laser pulse.     

Diode-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber

The intracavity photon density is assumed to be of Gaussian spatial distributions and its longitudinal variation is also considered in the rate equations for a laser diode(LD)end-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber.These space-dependent rate equations are solved numerically.The dependences of pulse width,pulse repetition rate,single-pulse energy,and peak power on incident pump power are obtained.In the experiment,the LD end-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber is realized and the experimental results are consistent with the numerical solutions.     

Diode-pumped, Cr:YAG passively Q-switched and mode-locked Nd:YVO_4/KTP green laser

The phenomena of simultaneous Q-switching and mode-locking in a diode-pumped Nd:YVO4/Cr:YAG/ KTP green laser are reported and discussed in this paper. With 5.3-W pump power, by using a nearly hemispherical cavity (the cavity length is only 97 mm), the results of modulation depth of 70% and the period of 0.6 ns are obtained, the output power and the repetitive frequency of Q-switched pulse are 90 mW and 12 kHz, respectively.     

LD-pumped passively Q-switched Nd:YVO4/YVO4 laser with an Nd3+:Cr4+:YAG saturable absorber

By using a piece of codoped Nd³⁺:Cr⁴⁺:YAG crystal as a saturable absorber, a laser-diode pumped passively Q-switched Nd:YVO₄/YVO₄ laser has been realized. The maximum laser output power of 2.452 W has been obtained at the incident pump power of 8.9 W for an 8.8% transmission of the output coupler at 1064 nm, corresponding to a slope efficiency of 30%. The other output laser characteristics of the laser have also been investigated. The laser with a Nd³⁺:Cr⁴⁺:YAG saturable absorber has a lower threshold pump power and a higher slope efficiency compared to that with a similar small-signal transmission of a Cr⁴⁺:YAG saturable absorber.     

Diode-pumped doubly Q-switched YVO4/Nd:YVO4 laser with BBO electric-optic Q-switch and Cr4+:YAG saturable absorber

In the experiment, we have demonstrated the performance of a laser-diode, end-pumped, doubly Q-switched YVO₄/Nd:YVO₄ laser with both a BBO electric-optic (EO) Q-switch and Cr⁴⁺:YAG saturable absorber. At a maximum incident pump power of 15 W and an EO Q-switch repetition rate of 8 kHz, the stable laser pulses with the pulse duration 5.28 ns, the single pulse energy 0.14 mJ, and the pulse peak power 26 kW are obtained. The experimental results show that the double Q-switched laser with EO and Cr⁴⁺:YAG can generate the shorter pulse and the higher peak power in comparison to singly Q-switched laser with EO.     

Diode-pumped passively Q-switched Nd:GGG crystal with GaAs saturable absorber

We have experimentally studied the passive Q-switching performance of a diode-pumped Nd-doped gadolinium gallium garnet (Nd:GGG) laser with a GaAs saturable absorber. Stable Q-switched pulses as short as 9 ns with a repetition rate of 196.1 kHz have been obtained with an appropriately coated GaAs wafer used as the output coupler. At 12.44 W of the absorbed pump power, an average output power of 1.03 W has been obtained and the corresponding pulse energy and peak power are 5.25 μJ and 0.58 kW, respectively.     

Comparison between c-cut and a-cut Nd:YVO4 lasers passively Q-switched with a Cr4+:YAG saturable absorber

Comparison between c-cut and a-cut Nd:YVO₄ microchip lasers passively Q-switched with a Cr⁴⁺:YAG saturable absorber is experimentally made. The lower emission cross section of the c-cut Nd:YVO₄ crystal can enhance the passive Q-switching effect to produce a peak power 10 times higher than that obtained with the a-cut crystal. The experimental result further reveals that a c-cut Nd:YVO₄ crystal is a very convenient material for short-pulse (sub-nanosecond) and high-peak-power (>10 kW) lasers. Received:10December2001/Revisedversion:22January2002 / Published online: 14 March 2002     

Optimization of diode-pumped passively Q-switched mode-locked c-cut Nd:GdVO4 laser with a GaAs saturable absorber

By considering the single-photon absorption (SPA) and two-photon absorption (TPA) processes in the GaAs saturable absorber, the coupled rate equations for a diode-pumped passively Q-switched and mode-locked (QML) laser with GaAs coupler under Gaussian approximation are given. The key parameters of an optimally coupled passively QML laser can be obtained by numerically solving these equations. These key parameters include the parameters of the gain medium, the saturable absorber and the resonator, which can maximize the pulse energy of singly Q-switched envelope. Sample calculations for a diode-pumped passively Q-switched mode-locked c-cut Nd:GdVO₄ laser with a GaAs saturable absorber are presented to demonstrate the optimal method applicable.     

Efficient passively Q-switched operation of a diode-pumped Nd:GGG laser with a Cr:YAG saturable absorber

The continuous-wave (cw) and passive Q-switching operation of a diode-end-pumped gadolinium gallium garnet doped with neodymium (Nd:GGG) laser at 1062 nm was realized. A maximum cw output power of 6.9 W was obtained. The corresponding optical conversion efficiency was 50.9%, and the slope efficiency was determined to be 51.4%. By using Cr⁴⁺:YAG crystals as saturable absorbers, Q-switching pulse with average output power of 1.28 W, pulse width of 4 ns and repetition rate of 6.2 kHz were obtained. The single-pulse energy and peak power were estimated to be 206 μJ and 51.6 kW, respectively. The conversion efficiency of the output power from cw to Q-switching operation was as high as 84.7%.     

High-power diode-pumped Q-switched and mode-locked Nd:YVO(4) laser with a Cr(4+):YAG saturable absorber

We demonstrate a high-power passively Q -switched and mode-locked Nd:YVO(4) laser with a Cr(4+):YAG saturable absorber. 2.7 W of average power with an 18-kHz Q -switched repetition rate was generated at a 12.5-W pump power. The peak power of a single pulse near the maximum of the Q -switched envelope was greater than 100 kW.     

Pulse compression in AO Q-switched diode-pumped Nd:GdVO4 laser with Cr4+:YAG saturable absorber

By simultaneously using both an acoustic-optic (AO) modulator and a Cr⁴⁺:YAG saturable absorber in the cavity, for the first time, a diode-pumped doubly Q-switched Nd:GdVO₄ laser has been realized. The pulse duration is obviously compressed in contrast to the actively acoustic-optic Q-switched laser. By considering the Gaussian transversal distribution of the intracavity photon density and the longitudinal distribution of the photon density along the cavity axis as well as the influence of turnoff time of the acoustic-optic (AO) Q-switch, we provide the coupled rate equations for a diode-pumped doubly Q-switched Nd:GdVO₄ laser with both an acoustic-optic (AO) modulator and a Cr⁴⁺:YAG saturable absorber. These coupled rate equations are solved numerically, and the dependence of pulse width, pulse energy and peak power on the incident pump power at different pulse repetition rates is obtained. The numerical solutions of equations agree well with the experimental results.This revised version was published online in August 2005 with a corrected cover date.     

Optimization of passively Q-switched laser with V:YAG saturable absorber

By considering the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density, the coupled rate equations for a diode-pumped passively Q-switched laser with V³⁺:YAG saturable absorber are given. These coupled rate equations are solved numerically and the key parameters of an optimally coupled passively Q-switched laser with V³⁺:YAG at 1342 nm are determined. These key parameters include the parameters of the gain medium, the saturable absorber and the resonator, which can maximize the pulse energy of singly Q-switched pulse. The optimal calculations for a diode-pumped passively Q-switched a-Nd:GdVO₄ laser with V³⁺:YAG saturable absorber are presented to demonstrate the numerical simulation applicable.     

Diode-pumped passively Q-switched Nd:GdVO4 laser at 1342 nm with V:YAG saturable absorber

We have demonstrated an efficient diode-pumped passively Q-switched Nd:GdVO₄ laser working at 1342 nm by using an uncoated V³⁺:YAG crystal as the saturable absorber, in which both a-cut and c-cut Nd:GdVO₄ crystals are employed. At the maximum absorbed pump power of 9.45 W, the maximum average output power can reach 519 mW and 441 mW corresponding to the output coupler with different transmission of 3% and 10% by using an a-cut Nd:GdVO₄ crystal at 1342 nm, while the shortest pulse duration could be as low as 21.7 ns and 22.3 ns with the repetition rate of 48.41 kHz and 53.25 kHz by using a c-cut Nd:GdVO₄ crystal, corresponding to the output coupler with different transmission of 3% and 10% at 1342 nm, and the single Q-switched pulse energy are 6.67 uJ and 7.06 uJ, the pulse peak power are 307 W and 316 W, respectively. The experimental results show that c-cut Nd:GdVO₄ laser can generate shorter pulse with higher peak power in comparison with a-cut one.     

Analysis of a laser-diode end-pumped passively Q-switched Nd:GdVO4 laser with V3+:YAG saturable absorber

By considering both the transversal and longitudinal Gaussian spatial distribution of the intracavity photon density, a couple of rate equations describing a laser-diode end-pumped passively Q-switched Nd:GdVO₄ laser with V³⁺:YAG saturable absorber have been proposed. Solving these space-dependent rate equations numerically, we obtain the dependences of pulse width, pulse repetition rate, single-pulse energy and peak power on pump power. In the experiment, a laser-diode end-pumped Nd:GdVO₄ laser passively Q-switched by a V³⁺:YAG saturable absorber has been realized, and the experimental results are consistent with the theoretical calculations.