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.     

Optimization of Yb:YAG/Cr<Superscript>4+</Superscript>:YAG composite ceramics passively Q-switched microchip lasers

The laser characteristics of laser-diode end-pumped Yb:YAG/Cr⁴⁺:YAG composite ceramics microchip passively Q-switched lasers were studied by solving the coupled rate equations numerically taking into account the reabsorption of Yb:YAG ceramics at laser wavelength. Effects of the reflectivity of the output coupler, the concentrations and thickness of the saturable absorbers, and pump beam area on the laser performance were investigated analytically. The simulation results of the Yb:YAG/Cr⁴⁺:YAG composite ceramics passively Q-switched microchip lasers were in good agreement with the experimental data. Better laser performance (high peak power, short pulse width and good optical-to-optical efficiency) of the composite Yb:YAG/Cr⁴⁺:YAG ceramics passively Q-switched laser can be obtained by using a thin Cr⁴⁺:YAG ceramic with high concentration, suitable reflectivity of the output coupler and proper pump beam diameter under high pump power intensity according to our simulations.     

Numerical Modelling of QCW-Pumped Passively Q-Switched Nd：YAG Lasers with Cr^4＋：yAG as Saturable Absorber

Passively Q-switched quasi-continuous-wave （QCW） diode-pumped Nd：YAG laser with Cr^4＋ ：YAG as saturable absorber is numerically investigated by solving the coupled rate equations. The threshold pump rate for passively Q-switched QCW-pumped laser is derived. The effects of the pump rate and pump-pulse duration on the laser operation characteristics are studied theoretically. The pump power range can be estimated according to the number of output pulses. The numerical simulation results are in good agreement with the experimental results.     

Efficient diode-pumped passively Q-switched laser with Nd:YAG/Cr:YAG composite crystal

Diffusion bonded Nd:YAG/Cr:YAG composite laser crystal has been employed to perform a compact diode-pumped passively Q-switched laser. At the incident pump power of 3.3 W and pulse repetition rate of 16.3 kHz, the maximum average output of 592 mW has been obtained, corresponding to an optical-to-optical conversion efficiency of 18%. Stable passively Q-switched operation with peak power of 6.5 kW and pulse duration of 6 ns was also achieved. It has been experimentally revealed that Nd:host/Cr:YAG composite structure is a promising material for compact cost-effective Q-switched laser sources with high-peak power and short pulse duration. In addition, thermal lens effect (TLE) in the active medium and its impact on the Q-switched laser performance have been analyzed.     

LD side-pumped passively Q-switched Yb:YAG slab laser

A quasi-continuous wave laser diode side-pumped passively Q-switched Yb:YAG slab laser with Cr⁴⁺:YAG saturable absorber has been demonstrated in order to understand the pulse properties of Yb:YAG crystal. To our knowledge the maximum 69% extraction efficiency is achieved by the system. 44 μJ pulse energy and 1.64 KW peak power with near diffraction-limited beam quality are presented at 25 Hz repetition rate. The build-up time of the Q-giant in the passively Q-switched laser is shown.     

Experimental study on passively Q-switched mode-locking diode-pumped Nd:KGW laser with Cr4+:YAG

A diode-pumped passively Q-switched and mode-locked Nd:KGW/Cr⁴⁺:YAG laser with different output couples is realized in a V-type folded cavity. About 85% modulation depth for the mode-locked pulses has been obtained. The repetition rate of the mode-locked pulses inside the Q-switched envelope was about 798 MHz.     

Diode-Pumped Passively Q-switched Single-Frequency Nd:YAG Lasers

Laser-diode pumped passively Q-switched single-frequency Nd:YAG laser has been demonstrated with a Cr⁴⁺:YAG crystal as the saturable absorber. When pumped with a fiber-coupled CW laser diode, the laser produces pulses of 1.4-20.9 ns duration, with a repetition rate of 1.9-52.0 kHz. The highest peak power of 17.6 kW was obtained at an incident pump power of 1.8 W. The use of a Cr⁴⁺:YAG saturable absorber enables the laser to operate not only in a single-frequency mode but also linearly polarized. The mode selection mechanism is discussed.     

Doubly passively Q-switched laser with V<Superscript>3+</Superscript>:YAG and Co:LMA saturable absorbers

By using both V³⁺:YAG and Co:LMA saturable absorbers, a doubly passively Q-switched laser is realized for the first time. The shorter pulse with the higher peak power is generated in comparison to the singly passively Q-switched laser with V³⁺:YAG or Co:LMA saturable absorber. The experimental results shows that it is possible to obtain a shorter pulse with the higher peak power in a doubly passively Q-switched laser.     

A passively Q-switched Yb:YAG microchip laser

We present a diode-pumped passively Q-switched Yb:YAG microchip laser, using a semiconductor saturable absorber mirror. We obtained pulses with 1.1-μJ energy, 530-ps duration, 1.9-kW peak power, and a repetition rate of 12 kHz. The laser is oscillating in a single longitudinal mode. Received: 23 October 2000 / Published online: 7 February 2001     

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.     

High-peak power,passively Q-switched,composite, all-poly-crystalline ceramics Nd:YAG/Cr<Superscript>4+</Superscript>:YAG laser and generation of 532-nm green light

Output performances of passively Q-switched, composite Nd:YAG/Cr⁴⁺:YAG lasers that consisted of bonded, all-poly-crystalline ceramics Nd:YAG and Cr⁴⁺:YAG are reported. Laser pulses at 1.06 μm with 2.5-mJ energy and 1.9-MW peak power are obtained from a 1.1-at % Nd:YAG/Cr⁴⁺:YAG ceramics that was quasi-continuous-wave (quasi-CW) pumped with a diode laser. Single-pass frequency doubling with LiB₃O₅ (LBO) nonlinear crystal at room temperature yielded green laser pulses at 532 nm of 0.36-mJ energy and 0.3-MW peak power, with a conversion efficiency of 0.27.     

Numerical simulation of a CW-pumped Cr:YAG passively Q-switched Yb:YAG pulsed laser

A general model of a CW-pumped passively Q-switched laser is presented which considers the pump power and excitation state of the absorber. The recovery time of the absorber is affected by the Q-switched laser pulse length and repetition rate, which results in changes of the output power, peak power and pulse duration of a CW-pumped passively Q-switched solid-state laser. At low pump power, the final inversion population density alters slowly by a small amount and the effect of the absorber's finite recovery time on laser output energy can be ignored. At high pump power, the final inversion population density increases quickly with pump power increase and the output energy decreases greatly. Simulation results of a CW-pumped, Cr:YAG Q-switched, Yb:YAG laser are reported. The numerical simulation results agree with the theoretical analytical analysis.     

A passively Q-switched diode pumped Yb:YAG microchip laser

A passively Q-switched diode pumped Yb:YAG microchip laser with Cr4+:YAG saturable absorber mirror is reported. The TEMoo laser pulses are obtained with 1,7-uJ pulse energy, 15-ns pulse width, 0.11-kW peak power, and a repetition rate of 2.2 kHz at 1049 nm. The doped concentration and dimension of Yb:YAG microchip crystal are 10 at.-% and 5×0.6 mm2, respectively.     

Diode-end-pumped Nd:YAGLaser with Cr4+:YAG as Passive Q-switch

A diode-end-pumped Nd:YAG laser is passively Q-switched by using Cr4+:YAG as saturable absorber. When CW pumped with a laser diode which the maximum power is 550 mW, the laser produces pulses of 24 ns duration at 1064 nm, with an energy of 26 μJ.     

Diode-pumped doubly passively Q-switched Nd:LuVO4/KTP green laser with Cr:YAG and GaAs saturable absorbers

A diode-pumped doubly passively Q-switched intracavity-frequency-doubling Nd:LuVO₄/KTP green laser with Cr⁴⁺:YAG and GaAs saturable absorbers is demonstrated. This laser can generate the shorter pulse width with higher peak power compared with the singly passively Q-switched green laser with Cr⁴⁺:YAG or GaAs saturable absorber. The relations between the pulse symmetry and the ratio of the small-signal transmissions of two saturable absorbers are investigated. By reasonably choosing the small-signal transmissions of both saturable absorbers, the doubly passively Q-switched green laser can generate the much more symmetric pulse profile. The coupled rate equations are used to simulate the passively Q-switched process of the green laser by considering the Gaussian transversal and longitudinal distributions of the intracavity photon density. The numerical results of the equations are consistent with the experimental results.     

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.     

LBO intracavity frequency doubled, Cr:YAG passively Q-switched Nd:YAG green laser

A LD-pumped, LBO intracavity frequency doubled and Cr:YAG passively Q-switched Nd:YAG green laser was reported in this letter. With 600 mW incident pump laser, Q-switched green laser with average power of 27 mW, pulse width of 15.2 ns, repetition rate of 16.4 kHz and peak power of 108.1 W was obtained.     

A compact passively Q-switched intra-cavity frequency doubled Nd:YAG/Cr4+:YAG composite crystal green laser

A compact diode-end-pumped passively Q-switched intra-cavity frequency doubled Nd:YAG/Cr⁴⁺:YAG composite crystal laser was demonstrated. The pulsed laser at 532 nm was produced and the dependence of the average out power, pulse width and pulse repetition rate on incident pump power were measured. Under the pump power of 14 W, the minimum pulse width of 3.5 ns with repetition rate of 27.5 kHz was obtained, corresponding single-pulse energy of 18 μJ and peak power of 5.3 kW.     

Pulse symmetry and pulse duration compression in a diode-pumped doubly passively Q-switched Nd:YVO4 lasers with Cr4+:YAG and GaAs saturable absorbers

We present a simple technique to improve the symmetry of pulse emitted by doubly passively Q-switched lasers. Using both Cr⁴⁺:YAG and GaAs saturable absorbers in the same cavity, a diode-pumped doubly passively Q-switched Nd:YVO₄ laser is realized for the fist time. This laser can generate more symmetric pulse with shorter pulse width and higher peak power compared with the solely passively Q-switched laser with Cr⁴⁺:YAG saturable absorber or GaAs coupler. The pulse symmetry factor ε of such a doubly passively Q-switched laser is experimentally shown to reach 1.05. Simulations by a rate-equation model for doubly passively Q-switched laser are in close agreement with the experimental results.PACS 42.55.Xi; 42.55.Rz; 42.60.Gd     

Short pulse, high peak power, diode pumped, passively Q-switched 946 nm Nd:YAG laser

We report on generation of 946 nm laser pulses of a few nanosecond duration and up to 3.7 kW peak power from a compact diode-pumped passively Q-switched Nd:YAG laser. This power is 2.5 times as much as what previously has been obtained from this type of a laser. The short pulses with the record high peak power may be particularly attractive for laser range finding type applications.