LD泵浦Nd∶GdVO4晶体Cr4+∶YAG被动调Q激光特性研究

考虑腔内光子数密度的空间高斯分布以及晶体热效应的影响,给出了LD泵浦Nd∶GdVO4晶体Cr4+∶YAG被动调Q 1.06 μm激光的耦合速率方程组.数值求解该方程组获得了输出激光的脉冲宽度、重复率、峰值功率以及单脉冲能量随泵浦功率的变化特性,其理论值与实验结果相符.     

Nd:YVO4自受激拉曼激光器调Q锁模特性

利用Nd:YVO4激光晶体的自受激拉曼效应,结合Cr:YAG被动锁模技术和倍频技术,实现了结构紧凑的1176 nm和588 nm黄光锁模激光输出。激光器为LD端面泵浦,三镜折叠腔结构,并且采用了透过率为10%的输出镜。Nd:YVO4晶体长度为10 mm,Nd3+离子掺杂质量分数为0.2%,Cr:YAG晶体的初始透过率为67%。10 W激光泵浦时,1176 nm激光平均输出功率为123 mW,调Q包络宽度为6 ns,调Q包络内的锁模脉冲重复频率高达1 GHz。588.2 nm 黄光的平均输出功率为8 mW。     

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.     

Nd:YVO4自受激拉曼激光器调Q锁模特性

利用Nd:YVO4激光晶体的自受激拉曼效应,结合Cr:YAG被动锁模技术和倍频技术,实现了结构紧凑的1176 nm和588 nm黄光锁模激光输出。激光器为LD端面泵浦,三镜折叠腔结构,并且采用了透过率为10%的输出镜。Nd:YVO4晶体长度为10 mm,Nd3+离子掺杂质量分数为0.2%,Cr:YAG晶体的初始透过率为67%。10 W激光泵浦时,1176 nm激光平均输出功率为123 mW,调Q包络宽度为6 ns,调Q包络内的锁模脉冲重复频率高达1 GHz。588.2 nm 黄光的平均输出功率为8 mW。     

LD-pumped Q-switched Nd:YVO4 self-Raman laser

LD-pumped actively Q-switched Nd:YVO₄ self-Raman laser is presented. The maximum average output power of the self-Raman laser at 1173.6 nm was obtained to be 2.21 W at the incident pump power of 18 W and the pulse repetition frequency (PRF) of 30 kHz, with the corresponding optical conversion efficiency of 12.28%.     

Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm

We demonstrate the first Cr⁴⁺:YAG passively Q-switched c-cut Nd:YVO₄ self-Raman laser at 1168.6 nm based on the Stokes shift of 816 cm⁻¹. At the pump power of 4.7 W, the maximum output power of the Stokes line at 1168.6 nm is 270.5 mW, corresponding to an optical conversion efficiency of 5.8%. The pulse width, pulse repetition rate, pulse energy and peak power are 8.8 ns, 35.8 kHz, 7.6 μJ and 0.86 kW, respectively. At the pump of 5.0 W, the Stokes line at 1097.2 nm based on Raman shift of 259 cm⁻¹ also appears.     

LD泵浦Nd∶LuVO4/Cr4+∶YAG被动调Q激光器

采用大功率半导体激光器端面泵浦Nd∶LuVO4晶体，利用Cr4+∶YAG晶体作为可饱和吸收元件，实现了1.06 μm激光的被动调Q运转.在泵浦功率为19.1 W时，获得最高平均输出功率为4.58 W，脉冲宽度为84 ns，单脉冲能量为36.6 μJ以及峰值功率为436.2 W的激光脉冲.     

Passively Q-switched Nd:GdVO4 solid-state lasers with stabilized repetition rates

By modulating the pump current, we developed a passively Q-switched diode-pumped all-solid-state laser with a repetition rate stabilized up to 10-7. It was experimentally demonstrated that the stability could sustain for an arbitrarily long time. Moreover, the stabilized repetition rates which were synchronized with different modulating frequencies were tuneable in a wide range, by adjusting the period of the pumping cycle only. The output single-pulse energy was also stabilized, which was independent on the pump power after reaching a saturable value.     

Passively Q-switched diode-pumped Cr:YAG/Nd:GdVO4 monolithic microchip laser

The realization of high repetition rate passively Q-switched monolithic microlaser is a challenge since a decade. To achieve this goal, we report here on the first passively Q-switched diode-pumped microchip laser based on the association of a Nd:GdVO₄ crystal and a Cr⁴⁺:YAG saturable absorber. The monolithic design consists of 1 mm long 1% doped Nd:GdVO₄ optically contacted on a 0.4 mm long Cr⁴⁺:YAG leading to a plano-plano cavity. A repetition rate as high as 85 kHz is achieved. The average output power is approximately 400 mW for 2.2 W of absorbed pump power and the pulse length is 1.1 ns.     

Passively Q-switched Nd:LuVO4 laser using Cr:YAG as saturable absorber

A passively Q-switched all solid-state Nd:LuVO₄ 1.06 μm laser was demonstrated by using Cr⁴⁺:YAG as saturable absorber. The characteristics of average output power, pulse width, repetition rate, pulse energy, and peak power were studied with different output couplings and initial transmission of saturable absorbers. When output coupling with the transmission of 20% was used, the shortest pulse width of 16 ns at the repetition rate of 12.5 kHz was obtained, which results in the pulse energy of 71 μJ and peak power of 4.43 kW with the initial transmission of 70% of Cr⁴⁺:YAG crystal.     

Passively Q-switched Nd3+:YAG laser with corner cube

A passively Q-switched Nd3+:YAG laser with corner cube is theoretically and experimentally studied. We analyze the polarization variation in cavity and simulate the peak power, pulse energy and pulse width changed with the rotation angle of corner cube numerically. An experiment is made to verify the theoretical results. With rotating the angle of corner cube about the axis the variation range of peak power is 1.77 MW (from 10.36 to 8.59 MW), and that of pulse energy is 14.9 mJ (from 159.5 to 174.4 mJ), the fluctuation of pulse width is 2.95 ns. The experimental results agree with the theoretical analysis to the extent of variation rules. The most dynamic to static energy ratio of 62.5% is achieved.     

Diode pumped Nd:YAG laser repetitively Q-switched with Cr4+:YAG

Based on the rate equations of passively Q-switched solid state lasers, the performance of laser at a fixed pump power can be optimized through the proper choice of output coupler and the low-intensity transmission of saturable absorber. A simple expression for optimizing these two parameters is derived in this paper. We also demonstrate the performance of an efficient diode-pumpe Cr⁴⁺:YAG passively Q-switched Nd:YAG laser to generate a high-repetition-ate, high-peak power 1064 nm laser pulses, which providing pulses peak power > 10 kW with high repetition rate up to 150 kHz, and the pulse width as short as 6.8 ns.     

Thermal lens measurements in a Nd:GdVO4 self-Raman laser

A method to characterize the thermal lens in a Nd:GdVO₄ self-Raman laser is presented. The thermal focal length was measured to be as short as 180 mm with a self-Raman laser output power of 0.95 W. For comparison, the thermal focal lengths in the cases of fundamental operation and first-Stokes operation were measured experimentally, indicating that the heat generated in the SRS process exacerbated the thermal loading of the Nd:GdVO₄ crystal.     

Pulsed Nd:YAG passive Q-switched laser using Cr4+:YAG crystal

In this paper, we report the experimental results of a pulsed flash lamp Nd:YAG laser at wavelength of 1064 nm and Q-switched by Cr⁴⁺:YAG solid state saturable absorber. We have obtained the output energy (E) and pulse- width (τ_p) of this laser for various initial transmissions of this saturable absorber. Furthermore, the effect of reflectivity of the output coupler (R), diameter of the rod (d), and optical length of the cavity (l) on this laser output data have been investigated. We have used the corner cube as a back mirror, which shows high laser stability and better brightness. We have obtained pulse-width 15 ns with 31 mJ output energy. We have also analyzed this laser theoretically and analytically, which agrees well with our corresponding experimental results.     

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     

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.     

High performance Cr4+:YAG Q-switched CW diode pumped Nd:YAG laser

This paper reports the operation of a Cr4+:YAG Q-switched CW diode laser pumped Nd:YAG at 1064nm. The laser performances resulted in 167 μ J, 21ns pulses at 10kHz, and 1.67W power output. When intracavity polarized, stable amplitude (fluctuations <±1%), TEM00, 153 μ J pulses were generated allowing 50% SHG in KTP. This revised version was published online in November 2006 with corrections to the Cover Date.     

A thermally-insensitive passively Q-switched Cr:YAG/Nd:YAG laser

A passively Q-switched laser with Cr⁴⁺:YAG/Nd:YAG composite crystal using a corner cube prism cavity has been realized, in which the corner cube prism is the key element as it aids the compensation of the thermal lens effect of laser crystal. Compared with plane–plane mirror cavities under the same conditions, the stability of the laser performance using the corner cube prism cavity was improved remarkably over temperatures ranging from −40 to 65 °C. The decrease of Nd:YAG stimulated emission cross section with temperature was considered to be the main reason for the increase of average output pulse energy under the same cycle for the two different cavities when the ambient temperature changed −40 to 65 °C. The mode properties produced by the prism cavity were analyzed, and the theoretical results were verified by experimental observations.     

Pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser

A pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum(FWHM)is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd:YAG/Cr:YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26％(15)through the pre-pumped modulation technique.