Performance of CW NYAB laser at 1.06 μm end-pumped by a high-power diode-laser-array

A CW NYAB laser at 1.06 μm end-pumped by a high-power diode-laser-array has been demonstrated. At the incident pump power of 11 W, a maximum output power of 3.2 W was achieved, resulting in an optical conversion efficiency of 29.1%, and average slope efficiency of 37.5%. The output beam quality factor was measured to be M²=1.9. The internal losses caused by the NYAB crystal were measured to be 0.035 cm⁻¹. The NYAB crystal was also found to exhibit very strong thermal lensing under high-power end-pumped conditions.     

Compact high-power end-pumped Nd:YAG laser

We present a compact diode- and end-pumped Nd:YAG laser for material processing with an output power of 238 W, an optical-to-optical efficiency of 48% and a slope efficiency of 60%. This is to the best of our knowledge the highest optical efficiency for a high-power end-pumped Nd:YAG laser.     

Passively Q-switched Self-frequency Doubling NYAB laser with GaAs Saturable Absorber

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Passively Q-switched Self-frequency Doubling NYAB laser with GaAs Saturable Absorber

By using a passive Q-switch with GaAs saturable absorber, the Q-switched self-frequency doubling NYAB laser at 0.531μm has been successfully realized. The pulse width and the single pulse energy are measured. The numerical solutions of the coupling wave rate equations are in agreement with the experimental results.     

Control of the pulse width of a laser-diode end-pumped passively Q-switched solid-state laser

We theoretically and experimentally study different techniques to control the pulse width of a laser-diode-pumped passively Q-switched solid-state laser. It is shown that varying the laser beam radius in the saturable absorber and the pump beam radius in the gain medium provide an efficient means to control the pulse width. The experiments performed on a laser-diode-pumped Nd:YVO₄ laser passively Q-switched by a Cr⁴⁺:YAG saturable absorber are consistent with the theoretical calculations obtained from the rate-equations model, in which the intracavity photon density is assumed to be Gaussian spatial distribution, and the longitudinal variation of the intracavity photon density and the pump beam spatial distribution are also considered.     

Transient temperature profile in the gain medium of CW- and end-pumped passively Q-switched microchip laser

The transient temperature profile in CW- and end-pumped passively Q-switched (PQS) microchip laser is investigated qualitatively by treating the population inversion (thereby the thermal load) as the sawtooth function of the time. The numerical results reveal not only the dynamics of thermal buildup, but also the dependence of the quasi-steady-state temperature rise and the repetitively oscillatory amplitude on the incident pump power and the pulse repetition rate of PQS laser. The abruptly ascending branch of the repetitive temperature oscillation is synchronized with the pulsing stage of PQS laser. As the result, the abrupt temperature transition during the pulsing stage would introduce the fluctuation into the PQS pulse parameters (pulse energy, pulse width, and peak power) via temperature-dependent stimulated emission and thermal lensing effect.     

氙灯泵浦的NYAB晶体调Q激光运转特性及实验研究

首次报道了氙灯泵浦的自激活自倍频NYAB复合功能晶体的BDN染料片调Q运转,获得了自倍频绿光单脉冲.测量了不同L和T_o情况下的绿光脉冲的能量、脉宽和峰值功率.文中还从理论上推导了自激活自倍频晶体调Q激光器的方程组.数值求解方程组,所得的理论数据与实验结果很好地相符.最后,讨论了进一步提高绿光脉冲峰值功率的途径.     

Thermal modeling of the continuous-wave end-pumped Q-switched lasers

The transient temperature profiles in continuous-wave (cw) end-pumped Q-switched lasers are investigated by solving a numerical model coupling the transient heat conduction equation and the rate equations, in which the influences of the thermal time constant, the fluorescence lifetime and the repetition rate on the temperature variation are considered. Furthermore, the buildup dynamics of thermal equilibrium in several laser crystals are presented and compared with each other. The numerical simulation results reveal that the buildup time of thermal equilibrium mainly depends on the thermal time constant, however, the temperature rise is primarily influenced by the absorption cross section. Compared with the influences of the other parameters, fluorescence lifetime principally determines the thermal oscillation contrast. In addition, it is also found that the repetition rate and the pump power have significant effects on the thermal characteristics in Q-switched lasers.     

Highly efficient and compact laser-diode end-pumped Q-switched Nd:YVO4/KTP red laser

A laser-diode end-pumped acousto-optic (AO) Q-switched Nd:YVO₄/KTP red laser by using a plano-concave cavity was demonstrated for the first time. This linear cavity configuration could guarantee not only moderate intracavity focusing on KTP crystal but also good beam quality. Under the absorbed pump power of 14.8 W, the maximum average output power at 671 nm was obtained to be 1.37 W at the repetition frequency of 15 kHz, with the corresponding optical conversion efficiency of 9.3% and the pulse width of 33 ns. The energy of a single pulse and corresponding peak power are estimated to be 91.3 μJ and 2.77 kW, respectively. The rate equations are also numerically solved by introducing the nonlinear loss resulting from generation of second-harmonic wave.     

1.6 W of TEM00 cw output at 1.06 μm from Nd:CNGG laser end-pumped by a fiber-coupled diode laser array

In this paper we demonstrated and analyzed a high-power cw Nd:CNGG laser end-pumped by a fiber-coupled diode laser array in a convex–concave-type cavity. TEM₀₀ mode output power of 1.63 W was obtained with 27% optical-to-optical conversion efficiency and slope efficiency of 44.5%. Thermal lensing and its variation with the incident pump power for this crystal have been measured. The coefficient for pump power induced diffraction losses of Nd:CNGG crystal have also been estimated for this laser configuration.     

LD泵浦高功率高斜效率Nd:YVO4声光调Q激光器

 报道了采用激光二极管(LD)端面泵浦Nd:YVO₄双端键合晶体高平均功率高斜效率1 064 nm声光调Q激光器。通过对大功率泵浦情况下激光晶体热透镜效应进行分析和估算,优化了模式匹配及热稳腔结构参数,实现了稳定的高功率高斜效率准连续脉冲激光输出。在泵浦功率46.8 W、最高重复频率50 kHz下,获得最大平均输出功率17.6 W,光-光转换效率为37.6%,斜效率达70.1%,脉冲宽度51.3 ns;在最低重复频率10 kHz下,获得最大单脉冲能量0.91 mJ,峰值功率为46.2 kW,脉冲宽度为19.8 ns。     

激光二极管泵浦NYAB激光器的空间分布速率方程的研究

报道了用以描述激光二极管泵浦ＮＹＡＢ连续激光顺空间分布特性的非线性耦合的速率方程组，和以此方程组进行的理论计算，讨论了泵浦光和激光的空间分布、晶体的最佳长度、输出镜的最佳透过率对激光器输出的影响，给出了ＮＹＡＢ激光器设计的一些依据。     

Continuous-wave diode-laser end-pumped Nd:YVO4/KTP high-power solid-state green laser

A simple folded-cavity used for intracavity frequency-doubled Nd:YVO₄ laser was analyzed by transmission matrix and numerical calculation. We have selected a set of proper cavity parameters which can be used readily by operating at high power levels with low threshold, high efficiency, and wide dynamic operating range. 5.6-W TEM₀₀ green laser has been obtained at a 22-W pumping power and with an optical–optical conversion efficiency of 25.5%.     

被动调Q激光器优化的研究

被动调Q激光器以其结构简单、紧凑而获得了广泛的应用。为优化其性能参数,在总结近些年被动调Q基本理论基础上,对于具有能量上转换(Energy-transfer upconversion)的激光工作物质构成的被动调Q激光器,提出了可以将能量上转换引起的损耗归到线性损耗中进行优化设计的方法,并给出了输出镜的反射率和饱和吸收体的小信号透过率两者优化选择的直接关系图。根据被动调Q激光器的特有参数α,在总结提高调Q峰值功率的方法基础上,得出当α接近无穷大时,从被动调Q过渡到主动调Q,实现了被动调Q和主动调Q理论的统一。     

非线性激活复合功能晶体NYAB激光器理论及实验研究

本文对非线性激活复合功能晶体激光器提出了一种新的理论模型.该模型采用慢变波近似,建立了耦合波-速率方程;并利用计算机对复合功能晶体NYAB激光器进行模拟,得到理论结果;并讨论了阀值及峰值功率.实际上采用波长为589nm巨脉冲激光泵浦,对(Nd_xY_(1-x)Al_3(BO_3)_4)NYAB激光器激光复合效应进行了研究,获得自倍频绿光输出峰值功率达37.5kW.理论与实验结果符合得较为满意.最后对理论模型与实验的偏差,探讨了一些改进器件设计的途径.     

磷玻璃宽带调Q激光器

本文提出采用两片尖峰简并型共振反射器作为磷玻璃振荡器的耦合输出镜,利用其反射调制包络特性,实现了带宽100(?)的激光输出方案,并获得了成功,实验分析了宽带输出特性.     

调Q钕玻璃激光器宽频带倍频

本文描述了宽频带激光非线性相互作用耦合方程,并在Δλ(FWHM)=60的钕玻璃调Q激光系统上对不同类型倍频器进行宽频带倍频的实验研究。实验结果与理论计算符合得很好。     

Dual-polarization electro-optical Q-switched ceramic laser

A dual-polarization electro-optical Q-switched Nd:YAG ceramic laser was studied. By selecting the appropriate size of calcite crystals, the dual-polarization Q-switched pulse was achieved by characteristics of calcite crystal. Experimental results show that compared with the traditional single-polarization electro-optical Q-switched laser, insertion loss is reduced, dynamic to static ratio is greatly improved, thermally induced birefringence of electro-optical Q-switched Nd:YAG ceramic laser is effective compensated. The output power of 19 W and the pulse width of 13 ns are obtained at the repetition rate of 1 kHz and pumped power of 144 W. The dynamic to static ratio is 71%. The results formed the basis for the further development of the high power and high efficiency ceramic red laser.     

高功率LD阵列泵浦激光器小型化研究

为满足一些武器装备对激光系统小型化及输出激光光斑均匀性较高的要求,通过设计LD侧面对称半环状泵浦的泵浦方式,使得输出的激光光斑形状基本为圆形,激光光斑的均匀性有了较大提高.采用凹面全反射镜补偿热效应以及设计紧凑激光谐振腔型,在注入电流60 A、频率为20 Hz时,得到平均单脉冲能量为96 mJ (脉冲能量波动小于6%)、脉宽为10 ns、发散角为3 mrad的近似圆形激光输出,激光系统在高温50℃时工作稳定.     

石墨烯可调谐被动调Q掺铒光纤激光器

基于光学沉积方法,制备了石墨烯可饱和吸收体,并利用此可饱和吸收体搭建了环形腔结构的被动调Q掺铒光纤激光器,实现了稳定的调Q激光脉冲输出,其重复频率为5.1~14.2 kHz,最窄激光脉冲宽度为8 s,最大平均功率为162.3 W,且通过调节偏振控制器,中心波长在1556~1558 nm可调。