Modeling the pulse shape of Q-switched lasers to account for terminal-level relaxation

To account for the effect of lower-level relaxation,we have derived a characteristic equation for describing the laser pulse from the modified rate equations for Q-switched lasers.The pulse temporal profile is related to the ratio of the lower-level lifetime to the cavity lifetime and the number of times the population inversion density is above the threshold.By solving the coupled rate equations numerically,the effect of terminal-level lifetime on pulse temporal behaviour is analysed.The mode is applied to the case of a diode-pumped Nd:YAG laser that is passively Q-switched by a Cr 4+:YAG absorber.Theoretical results show good agreement with the experiments.     

LD泵浦355nm准连续紫外激光器

报道了一台LD侧面泵浦Nd:YAG晶体的内腔三次谐波转换的全固态准连续紫外激光器。在谐振腔内,1064nm的基频波通过对Ⅱ类相位匹配KTP晶体进行二倍频来产生532nm波长激光,二者再通过对Ⅱ类相位匹配LBO晶体进行和频来获得355nm紫外激光输出。355nm全固态紫外激光器在声光调Q重复频率为2.8kHz下,当输入电流为18A时可得到503mW的激光输出。     

Passively Q-switched self-frequency doubling Nd:Ca4GdO(BO3)3 laser with Cr:YAG saturable absorber

Nd³⁺ : Ca₄GdO(BO₃)₃, known as Nd : GdCOB, is a new self-frequency doubling laser crystal. Using Cr⁴⁺ : YAG as passive Q-switch, we have realized the Q-switched laser running at 0.53 μm with an Nd : GdCOB crystal. Meanwhile, the pulse width, the single pulse energy and the repetition rate under different small-signal transmission of Cr⁴⁺ : YAG and different pump conditions are measured and the numerical solutions of the coupling wave rate equations agree with the experimental results.     

用预泵浦技术实现Cr4+、Nd3+双掺YAG激光器自调Q可控输出

对LD泵浦Cr⁴⁺、Nd³⁺双掺YAG自调Q激光器进行了研究,在连续泵浦和脉冲泵浦下获得了1.064μm调Q偏振激光脉冲输出,脉冲宽度(FWHM)为30ns,单脉冲能量为0.5μJ.采用直流预泵浦技术使Q开关时间的不确定度从×10ms减小到5μs左右,并使激光Q脉冲重复率从1kHz提高到近17kHz,该方法也同样适用于其它被动调Q激光器.     

低温生长GaAs在Nd∶YVO4激光器中调Q特性的研究

采用一种新型的被动调Q饱和吸收体,低温生长GaAs薄膜，实现了半导体抽运Nd∶YVO4激光器的调Q运转.研究了激光器的调Q特性,调Q抽运阈值为2W.在抽运功率9.2 W时，获得的最短脉冲半峰全宽为15 ns，最大单脉冲能量为4.84 μJ，最高峰值功率为330 W，最大平均输出功率为1.16 W；脉冲重复频率在220 kHz到360 kHz之间.     

被动调QNd:YAG/Cr:YAG微晶片激光器的优化设计与实验

用数值求解速率方程的方法对被动调Q微晶片激光器进行了优化设计,并在实验中验证了这一优化效果。首先对速率方程进行数值求解,从数值求解的结果中得出了几个关键性参数,例如可饱和吸收体的初始透过率、输出镜反射率、激光器腔长、激光器腔内损耗、抽运激光光斑大小等,给出了关键性的参数对被动调QNd∶YAG/Cr∶YAG激光器的影响;然后基于数值求解的结果对微晶片激光器进行了优化设计,例如缩短激光腔长度,减小腔内损耗,选择合适的输出镜反射率、初始透过率和抽运激光光斑大小等;最后完成了两种不同参数的微晶片被动调QNd∶YAG/Cr∶YAG微晶片激光器的制作。     

LD-pumped single-frequency passively Q-switched green laser

A LD-pumped single-frequency passively Q-switched Nd: YVO₄/KTP/Cr:YAG green laser is presented. Cr:YAG plays the double role of a passive Q-switch and a Brewster plate. With 900 mW incident pump laser, single-frequency passively Q-switched green laser with average power of 86 mW, pulse width of 14.7 ns, repetition rate of 140.8 kHz and peak power of 41.6 W is obtained. Measurement shows that the pulse amplitude and period between pulses are stable within ±1.5%.     

Experimental Study on Flashlamp Pumped Nd3+∶KGd(WO4)2 Laser

The lasing properties of Nd∶KGW crystal in free-running mode with different transmission of the output couplers are reported.The best results have been obtained with the output coupler of 24% transmission.The slope efficiency is 1.0% and the extrapolated energy threshold is 0.54 J.A comparative experiment of Nd∶KGW and Nd∶YAG laser crystals has been cavried out under identical experimental conditions in both free-running and Q-switched modes.The much higher efficiency and the lower threshold for Nd∶KGW (Nd: 2.2 at.-%) compared to Nd∶YAG (Nd: 1.1 at.-%) at 1.064 μm are demonstrated in both operation mode.     

氧化石墨烯被动调Q掺铒光纤激光器

报道了基于氧化石墨烯的被动调Q掺铒光纤激光器。激光器采用环形腔结构,调Q器件为自制的氧化石墨烯可饱和吸收镜。泵浦功率在81~505 mW范围内时,得到了重复频率68~124 kHz的稳定的调Q脉冲输出,脉宽为0.47~1.60 s。由于泵浦功率限制,激光器最大输出功率为10 mW, 相应单脉冲能量为80.6 nJ。此种基于氧化石墨烯可饱和吸收体的被动调Q光纤激光器体积小、成本低廉、结构简单、稳定性高、光束质量高,具有广阔的应用前景。     

A diode end-pumped passively Q-switched Nd:YAG/KTA Raman laser

A diode end-pumped passively Q-switched Nd:YAG/KTA intracavity Raman laser is presented. A KTA crystal with a size of 5 mm × 5 mm × 25 mm is used as the Raman active medium and its 234 cm^?1 Raman mode is employed to finish the conversion from 1064 nm fundamental laser to 1091 nm Raman laser. A 2 mm thick Cr⁴⁺:YAG crystal is used as the saturable absorber. With an LD pump power of 7.5 W, the first-Stokes power of 250 mW is obtained with a pulse repetition frequency of 14.5 kHz. The corresponding diode-to-Stokes conversion efficiency is 3.3% and the pulse energy is 17.2 μJ. Pulse width is measured to be 12.6 ns and peak power is 1.4 kW.