A Compact all-solid-state slab Nd:YAG laser has been built with MOPA system. The Nd:YAG slab transverse parasitic oscillation is suppression with Sm:YAG absorber The laser pulse time with a pulse duration of 4.87 ns (FWHM) and 2.3 times diffraction limited output beam at a pulse energy of 5.36 J at 1064 nm is achieved without adaptive optics at the repetition rate of 20 Hz.

A high-beam-quality and high-energy long-pulse laser has been developed with VRM(variable reflectivity mirror)coupling and spherical aberration compensation. The thermal lens and the thermal birefringence are compensated for by the 10 mm DL rod side-pumped laser module. The output mirror employs VRM coupling with R=35% in the center, which presents a energy of 1.04 J at a pulse width of 195 mu s and a repetition rate of 400 Hz with a beam quality of M-2=8.4. The spherical aberration compensation improves the beam quality M-2 factor to 2.15; the power stability (RMS) is 0.4% at 5 min, and the optical-optical efficiency is 19.7%.

The amplifier experiment research of end-pumped long pulse slab laser is developed, the results of out-put energy, optical-optical efficiency and pulse waveform are obtained at different experiment conditions, such as peak pumped power, amplifier power and pumped pulse width. The seed laser is CW fundamental transverse-mode operation fiber laser, the laser medium is composited Nd:YAG slab. Under end-pumped and the 2 passes, the laser obtain 7.65J out-put energy and 43.1% optical-optical efficiency with 45kW peak-pumped power and 386μs pump pulse width. The experimental results provide the basic for the optimization design to high frequency, high energy and high beam-quality slab lasers.

A high energy, high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with two amplifier stages is demonstrated. The two-rod birefringence compensation was used as beam quality controlling methods, which presents a short-pulse energy of 40 mJ with a beam quality value of M-2 = 1.2 at a repetition rate of 400Hz. The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns. The method of spherical aberration compensation is improved the beam quality, a M-2 factor of 2.3 and an optical-to-optical efficiency of 27.7% is obtained at the maximum laser out power. The laser obtained 1.4J out energy with polarization integration.

Aiming at the applying demand of airborne laser ranging and laser indication,a compact and reliable electro-optical Q-switched laser was designed.Based on the rate equation with Q-switched,the relationship that the laser output energy increased with the increasing optimization parameter z and the pulse width decreases with increasing z was analyzed.The Nd ∶ YAG laser crystal of φ6.5mm×56 mm,LD side pump,u model of folded cavity which applied cubecorner prism for folding the light,was used as the resonator cavity.The anti-misalignment ability of resonator cavity can be improved under the premise of gain satisfaction.Under the condition of 1.2 J implanted electrical pulse,the energy output of laser single pulse is 108 mJ,the pulse width is 11.8 ns,the energy instability is less than 0.8％ and the light efficiency is 18％,which can be stably operated for a long time.

A high energy,high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MO-PA)laser with two amplifier stages is demonstrated.The two-rod birefringence compensation is used as beam quality control measure,which presents a short-pulse energy of 40 mJ with a beam quality value of M2=1.2 at a repetition rate of 400 Hz.The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns.The method of spherical aberration com-pensation has improved the beam quality,a M2factor of 2.3 and an optical-to-optical efficiency of 27.7% are obtained at the max-imum laser out power.The laser has obtained 1.4 J output energy with polarization integration.

A laser with 60 mm-aperture composite ceramic disk pumped by laser diode arrays was developed. By optimizing waveguide and imaging lens, a pump power peak power of 75 kW, density of 318 W/cm2 is achieved with a pump uniformity of 96% by using a hexagonal waveguide. The temperature distribution and axial deformation of the cooler were optimized, and the axisymmetric micro-channel cooler was designed. Up to 2.3 kW average output power with an optical optical efficiency of 37% is obtained in the stable resonator when pumping with a long-pulse.

建立了包括非热稳定热力学模型、光学传输模型、能量转换模型及非稳腔模型的综合理论分析平台.理论分析得到以下主要结论:谐振腔长度变化对光束质量及光光效率的影响不大,对于给定的增益,激光最佳效率和光束质量分别对应不同的非稳腔放大率.提出非稳腔腔内相位板补偿介质静态畸变提高光束质量的技术措施,并开展实验验证,光束质量由补偿前的5.48倍衍射极限提升到补偿后的2.46倍,输出功率为12.1 kW.

利用ABCD传输矩阵对多片串接正支非稳腔进行分析,给出了谐振腔最优参数,并利用谐振腔自再现条件计算不同薄片上的振荡光束尺寸,根据理想谐振腔阈值条件,得到谐振腔的输出能量.针对上述分析进行了实验验证,在非稳腔放大率为2.0、重复频率为25 Hz、脉宽为250 μs的条件下,输出单脉冲能量为10.52 J,斜效率为22.75％,实验结果与理论设计基本吻合.

High power diode laser vertical stack’s collimated beam pointing error and the influence of the pointing on the laser beam are introduced. The experimental device is built, and single anastigmatic far field lens are adopted to collect the light spot of the vertical stacking. By combining the centroid arithmetic measured continuous work 2 kW vertical stacking diode laser, the results of collimation beam's pointing accuracy was ±1.7 mrad. The errors of the metrical method are analyzed and some routes are optimized to improve the metrical method.

The Nd:YAG slab laser with laser diode array end-pumping experiment has been developed. According to the characteristic of slab medium, the slab laser with image-inverting resonator (IIR) avoids effectively the beam excursion to the slab end and the instability on laser power. It obtains the quasi-continuous laser output with the average power higher than 1000 W when the pump power is 3330 W, the slope efficiency is 42.2%, the stability of the output power is better than 1.5%. The beam quality of laser is measured and the relevant academic analysis is done.

利用Nd:GGG晶体开展了非稳腔的设计研究,通过对抽运系统的优化设计,使抽运均匀性提高到94%;建立了热力学计算模型,计算得到了激光介质的温度分布,实验验证了计算模型的可靠性;利用非稳腔理论分析模型优化了非稳腔的设计参数,实现了输出功率大于10kW、平均光束质量为5.84倍衍射极限的激光输出。

We investigate heat generation in a Nd:YAG thin-disk laser composite with an undoped anti-amplified spontaneous emission (ASE) cap and a side ASE absorber under lasing and nonlasing conditions. The heat load unbalance in three different regions induces a large transverse temperature inhomogeneity under the nonlasing condition. The additional heat fraction generated by the concentration quenching is observed.

建立了侧面抽运板条激光器的热力学模型,对千瓦级侧面抽运Nd:YAG板条激光器的温度和应力进行了数值模拟,并对结果进行了分析。在抽运平均功率3890 W时,侧面抽运Nd:YAG板条激光器获得了1012 W平均功率输出,斜率效率约31%,光-光转换效率约26%。测量了板条侧面的温度,与数值模拟结果吻合较好。

均匀抽运及均匀冷却是激光二极管抽运激光器减小热致光学畸变以实现高光束质量输出的核心技术难题.通过开展键合薄片激光均匀抽运及均匀冷却技术的研究,采用透镜压缩结合波导匀化的设计思想,实现了95%以上的抽运均匀性.同时通过对薄片介质冷却通道的优化设计,实现了优于96%的温度分布均匀性.原理验证实验结果表明薄片介质的波前畸变得到了有效控制,当平均抽运功率密度为230 W/cm2时,忽略离焦效应后介质的反射波前畸变均方根值约为0.35μm.

Thin disk laser is the most successful design to overcome the degradation of the beam quality caused by the gain medium's thermal effects and has many advantages in beam quality keeping and power scalability over the traditional rod and slab laser. In this paper a different type thin disk laser with the large-aperture Nd:YAG disk face-pumped by 2D-stack diode arrays was presented. Over 3kW average power with the beam quality less than 10 times diffraction limitation was achieved by optimizing the pumping optics designs and improving the gain medium mounting technique.

开展了热容激光器光束质量控制研究,进行了耦合系统的优化设计,采用了透镜压缩结合波导匀化的设计思想,使抽运均匀性提高到90%的水平;进一步建立了有源非稳腔的理论分析模型,针对热容激光器的抽运条件开展了非稳腔的优化设计,实验结果表明实现了2.7倍衍射极限的千瓦级热容激光输出.

Diode laser array curvature "smile" produced in the packaging process affects the lasering characteristics,life and beam quality of lasers.Using uniaxial amplification system composed of a high-resolution CCD,a fast axis collimation lens and cylindrical lenses,via laser emitters imaging and facula intensity-based centroid algorithm,the "smile" of diode laser array is measured.The experimental results show that: in the vicinity of threshold current,"smile" of the diode laser array with In solder is less than 2 μm.Influences of FAC lens and CCD resolution on the results are analyzed.

A laser diode (LD)-pumped Nd∶YAG double-disk laser with an average output power of more than 1.5 kW is reported in this paper. A nearly flat top pump profile is achieved with a good design for the four-pass optical coupling system. The disk is coated with Ti, Pt and Au at the back side of the disk which is high-reflectively (HR) coated for the wavelength of the pump and laser radiation, then is welded to the Cu-micro-channel cooler by indium-welding technology. An average output power of 1.52 kW is obtained from two disks with a diameter of 40 mm and a thickness of 1.3 mm. The pumping peak power on each disk is 17.7 kW with duty cycle of 10%. The optical efficiency of the laser system is about 43% and the electrical to optical efficiency is more than 20%.

In order to optimize the operation condition of laser media employed in the heat capacity laser, numerical simulation about temperature distribution and stress distribution within the media are carried out according to different thickness and doping concentration. The principle to optimize parameters of lasing media have been gotten by minimizing the gradient of temperature and stress. Then the pumping coupling way of laser media is analyzed and some current progress in heat capacity laser system is introduced.