Experimental study of a high power and high efficiency CW diode-side-pumped Nd:YAG laser

This paper reports on the characterization of a diode-side-pumped CW Nd:YAG laser. A side-pumped configuration with 9 laser diodes is used for the laser. Pump light is directly coupled into the Nd:YAG rod without focusing lenses and the pump light distribution in the Nd:YAG rod was calculated. A maximum output power of 150 W in multimode operation is obtained for a pumping power of 400 W. The optical–optical efficiency is 37%. Output power of the laser under different output couplers, resonator lengths and temperatures of the cooling water have been studied.     

High efficiency diode laser side-pumped Nd:YAG rod laser

High efficiency laser performance of 2 mm diameter and 20 mm long Nd:YAG crystal rod transversely pumped by laser diode array is presented. Using the directly side-coupled geometry enclosed by cylindrical pump cavity plated with gold, we obtained long pulse energy of 4.6 mJ corresponding to optical-to-optical slope efficiency of 37%. The complete solid-state Nd:YAG laser is described to be simple, compact and highly efficient. Q-switching of the laser is also reported.     

219.3 W CW diode-side-pumped 1123 nm Nd:YAG laser

We demonstrate a high power continuous wave (CW) diode-side-pumped Nd:YAG laser operating at 1123 nm with a plano-plano configuration. By means of precise coating, a single 1123 nm wavelength is achieved. Under the pump power of 1080 W, an output power of 219.3 W is obtained, which corresponds to an optical-optical conversion efficiency of 20.3%. To the best of our knowledge, this is the highest output power for CW 1123 nm laser based on Nd:YAG crystal.     

Graphene-based passively Q-switched diode-side-pumped Nd:YAG solid laser

In this paper, a desirably simple, convenient and inexpensive saturable absorber mirror has been fabricated based on graphene, which has no wavelength selectivity. Moreover, there are no changes in the structure and characteristics of graphene. By inserting the graphene-PMMA SA mirror to the Nd: YAG laser, the shortest pulse width of 260 ns can be obtained with the single-pulse energy of about 8.32 μJ. The experimental results prove that our graphene-PMMA SA mirror is feasible and suitable for Q-switched lasers.     

1.15 kW连续波全固态Nd:YAG激光器

研制了五组双线二极管列阵侧面泵浦Nd: YAG棒的高效率、高功率激光头。将一块90° 石英旋光片插入两个这样的激光头中间并置入热近非稳对称平平腔，产生了1157 W高光束质量（M2 ~ 39）1064 nm连续波输出，据我们所知，这是侧面泵浦双棒Nd: YAG激光器产生的最高功率。     

468-W CW operation of a diode-pumped Nd:YAG rod laser with high beam quality and highly efficient concentrator of pump light

A novel design of an efficient, highly reliable, and good beam quality diode-pumped solid-state laser for precise material processing application is presented. Effort has been done to obtain a highly uniform pumping intensity in the active area, which simultaneously reduces the effects of thermal gradient. In this design a novel lens duct configuration which send the light into the center of the rod is used. By this way a uniform power distribution and a maximum absorption of pump power is resulted. Adopting this design, the maximum laser power of 468 W with optical to optical efficiency of 33% in CW mode and M² factor of less than 15 is obtained. Numerical analysis also indicates the superiority of the design to other methods such as direct and diffusive pumping techniques.     

A kilowatt level diode-side-pumped QCW Nd:YAG ceramic laser

We demonstrate a kilowatt level Quasi-continuous-wave (QCW) diode-side-pumped Nd:YAG ceramic laser at 1064 nm. The laser system adopts a master oscillator power amplifier scheme (MOPA). The master oscillator contains two diode-pumped laser modules. Under the pump power of 2000 W, an output power of 686 W was obtained. After amplified by an identical ceramic laser module, a maximum output power of 1020 W was obtained under a total incident pump power of 3433 W, corresponding to an optical-optical conversion efficiency of 29.7%. At the maximal output power, the repetition frequency was measured to be 1 kHz and the pulse width was 114 μs. To the best of our knowledge, this is the first time to realize QCW side-pumped Nd:YAG ceramic laser system with output power above 1 kW.     

高功率四波长Nd:YAG激光实验

四波长Nd：YAG激光实验是利用非线性晶体BBO，通过倍频、混频和二次倍频等激光变频技术，分别获取了4个波段相干辐射光，本文介绍了各波长相干辐射光的获取方法及其时空特性的测量。     

647W灯泵浦大功率连续Nd:YAG激光器

 报道了一台灯泵浦大功率连续Nd:YAG激光器。对影响大功率固体激光器模块输出功率和光束质量的主要因素进行了理论分析，并提出提高激光器效率的措施：对聚光腔的形状、结构和材料以及冷却方式，泵浦灯的参数和材料，激光晶体的参数和镀膜进行优化设计，采用径向固定的谐振腔镜。该灯泵浦YAG晶体棒总体电光转换效率为4%，光束质量为22mm·mrad，输出功率647W。     

Pump pulse characteristics of quasi-continuous-wave diode-side-pumped Nd:YAG laser

The influence of pumping laser pulse on the property of quasi-continuous-wave (QCW) diode-side-pumped Nd:YAG laser is investigated theoretically and experimentally. Under remaining a fixed duty cycle, the average output power increases, and the corresponding thermal focal length shorten with the increase of the pump pulse duration, which attributes to the decrease of the ratio of pulse buildup time to the pulse duration. At a pump power of 146 W, the laser output power changes from 65.1 W to 81.2 W when the pulse duration is adjusted from 150 μ s to 1000 μ s, confirming a significant enhancement of 24.7%. A laser rate equation model incorporating the amplified spontaneous emission is also utilized and numerically solved, and the simulated results agree well with the experimental data.     

Pulsed alkali pump light sources for Nd:YAG lasers

Pulsed arc discharges in alkali metal vapours are investigated for use as pump light sources for Nd:YAG lasers. Alkali lamps have a very high radiation efficiency and emit strong lines near the laser pump bands. These absorption bands are fitted by the emission spectrum of sodium and potassium lamps by changing the vapour pressure and input power. The spectral radiation distributions of the lamps are measured by a spectrograph with a gated OMA system. Ray tracing calculations for a laser cavity are used to evaluate the efficiency of the alkali radiation emission for Nd:YAG pumping. The results show that the excitation efficiency of the alkali lamps is twice as high as that of usually used rare gas lamps. For sodium resonance lines the side-on spectral radiance is calculated by a radiation transport model to estimate the pressure and the temperature profile. The results indicate that the alkali vapour lamps could be used as pump light sources with high efficiencies and low heat loading of the laser cavity.     

二极管泵浦Nd:YAG棒双通放大器技术

二极管泵浦NdYAG棒双通放大器采用两个峰值功率6.5 kW激光泵浦模块作为泵浦源.每个激光泵浦模块由81个二极管激光器组成,NdYAG棒直径为6 mm,Nd掺杂质量分数1%.在两个封装方式和结构一致的激光泵浦模块之间采用光学像传递和插入90°石英旋转片进行退偏补偿.在重复频率400 Hz,谐振腔输出单脉冲能量6 mJ时,双通输出400 mJ,激光器光-光转换效率为12.3%,光束质量4.6,脉宽15 ns.     

Experimental study of a high-power CW side-pumped Nd:YAG laser

The paper reports on the characterization of a side-pumped 40 W CW Nd:YAG laser. A side-pumping configuration with six laser diodes is used for the laser. We show the comparison between the calculated and measured pump energy distributions in the laser crystal. The birefringence and the thermal lens effect of the Nd:YAG crystal have been experimentally investigated, and their influence on the performance of the laser are discussed. Output power and beam quality of the laser under different output couplings, cavity lengths, types of cavity and different temperatures of the cooling water have been experimentally studied.     

一种连续Nd：YAG激光锁模的新技术

本文首次报道了在连续运转的Ｎｄ：ＹＡＧ激光器上通过移动腔镜实现锁模的实验研究。获得平均宽度为６０ｐｓ的锁模脉冲序列。文中提出了实验结果的初步解释，表明这种锁模现象是一种增强的自锁模。     

LD泵浦Nd:YAG连续激光器转换性能实验研究

设计了LD端面泵浦固体Nd:YAG连续激光器平台,研究了LD泵浦功率、输出镜透过率和谐振腔腔长对激光器转换性能的影响. 该系统可实现连续1.064 μm近红外激光输出,转换效率可达42.2%.     

High power Nd:YAG slab laser sidepumped by diode laser array

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Relaxation oscillation studies in Nd: YAG laser—Some new results

The study of transient behaviour of a pulse pumped solid state laser system has assumed importance on account of SLM generation by self-seeding with the pre-lase signal. This paper reports on the observations of seed pulses for two different Nd: YAG laser rods, one with anti-reflection coating (AR) on end faces and the other without. The latter displays single longitudinal mode behaviour in each of the relaxation pulse train while the former displays multimode behaviour. Our observations are well explained by the ‘active etalon concept’ introduced earlier.     

Highly efficient diode side-pumped Nd:YAG ceramic laser with 210 W output power

We developed a highly efficient diode side-pumped Nd:YAG ceramic laser with a diffusive reflector as an optical pump cavity. A maximum output power of 211.6 W was obtained with an optical-to-optical conversion efficiency of 48.7%. This corresponds to the highest conversion efficiency in the side-pumped ceramic rod. Thermal effects of the Nd:YAG ceramic rod were analyzed in detail through the measurements of laser output powers and beam profiles near the critically unstable region. A M² beam quality factor of 18.7 was obtained at the maximum laser output power.     

Continuous-wave high-power Nd:YAG-KNbO3 laser at 473 nm

A continuous-wave high-power Nd:YAG laser operating on the ⁴F_3/2→⁴I_9/2 transition at 946 nm and intracavity frequency-doubled to 473 nm by a KNbO₃ nonlinear crystal at room temperature is reported. The Nd:YAG laser outputs a randomly polarized beam of 3.8 W maximum power (38% optical-to-optical efficiency and 44% slope efficiency with respect to the absorbed pump power) at the 946 nm fundamental wavelength. Intracavity frequency-doubling with a 2.0-mm thick KNbO₃ crystal in a linear resonator yielded 159-mW single-ended blue-output with 4.8% optical-to-optical conversion efficiency versus the absorbed pump power. The 473-nm maximum power of 418 mW with 11.6% optical-to-optical conversion efficiency in absorbed power was obtained from a V-type resonator; the overall optical-to-optical conversion efficiency was 6.7%, while the conversion of the available infrared power reached 50%.     

Nd：YAG激光器中的自锁模

本文报道在Nd:YAG激光器中首次获得的自锁模脉冲序列.自锁模是由于Nd:YAG棒中的自相位调制引起的.在主被动对撞锁模运转情况下,自锁模对脉冲波形有较大的影响.