Efficient 532 nm laser using high gray-tracking resistance KTP crystal

A LD end-pumped acoustic-optic Q-switched intracavity frequency-doubled Nd:YVO₄ laser was demonstrated. It uses a high gray-tracking resistance KTP crystal as nonlinear optical crystal. The output characteristics of 532 nm green laser using different doping concentrations and cavity configurations were investigated. With the pump power of 27.5 W, a maximum average power of 13 W at 532 nm was achieved at a pulse repetition rate of 80 kHz, corresponding to the optical-to-optical efficiency of 47.3%. The pulse width is 30 ns and single pulse energy is up to 162.5 μJ. This work is a significant exploration for using a high gray-tracking resistance KTP crystal to generate highly efficient frequency-doubled green laser.     

A compact and high efficiency diode pumped green laser based on MgO doped PPLN

In this work, an efficient intra-cavity second harmonic generation of green laser in a periodically poled MgO doped LiNbO₃ (MgO:PPLN) bulk crystal using a compact Nd:YVO₄ laser as a fundamental laser source is reported. Different length, different working temperature MgO:PPLN crystals are tested and investigated in the SHG experiments. The maximum output power at 532 nm is 6.2 W at the absorbed pump power at 808 nm of 14 W, the optical to optical conversion efficiencies from 808 to 532 nm and 1064 to 532 nm are 43 and 77%, respectively, the instability in 2 hours is less than 5%.     

Compact high conversion efficiency Nd:YAG/LBO green laser using unstable V cavity

We demonstrated a 36.9 W green laser with an intra-cavity second harmonic generation. A compact unstable V type cavity was adopted to compress the whole cavity configuration. The type I phase-matching LiB₃O₅ was used as the nonlinear crystal in the second harmonic generation. The 36.9 W average power and 38 ns pulse width of 532 nm green laser was obtained at a repetition rate of 10.3 kHz, corresponding to a peak power of 94 kW. The optical to optical conversion efficiency from diode to green and from IR to green laser was about 19.8 and 82%, the whole cavity length is about 300 mm. To the best of our knowledge, this is the shortest cavity configuration of side pump green system with output power higher than 30 W and IR to green conversion efficiency larger than 80%. The output fluctuation of this system was less than 3% in 2 h.     

101 W of average green beam from diode-side-pumped Nd:YAG/LBO-based system in a relay imaged cavity

A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.     

Efficient and high-power green beam generation by frequency doubling of acousto-optic Q-switched diode-side pumped Nd:YAG rod laser in a coupled cavity

A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.     

200 W双谐振腔组合单向输出准连续绿光激光器

研究了最大平均输出功率达206 W的高功率准连续绿光激光器.利用ABCD定律及高斯光束在腔内的自再现条件,分析了激光晶体热透镜效应及热致双折射效应对谐振腔稳定性和输出光束质量的影响.实验中将两个型号相同的LD侧面泵浦激光模块分别置于一个平-凹V型谐振腔和一个平-凹直腔内,形成两束稳定运转的1 064 nm基频光,经过声光Q开关和倍频晶体后,产生两束倍频光,均到达平面折叠镜,最终由平面折叠镜单向重叠输出.当激光模块的泵浦电流为50 A,声光调Q的重复频率为22.4 kHz时,最大平均输出功率为206 W,最大单脉冲能量为9.2 mJ,脉冲宽度为201 ns,峰值功率为45.8 kW的532 nm绿光输出,倍频效率达到60.2%.激光器2 h工作的功率不稳定度优于2.5%.     

高功率全固态绿光激光技术研究进展

 报道了高功率全固态腔内和腔外倍频两种绿光激光器研究进展。腔内倍频绿光激光器采用L型腔双棒串接结构,在重复频率10 kHz时,用三硼酸锂晶体倍频获得绿光功率186 W,光-光效率达15.8%。腔外倍频绿光激光器采用主振荡和功率放大器,在重复频率400 Hz时,获得基频激光单脉冲能量1.2 J,采用Ⅱ类相位匹配KTP晶体腔外倍频,获得525 mJ的绿光输出,倍频效率为43.7%。采用偏振合成技术获得了单脉冲能量大于1 J的绿光输出。在该激光放大器实验装置上,进行了双模块热效应补偿技术和受激布里渊散射相位共轭技术实验研究,改善了激光光束质量。     

Continuous-wave passively mode-locked Nd:YVO<Subscript>4</Subscript>/KTP green laser with a semiconductor saturable absorber mirror

A diode-pumped passively mode-locked low-doped Nd:YVO₄ green laser with a semiconductor saturable absorber mirror (SESAM) and an intracavity frequency-doubling KTP crystal is demonstrated. In order to efficiently release the thermal effect, a low-doped Nd:YVO₄ crystal with the Nd³⁺ concentration of 0.1 at % is employed as the gain medium. The maximum average output power of 3.1 W at 532 nm with a repetition rate of 102 MHz is obtained under the pump power of 25 W, corresponding to an optical conversion efficiency of 12.4%. The 532 nm mode locked pulse width is estimated to be approximately 6.1 ps.     

High power and high beam quality CW green beam generated by diode-side-pumped intracavity frequency doubled Nd:YAG laser

We report a stable high power and high beam quality diode-side-pumped CW green laser from intracavity frequency doubled Nd:YAG laser with LBO crystal. By using a advanced resonator, a large fundamental mode size in the laser crystal and a tight focus in the nonlinear crystal could be obtained simultaneously, which are favorable for high power and high beam quality CW green laser generation. The green laser delivered a maximum 532 nm output power of 40 W. The corresponding optical-to-optical conversion efficiency and electrical-to-optical conversion efficiency were 8.6% and 5.0%, respectively. Under 532 nm output power of 34 W, the beam quality factor was measured to be 1.6.     

LD泵浦Nd：YAG/Cr：YAG腔外频率变换高功率紫外激光器

用KTP晶体对激光二极管端面泵浦的Nd:YAG晶体;Cr:YAG被动调Q产生的1064nm脉冲激光器进行腔外倍频,用BBO晶体四倍频产生266 nm紫外激光.用15 W的LD阵列;当LD泵浦功率为12 W的情况下;红外(1064 μm)调Q平均输出功率为2.2 W;脉冲序列周期为40 μs;脉宽为18ns;峰值功率高达4.9kW.采用KTP腔外二倍频;532nm的绿光输出平均功率为850mW;用BBO腔外四倍频;266nm的紫外光输出平均功率高达215mW，绿光-紫外光光转换效率为25.2%, 红外到紫外总的转换效率为9.8%.     

KGW 晶体外腔式高功率579 nm喇曼黄光激光器

报道了579 nm高功率KGd(WO₄)₂喇曼晶体外腔式喇曼黄光激光器的输出特性.基于808 nm脉冲激光二极管侧面泵浦Nd:YAG陶瓷、腔内BBO电光晶体同步延迟调Q和Ⅰ类临界相位匹配的LBO晶体腔外倍频方案,并通过外腔式KGW晶体Ng轴二阶斯托克斯喇曼频移,获得了579.54 nm黄光激光输出.当脉冲信号重复频率为1 kHz、532 nm泵浦光最高平均功率为5.02 W、脉冲宽度为10.1 ns时,获得了最高平均功率2.58 W、脉冲宽度7.4 ns、峰值功率348.6 kW的579.54 nm二阶斯托克斯喇曼黄光激光输出;532 nm至579.54 nm的光-光转化效率为51.4%、斜率效率为54.8%,光束质量因子M_x-579.54²=5.829、M_y-579.54²=6.336,输出功率不稳定性小于±2.35%.实验表明:外腔式喇曼结构能够高效地获得喇曼黄光,具有很高的光-光转化效率及良好的功率稳定性,并通过脉冲LD结合同步延迟电光调Q可获得高重复频率、高平均功率、窄脉冲宽度和高峰值功率的黄光激光输出.     

Stable High Power and High Beam Quality Diode-Side-Pumped Continuous-Wave Intracavity Frequency-Doubled Nd:YAG Laser

We report a stable high power and high beam quality diode-side-pumped cw green laser from intracavity frequency-doubled Nd： YAG laser with KTP. By using a L-shaped concave-convex resonator, designed with two Nd：YAG rods birefringence compensation, a large fundamental mode size in the laser crystal and a tight focus in the nonlinear crystal could be obtained simultaneously. The green laser delivers a maximum 532nm output power of 23.2 W. Under 532nm output power of 20.9 W, the beam quality factor is measured to be 4.1, and the fluctuation of the output power is less than 1.4% in an hour.     

LD泵浦腔外倍频高转换效率Nd3+∶GdVO4固体激光器

通过合理设计精密调控各元件和温控电流，得到了平均功率为70 mW，脉冲宽度为22 ns，重复频率为14 kHz，峰值功率高达230 W的Nd3+∶GdVO4/Cr4+YAG红外脉冲激光器.先采用双凸透镜组合成的望远镜系统对1 063 nm的红外激光进行扩束，再对该光束聚焦，最后经双轴晶体LBO倍频后，得到了平均功率为40.6 mW，脉冲宽度为16 ns，重复频率为14 kHz，峰值功率高达181 W的绿光激光输出，1063 nm→532 nm的转换效率高达58%.测量了532 nm的光谱线宽曲线.解释了该聚焦方法比单一薄透镜效果明显好的原因，并指出了这种聚焦方法的使用对象.     

高效率Nd:YVO4/LBO临界相位匹配脉冲绿光激光器

报道了一种利用激光二极管（LD）端面泵浦Nd:YVO4晶体,声光调Q,LBO临界相位匹配腔内倍频的高效率、小体积、风冷绿光激光器。分析了不同偏振光泵浦的情况下,激光晶体对泵浦光的吸收特性。由分析得出,采用部分偏振光泵浦,可以提高激光晶体对泵浦光吸收均匀性,改善基波畸变,获得高转换效率激光输出。实验中,在泵浦光功率为33 W、声光调Q重复频率为20 kHz时,得到脉宽为23.96 ns、平均功率为15 W的1064 nm基频光输出。经倍频后,得到平均功率为11.2 W的绿光输出,倍频效率为74.6%,总体光-光转换效率为34%。在输出功率为10 W时,测得1 h内输出功率不稳定度为0.512 2%,水平方向和竖直方向的光束质量因子M2分别为1.2和1.1。     

High Electrical-to-Green Efficiency 123 W Average-Power Quasicontinuous-Wave Laser at 532 nm in Compact Design

We present an efficient high-power quasicontinuous-wave (QCW) all-solid-state laser at 532 nm with a simple and compact symmetrical resonator. We design a stable green laser at 532 nm with an average power of 123 W and a repetition rate of 10 kHz by combining a single side-pumped Nd:YAG laser module with a type II LBO crystal for intracavity frequency doubling. The corresponding electrical-to-green conversion efficiency is 12.5%. To the best of our knowledge, this is the highest electrical-to-green efficiency in 532 nm lasers with above 100 W output power ever reported. The pulse width is 62 ns at 123 W, so the peak power is calculated up to 198.4 kW. Such a compact and efficient resonator is promising for integration into laser-application systems.     

Laser diode and pumped Cr:Yag passively Q-switched yellow-green laser at 543 nm

Efficient and compact yellow green pulsed laser output at 543 nm is generated by frequency doubling of a passively Q-switched end diode-pumped Nd:YVO₄ laser at 1086 nm under the condition of sup-pressing the higher gain transition near 1064 nm. With 15 W of diode pump power and the frequency doubling crystal LBO, as high as 1.58 W output power at 543 nm is achieved. The optical to optical conversion efficiency from the corresponding Q-switched fundamental output to the yellow green output is 49%. The peak power of the Q-switched yellow green pulse laser is up to 30 kW with 5 ns pulse duration. The output power stability over 8 hours is better than 2.56% at the maximum output power. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by frequency doubling of a passively Q-switched end diode pumped Nd:YVO₄ laser at 1086 nm.     

All-solid-state intracavity frequency-doubled Nd:Y<Subscript>0.36</Subscript>Gd<Subscript>0.64</Subscript>VO<Subscript>4</Subscript>-GdCa<Subscript>4</Subscript>O(BO<Subscript>3</Subscript>)<Subscript>3</Subscript> green laser under direct 880 nm pumping

We report a green laser at 532 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1064 nm Nd:Y_0.36Gd_0.64VO₄ laser under in-band diode pumping at 880 nm. An GdCa₄O(BO₃)₃ (GdCOB) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 17.8 W, as high as 2.92 W of CW output power at 532 nm is achieved. The optical-to-optical conversion efficiency is up to 16.4%, and the fluctuation of the green output power was better than 2.5% in the given 30 min.     

High-stability single-frequency green laser with a wedge Nd:YVO4 as a polarizing beam splitter

The effect of the large power depletion of the fundamental wave in the phase-matched polarization on the stability of the second-harmonic wave output from an intracavity frequency-doubled ring laser is discussed. It has been demonstrated that the instability resulting from the unbalanced power depletion of the fundamental waves can be eliminated by using a wedge laser rod. The function dependence of the wedge angle and the laser power is concluded. An intracavity frequency-doubled ring laser with a wedge Nd:YVO₄ laser crystal and a LBO doubler is designed and built. Comparing with similar lasers but without using the wedge laser crystal, the frequency-conversion efficiency, the power stability and the polarization purity of the second-harmonic wave output from the laser with a wedge laser rod are significantly improved. The single-frequency green laser of 6.5 W at 532 nm, with the polarization degree more than 500:1 and the power stability better than ±0.3% for 3 h, was experimentally achieved.     

Efficient Nd:Y0.5Gd0.5VO4-KTiOPO4 green laser under diode pumping into the emitting level 4F3/2

We report a green laser at 532 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 1064 nm Nd:Y_0.5Gd_0.5VO₄ laser under diode pumping into the emitting level ⁴ F _3/2. A KTiOPO₄ (KTP) crystal, cut for critical type-II phase matching at room temperature is used for second harmonic generation (SHG) of the laser. At an incident pump power of 17.8 W, as high as 4.21 W of cw output power at 532 nm is achieved. The optical-to-optical conversion efficiency is up to 23.6%, and the fluctuation of the green output power was better than 2.8% in the given 30 min.     

Diode-Side-Pumped Passively Q-Switched Mode-Locked 532 nm Laser with a Nd:YAG/Cr4+:YAG/YAG Composite Crystal

We present a diode-side-pumped Q-switched mode-locked (QML) laser operating at 532 nm for the first time employing a composite crystal Nd:YAG/Cr⁴⁺:YAG/YAG and a KTP. The experimental results show that, using a suitable cavity and crystals, one can obtain high-quality QML laser output at 532 nm with a side-pumped system. We measure and analyze the QML performance of the fundamental frequency laser and the green laser. Under a pump power of 127 W, we obtain a QML laser operating at 532 nm with an average power of 4.97 W and a repetition rate of 0.2 GHz for the mode-locked pulses; the corresponding depth of modulation is close to 100%.