Edge-pumped, folded zig-zag Nd:YAG slab laser

 We report the design and performance of conduction-cooled, edge-pumped, folded zig-zag continuous wave Nd:YAG slab laser. The Nd:YAG slab is pumped with waveguide coupled laser diode bars. The coupling efficiency of waveguide to laser diode radiation is 97%. In a folded zig-zag resonator, a maximum output power of 37 W in multimode operation is achieved for an incident pump power of nearly 180 W on the Nd:YAG slab. This corresponds to an optical-to-optical conversion efficiency of 20% and slope efficiency of 32%. We obtained more than 10 W of output power with the beam quality factors in the width dimension and in the thickness dimension equal to 8.     

200-W corner-pumped Yb:YAG slab laser

A novel concept of corner pumping has been developed. The corner-pumped slab design allows long absorption length and symmetric conduction cooling, making it particularly suitable for high-power quasi-three-level lasers. A corner-pumped Yb:YAG slab laser has been demonstrated for the first time. A preliminary experimental result shows that the laser produces 202 W of cw output power with 1400 W of incident pump power. PACS 42.55.Xi; 42.60.Da; 42.60.Pk     

角抽运Nd:YAG复合板条946 nm连续运转激光器

报道了一种适合中小功率输出的全固态激光器的角抽运方法, 抽运光从板条激光器中板条晶体的角部入射, 可获得较高的抽运效率和较好的抽运均匀性.采用单角抽运方式, 首次进行了角抽运Nd:YAG复合板条946 nm连续运转激光器的实验研究. 激光腔采用紧凑型平凹直腔结构, 腔长仅为20 mm. 当注入抽运功率为50 W时, 946 nm激光连续输出功率最高达5.29 W, 光光转换效率为10.6%, 斜效率为12%. 整台激光器结构紧凑, 调谐简单, 成本低, 具有广阔的应用前景. 关键词： 角抽运 Nd:YAG晶体 连续波 946 nm激光     

End-pumped Nd:YAG zigzag slab laser with weak pump absorption

A diode-pumped Nd：YAG oscillator laser with an end-pumped zigzag slab architecture and weak pump absorption is developed. An output power of 253 W with a slope efficiency of 50.2% and an optical-optical conversion efficiency of 39.6% is achieved from the resonator, which emits the maximum power of 290 W with 840-W pump power. An optimum laser diode （LD） array coolant temperature is chosen in an attempt to realize the weak but uniform pump absorption. of zigzag slab resonator depends sensitively on the Furthermore, we have confirmed that the performance incident angle of the beam at the slab end face.     

300 W continuous-wave operation of a diode edge-pumped, hybrid composite Yb:YAG microchip laser

300 W continuous-wave operation of a diode edge-pumped, hybrid (single-crystal/ceramic) composite,Yb3+:YAG microchip laser with a 5 mm diameter and 300 microm thickness single-crystal core uniformly bonded to a water-cooled heat sink by a new Au-Sn soldering system has been demonstrated. The beam quality factor M2 follows the mode mismatch between the core and the fundamental mode and was improved to 17 with a maximum output power of 230 W. A thermally induced convex mirror with a spherical radius of curvature ranging from -2.5 to -1.5 m was observed; the radius of curvature decreases through thermal deformation of the microchip as the pump power increases.     

520-W continuous-wave diode corner-pumped composite Yb:YAG slab laser

We present a pumping scheme for a quasi-three-level solid-state laser. The scheme uses a slab laser configuration with the pump light incident from the slab corners. A diode-corner-pumped composite Yb:YAG-YAG slab laser operating in high-power cw mode was designed to prove the scheme. As much as 520 W of output power was obtained from a single 1-mm-thick composite slab with 0.5-at. %-doped Yb:YAG. The slope efficiency and the optical-to-optical efficiency with respect to the pump power were 32% and 25%, respectively. This result shows the validity of the corner-pumping concept and its feasibility in the development of high-power solid-state lasers.     

角抽运Yb:YAG激光器

报道了一种高功率准三能级激光器角抽运方法，抽运光从板条激光器结构中的板条工作介质的角注入，综合考虑抽运吸收、抽运亮度、晶体的掺杂浓度以及晶体尺寸等因素，进行了角抽运复合Yb:YAG激光器设计，实验上获得了最大连续输出功率400W, 斜效率28%的输出，实验结果充分证明了角抽运原理的正确性和应用于高功率激光器方面的可行性. 关键词： Yb:YAG 角抽运 复合晶体     

Edge-pumped passively Q-switched thin Nd: YAG slab lasers

We report a high-power thin Nd: YAG slab laser with slab dimension of 1×10×60(mm) partially edgepumped by diode laser arrays.Passive Q-switching is achieved with a Cr4 : YAG microchip adopted as the saturable absorber mirror.The pulse duration is around 10ns while the pulse repetition rate is higher than 10kHz.The average output power of 70W is obtained with a slope efficiency of 36%.The diffraction limited beam quality in the thickness direction is obtained by controlling the pump beam diameter inside the slab.The laser head is very compact with size of only 60×74×150(mm).     

1.8 mJ高倍率Nd:YAG板条皮秒激光放大器

设计了一种高倍率的固体皮秒脉冲激光放大器,采用Nd:YAG板条作为激光增益介质。借助板条结构的角度选通结构,搭建了板条五通放大系统,实现了对注入皮秒脉冲激光的高倍率放大。种子源工作在脉冲模式,放大器泵浦源在连续模式工作。皮秒光纤激光器可以在不同的重复频率下工作,脉冲宽度为13.4 ps。种子光经过隔离和耦合系统之后,注入板条的单脉冲能量为25 nJ。当种子源工作重复频率为24.46 MHz时,板条放大器输出平均功率377 W,单脉冲能量15.5 μJ;当种子源工作重复频率为49.8 kHz时,板条放大器输出平均功率89 W,单脉冲能量1.8 mJ,峰值功率为134 MW,放大倍率达到7.2×104。     

High power CW diode-side-pumped Nd:YAG rod laser

We report on the characterization of a diode-side-pumped Nd:YAG rod laser operating at high CW output power. A four-fold pump configuration is designed and the pump light is directly coupled into the Nd:YAG rod without the help of any cylindrical lenses. The distribution of pump light in the Nd:YAG rod has been calculated by using ray tracing program. The thermal lens effect of the Nd:YAG rod has been experimentally measured. A maximum output power of 800 W at 1064 nm in multimode operation is obtained for a pump power of 2400 W with 33% optical-optical efficiency. At the same time, the maximum beam parameter product of 25 mm·mrad is achieved.     

Experimental Study of a Diode-Pumped Nd:YAG Slab Laser Amplifier

We demonstrate a laser-diode-pumped Nd:YAG slab amplifier with dimensions of 7×35×138.2 mm. The fluorescence is homogeneously distributed in the Nd:YAG amplifier, and a stored energy of 3.2 J can be achieved at 1,500 W pump power. For a repetition frequency of 200 Hz, 25 μJ injection polarized seed light, and 1,500 W pump power, the small signal gain reaches 12.66. At the same repetition frequency, 0.4 mJ with 27 ns bandwidth of injected seed-light energy and a 6×26 mm aperture, the output energy reaches 1.071 J. The extraction efficiency is 33.46% after four-pass amplification. An energy amplification from millijoules to joules is realized for the injected laser beam.     

Compact corner-pumped Nd:YAG/YAG composite slab laser

Corner-pumping is a new pumping scheme in diode-pumped all-solid-state lasers, having such advantages as high pump efficiency, favorable pump uniformity and low cost. Compact corner-pumped Nd:YAG/YAG composite slab lasers at 1064 nm with low or medium output powers and high efficiency are demonstrated in this paper. Combined with intracavity frequency doubling by a LBO crystal, a corner-pumped Nd:YAG/YAG composite slab 532 nm green laser with a stable output is realized successfully. The experimental results show that corner-pumping can reduce laser costs greatly, release the thermal effects of slab crystals and improve the output beam quality, and that the new pumping scheme is feasible in the design of diode-pumped all-solid-state lasers with low or medium output powers.     

Optimization of Diode-Pumped Continuous-Wave Tape-Casting YAG/Nd:YAG/YAG-Ceramic Lasers

We demonstrate a diode-laser-pumped solid-state 1.06 μm laser using a novel YAG/Nd:YAG/YAG composite ceramics with a sandwich structure. We optimize the laser performance using different output couplers, pumping beam waists, and cavity lengths. A maximum CW output power of 11 W for the YAG/Nd:YAG/YAG-ceramic laser is obtained at an absorbed pump power of 25 W resulting in a slope efficiency of 49.4%. The excellent output performance shows that the novel YAG/Nd:YAG/YAGceramic material has a great potential in applications with diode-laser pumping.     

High-efficiency composite Tm:YAG laser

A high-efficiency continuous-wave Tm:YAG laser end-diode pumped at room temperature is presented in this letter. The highest output power reaches 6.37 W when the incident pump power is 18.9 W. The optical conversion efficiency is 33.7% and the slope efficiency is 42.8%. The wavelength of the output laser is shifted to the short wavelength with an increase in the transmission of the output couplers. At a fixed cavity length, the composite Tm:YAG shows its dominance for its higher efficiency and higher quantum efficiency compared with the noncomposite Tm:YAG.     

Diode-pumped passively Q-switched YAG/Yb:YAG laser with Cr4+:YAG as a saturable absorber

We design an efficient passively Q-switched laser using a composite YAG/Yb:YAG crystal as the laser gain medium and a Cr⁴⁺:YAG crystal as a saturable absorber. We obtain an average output power of 1.81 W in 1030 nm laser at an absorbed pump power of 4.8 W, corresponding to an optical-to-optical efficiency of 37.7% and a slope efficiency of 47.3%. The pulsed laser has a repetition rate of about 28.6 kHz and a pulse width of 15.8 ns, with the highest peak power of 4 kW. In addition, using a LBO as the intracavity frequency doubler, we obtain a maximum power of 246 mW in 515 nm pulsed laser at an absorbed pump power of 3.8 W.     

Efficient corner-pumped Nd:YAG/YAG composite slab laser

A corner-pumped type is a new pumping type in the diode-pumped all-solid-state lasers, which has the advantages of high pump efficiency and favourable pump uniformity. A highly efficient corner-pumped Nd:YAG/YAG composite slab laser is demonstrated in this paper. The maximal continuous-wave output power of the 1064~nm laser is up to 18.57~W with a slope efficiency and an optical-to-optical conversion efficiency of 44.9{\%} and 39.8{\%}, respectively. Inserting an acousto-optic $Q$-switch in the cavity, the highest average output power of the quasi-continuous wave 1064~nm laser of 6.73~W is obtained at a repetition rate of 9.26~kHz. The experimental results show that a corner-pumped type is a kind of feasible schedules in the design of diode-pumped all-solid-state lasers with low or medium output powers.     

Highly efficient Tm:YAG ceramic laser resonantly pumped at 1617 nm

We report on a highly efficient polycrystalline Tm:YAG ceramic laser in-band pumped by an Er:YAG laser at 1617 nm. Lasing characteristics of 4.0 and 6.0 at.%Tm(3+)-doped YAG ceramics were investigated and compared. With an output coupler of 10% transmission, a maximum output power of 7.3 W was obtained at 2015 nm under 12.8 W of incident pump power, corresponding to a slope efficiency with respect to incident pump power of 62.3%.     

Preparation and characterization of transparent Nd:YAG ceramics

Transparent Nd:YAG ceramics were produced by solid.state reaction of high.purity (4N) nanometric oxides powders, i.e., Al₂O₃, Y₂O₃ and Nd₂O₃. After sintering, mean grain sizes of 2% Nd:YAG samples were about 20 μm and their transparency were a bit worse than that of 0.9% Nd:YAG single crystal. Two types of active elements: rods and slabs were fabricated and characterized in several diode pumping schemes. In end pumping configuration as a pump source 20.W fiber coupled laser diode operating in low duty cycle regime (1 ms pump duration/20 Hz) was deployed. In the best case, 3.7 W of output power for 18 W of absorbed pump power, M² < 1.4 were demonstrated for uncoated ceramics Nd:YAG rod of ϕ 4×3mm size in preliminary experiments. For the ceramics of two times lower Nd dopant level above 30% slope efficiency was achieved. In case of Nd:YAG ceramic slab side pumped by 600.W laser diode stack above 12 W was demonstrated with slope efficiency of 3.5%.     

High-power polycrystalline Er:YAG ceramic laser at 1617 nm

We report on the efficient operation of a high-power erbium-doped polycrystalline Er:YAG ceramic laser at 1617 nm resonantly pumped by a high-power 1532 nm Er,Yb fiber laser. Lasing characteristics of Er:YAG ceramics with different Er3+ concentrations are evaluated and compared. With an output coupler of 15% transmission and 0.5 at. % Er3+-doped YAG ceramic as the gain media, the laser generates 14 W of output power at 1617 nm for 28.8 W of incident pump power at 1532 nm, corresponding to a slope efficiency with respect to incident pump power of 51.7%.     

1064 nm Nd:YAG laser intracavity pumped at 946 nm

We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 885 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. We achieved an output power of 7.97 W at 1064 nm for an absorbed pump power at 946 nm of 9.55 W, corresponding to an optical efficiency of 83.4%. The beam quality M² quality factor is about 1.1 at the maximum output power.