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.     

LD side-pumped passively Q-switched Yb:YAG slab laser

A quasi-continuous wave laser diode side-pumped passively Q-switched Yb:YAG slab laser with Cr⁴⁺:YAG saturable absorber has been demonstrated in order to understand the pulse properties of Yb:YAG crystal. To our knowledge the maximum 69% extraction efficiency is achieved by the system. 44 μJ pulse energy and 1.64 KW peak power with near diffraction-limited beam quality are presented at 25 Hz repetition rate. The build-up time of the Q-giant in the passively Q-switched laser is shown.     

High-power dual-rod Yb:YAG laser

We describe a diode-pumped Yb:YAG laser that produces 1080 W of power cw with 27.5% optical optical efficiency and 532 W Q-switched with M(2)=2.2 and 17% optical-optical efficiency. The laser uses two composite Yb:YAG rods separated by a 90 degrees quartz rotator for bifocusing compensation. A microlensed diode array end pumps each rod, using a hollow lens duct for pump delivery. By changing resonator parameters we can adjust the fundamental mode size and the output beam quality. Using a flattened Gaussian intensity profile to calculate the mode-fill efficiency and clipping losses, we compare experimental data with modeled output power versus beam quality.     

Optimization of Yb:YAG/Cr<Superscript>4+</Superscript>:YAG composite ceramics passively Q-switched microchip lasers

The laser characteristics of laser-diode end-pumped Yb:YAG/Cr⁴⁺:YAG composite ceramics microchip passively Q-switched lasers were studied by solving the coupled rate equations numerically taking into account the reabsorption of Yb:YAG ceramics at laser wavelength. Effects of the reflectivity of the output coupler, the concentrations and thickness of the saturable absorbers, and pump beam area on the laser performance were investigated analytically. The simulation results of the Yb:YAG/Cr⁴⁺:YAG composite ceramics passively Q-switched microchip lasers were in good agreement with the experimental data. Better laser performance (high peak power, short pulse width and good optical-to-optical efficiency) of the composite Yb:YAG/Cr⁴⁺:YAG ceramics passively Q-switched laser can be obtained by using a thin Cr⁴⁺:YAG ceramic with high concentration, suitable reflectivity of the output coupler and proper pump beam diameter under high pump power intensity according to our simulations.     

Laser-diode pumped heavy-doped Yb:YAG ceramic lasers

Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at.% ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb(3+)-ion lasants.     

Efficient tunable Yb:YAG ceramic laser

A high-power efficient ceramic Yb:YAG laser was demonstrated at a room temperature of 20 °C with an Yb concentration of 9.8 at.%, a gain medium of 1 mm, a pumping power of 13.8 W, an output coupler of T = 10%, and a cavity length of 20 mm. A 6.8 W cw output power was obtained with a slope efficiency of 72%. The ceramic Yb:YAG laser exhibited a continuous tunability in the spectral range of 63.5 nm from 1020.1 to 1083.6 nm for T = 1% at a maximum output power of 1.6 W. To the best of our knowledge, this is the first study of the tunability of ceramic Yb:YAG lasers, except crystal Yb:YAG studies.     

Scalable concept for diode-pumped high-power solid-state lasers

A new, scalable concept for diode-pumped high-power solid-state lasers is presented. The basic idea of our approach is a very thin laser crystal disc with one face mounted on a heat sink. This allows very high pump power densities without high temperature rises within the crystal. Together with a flat-top pump-beam profile this geometry leads to an almost homogeneous and one-dimensional heat flux perpendicular to the surface. This design dramatically reduces thermal distortions compared to conventional cooling schemes and is particularly suited for quasi-three-level systems which need high pump power densities. Starting from the results obtained with a Ti:Sapphire-pumped Yb:YAG laser at various temperatures, the design was proved by operating a diode-pumped Yb:YAG laser with an output power of 4.4 W and a maximum slope efficiency of 68%. From these first results we predict an exctracted cw power of 100 W at 300 K (140 W at 200 K) with high beam quality from a single longitudinally pumped Yb: YAG crystal with an active volume of 2 mm³. Compact diode-pumped solid-state lasers in the kilowatt range seem to be possible by increasing the pump-beam diameter and/or by using several crystal discs.     

Yb:Y2O3透明陶瓷的光学性能研究

介绍了一种基于纳米粉末真空烧结技术的新型固体激光材料——Yb：Y₂O₃多晶陶瓷的制备工艺、物理化学特性、能级结构和光谱特性，并与Yb：YAG单晶进行了对比.采用紧凑型有源镜激光器(CAMIL)的抽运方式，验证了Yb：Y₂O₃透明陶瓷的激光输出性能.在35W的最大抽运功率下，得到波长1078 nm，功率10.5 W 的连续激光输出，斜率效率达到37.5%.实验中还观察到激光输出波长随抽运功率增加而红移以及随输出耦合镜变化而漂移的现象.Yb：Y₂O₃多晶陶瓷是一种理想的激光材料，不仅具有与Yb：YAG单晶同样优秀的物理化学性能和光谱特性，而且其热导率和发射带宽约为Yb：YAG单晶的两倍，非常适合于高亮度激光器和超短脉冲激光器领域的发展应用. 关键词： 2O₃陶瓷')" href="#">Yb:Y₂O₃陶瓷 陶瓷激光器 透明陶瓷     

Hundred mJ, sub-picoseconds, high temporal contrast OPCPA/Yb:YAG ceramic thin disk hybrid laser system

The authors have demonstrated an optical parametric chirped-pulse amplification (OPCPA)/Yb:YAG ceramic thin disk hybrid laser system having hundred mJ level pulse energy sub-picosecond pulse duration with high temporal contrast. At an input chirped-pulse energy of 3.8?mJ from an OPCPA preamplifier an output energy of 130?mJ has been generated from multipass diode-pumped Yb:YAG ceramic thin disk amplifier. A recompressed pulse duration of 450?fs with a contrast level of less than 7.2×10^?9 at ?150?ps before the main pulse has been obtained. The contrast level is the highest value achieved in Yb:YAG chirped-pulse amplification (CPA) laser system at 100?mJ level.     

Optimal design for a diode-pumped high-power high-efficiency high-beam-quality laser

We have demonstrated and analyzed a high-power high-efficiency high-beam-quality continuous-wave (cw) Yb:YAG laser, which is directly pumped into the upper lasing level by a fiber-coupled laser diode with a center wavelength of 969 nm. To achieve high efficiency and high beam quality simultaneously, we carried out a series of comparing experiments by changing the laser-medium length and pump-beam waist radius. From the cw Yb:YAG laser with a 5.0-at.%-Yb³⁺-doped and 5-mm-long crystal, an output power of 19.0 W has been obtained for a pump-beam waist radius of 138 μm. The maximum slope efficiency and optical-to-optical conversion efficiency are 78.9% and 55.3%, respectively. The M² factors of the laser beam are 1.33 in the vertical direction and 1.82 in the horizontal direction.     

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.     

High-power Er:YAG laser with quasi-top-hat output beam

A simple method for simultaneously exciting the fundamental (TEM00) transverse mode and first order Laguerre-Gaussian (LG01) donut mode in an end-pumped solid-state laser to yield a quasi-top-hat output beam is reported. This approach has been applied to an Er:YAG laser, in-band pumped by an Er,Yb fiber laser, yielding 9.6 W of continuous-wave output at 1645 nm in a top-hat-like beam with beam propagation factor (M2)<2.1 for 24 W of incident pump power at 1532 nm. The corresponding slope efficiency with respect to incident pump power was 49%. The prospects of further scaling of output power and improved overall efficiency are considered.     

Diode pumped active-mirror Yb:YAG ceramic lasers

Lasers from Yb:YAG ceramic at different temperature were reported in this paper. The Yb:YAG ceramic laser with active-mirror structure was end-pumped by a laser diode whose central wavelength was 940 nm. At 80 K, with doping concentration of 5 at % Yb:YAG ceramic slab, output energy of 0.68 J at 10 Hz repetition rate was obtained under the pump energy of 2.49 J, corresponding to a slope efficiency of 40% and a conversion efficiency of 27.3%, respectively.     

Laser-diode pumped self-Q-switched microchip lasers

Optical properties of Cr,Yb:YAG, Cr,Nd:YAG crystals, and composite Yb:YAG/Cr:YAG ceramics self-Q-switched solid-state laser materials are presented. The merits of these self-Q-switched laser materials are given and the potentials of such lasers can be chosen by the applications. Cr,Yb:YAG and composite Yb:YAG/Cr:YAG ceramics self-Q-switched laser are conducted. Although several tens of kW peak power can be obtained with a monolithic microchip Cr,Yb:YAG laser, the experimental results show that the performance of this laser is limited by the absorption of Cr⁴⁺ ions at a pump wavelength of 940 nm and strong fluorescence quenching at high Cr concentration. Composite Yb:YAG/Cr:YAG ceramics are more suitable to realize high pulse energy and peak power (up to MW level) with optimized lasing and Q-switching parts. In addition, the instabilities induced by the multi-longitudinal mode competition in Cr,Nd:YAG and Cr,Yb:YAG microchip lasers are addressed. The different gain bandwidths of Yb:YAG and Nd:YAG play an important role in the instability of the output laser pulse trains. Stable laser pulses from the Cr,Yb:YAG microchip laser were obtained due to the antiphase dynamics. For the Cr,Nd:YAG microchip laser, the instability caused by the multi-longitudinal mode competition is an intrinsic property. Different transverse patterns were observed in Cr,Nd:YAG microchip lasers when a pump beam with larger diameter was used. Saturated inversion population distribution inside the gain medium plays an important role in the transverse pattern formation. Different transverse patterns were reconstructed by combining different sets of the Hermite-Gaussian modes.     

Transverse mode control by manipulating gain distribution in a Yb:YAG ceramic thin disk

We demonstrated that transverse mode can be controlled by manipulating gain distribution in a Yb:YAG ceramic thin disk. Several elongated higher order transverse modes of a Hermite-Gaussian beam were observed when a straight-line-shaped gain region was created by using a diode laser output from an optical fiber. An orthogonally crossing pair of straight-line-shaped gain regions created with an additional optical fiber output resulted in the generation of a doughnut-shaped Laguerre-Gaussian beam. This implies that easy and quick switching of Hermite-Gaussian and Laguerre-Gaussian beams is possible without mechanical handling.     

Investigation on the scattering effect of ceramic Nd:YAG

This paper investigates the scattering effect of domestic 0.5 at{\%} ceramic Nd:YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave (CW) Nd:YAG ceramic laser was also demonstrated. A maximum output power of 6.7~W at 1064~nm was obtained at an 808-nm pump power of 32.9~W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd:YAG.     

High-power diode-pumped mode-locked Yb:YAG ceramic laser

A high-power diode-pumped passively mode-locked Yb:YAG ceramic laser was demonstrated. An average output power of 3.80W with a pulse duration of 433 fs at a repetition rate of 90.9MHz was obtained at a wavelength of 1050 nm using a 2% output coupler. A peak power of 96.5kW was also obtained. To the best of our knowledge, these are the highest reported average power and peak power for a diode-pumped mode-locked Yb:YAG ceramic laser.     

Highly efficient 2 μm Tm:YAG ceramic laser

We have experimentally demonstrated a highly efficient diode-pumped Tm:YAG ceramic laser operating at 2 μm wavelength. The maximum output power of 6.05 W was realized with a slope efficiency as high as 65%. As far as we know, it is the highest slope efficiency reported for Tm:YAG ceramic laser. The wavelength tuning experiment of Tm:YAG ceramic laser was carried out and the results suggest that Tm:YAG ceramic laser could operate simultaneously at multiple wavelengths in a wide range of 1884-2017 nm.     

Two-pass amplification of CW laser by Nd/Cr:YAG ceramic Active mirror under lamp light pumping

The concept of an Active mirror with transparent Nd/Cr:YAG ceramics is proposed. A new ceramic material pumped by an arc-metal-halide lamp has been experimentally implemented. CW-laser light generated in a 1064 nm Nd:YAG micro-tip oscillator was amplified by an Active mirror made of Nd/Cr:YAG ceramic and pumped by CW arc-lamp light. The saturation power density of the Nd/Cr:YAG ceramic was lower than that of Nd:YAG because the stimulated-cross-section and lifetime were effectively enhanced by the sensitization of Cr ions. The maximum output laser power while keeping spatial beam quality was up to 3 W with an input lamp power of 9 W; the resulting optical-optical conversion efficiency of 33% was close to the theoretical prediction of nearly 50%.     

4.81 WYb:YAG/1030nm薄片激光器优化设计

设计了四程泵浦的Yb:YAG薄片激光器。晶体掺杂原子数分数为10%,几何尺寸为直径10mm、厚340μm,提出了Cr/Au金属化方案,采用铟焊工艺将其焊接到微通道水冷热沉上。耦合系统为四程泵浦结构,球面镜规格为直径30 mm、曲率半径50 mm。利用LightTools软件模拟计算了泵浦光斑半径,选用曲率半径200 mm输出镜以使泵浦光斑半径与基模光斑半径比符合模式匹配原则。在激光二极管阵列泵浦功率为18.73 W时,获得了最高功率为4.81 W的1030nm连续激光输出,光-光转换效率为25.7%。