Efficient Tm：YAG Ceramic Laser at 2 μm

We demonstrate a high-efficiency continuous-wave Tm： YAG ceramic laser pumped with a Ti：sapphire laser. An output power up to 860mW is obtained under an absorbed pump power of 2.21 W at 785nm, corresponding to a slope efficiency of 42.1% and optical to optical efficiency of 22%. The measured central wavelength is 2012nm.     

Q-Switched Tm：YAG Laser Intracavity-Pumped by a 1064nm Laser

We report a Q-switched 2-μm Tm：YAG laser based on intracavity-pumped by a 1064-nm Nd：YAG laser operating at room temperature for the first time. An average output power of 5.1W is obtained with the repetition rate of 30kHz and a pulse width of 300ns. In addition, we demonstrate a 12.5-W continuous-wave 2-μm Tm：YAG laser, which is, to our best knowledge, the highest power for intracavity-pumping configuration.     

Comment on Q-Switched Tm：YAG Laser Intracavity-Pumped by a 1064 nm Laser

The paper published in Chin. Phys. Lett. 26 （2009） 124211 reported a Q-switched 2-tim Tm：YAG laser that is intracavity pumped by a Nd： YAG laser with emission at 1.06μm. However, analysis of the experimental setup concludes that only the Nd：YAG laser is Q-switched, and the Tm：YAG laser operates in the free-generation regime. Therefore, Q-switch operation for the 2μm emission wavelength is not realized.     

In-Band Pumped High Power Ho：YAG Ceramic Laser by a Tm：YLF Laser

High-power 2 μm lasers are promising candidates for a variety of applications including remote sens- ing, wind lidar, and medicine as well as mid- infrared generation via pumping of optical parametric oscillators. Due to the advantages of low quantum defects and high efficiency, resonantly pumped Ho- doped lasers have attracted great attention. Ho：YAG single crystals have also been widely studied to ob- tain cw and Q-switched laser operation in the 2 μm wavelengths range.     

A Continuous-Wave Ho：YA103 Laser with Output 8.5 W Pumped by a 1.91μm Laser at Room Temperature

A cw high efficient Ho：YAI03 laser pumped by 1.91 μm diode-pumped Tm：YLF laser at room temperature is realized. The maximum output power reaches 8.5 W when the incident pump power is 15.6 W. The slope efficiency is 63.7%, and the Tm：YLF to Ho：YAP optical conversion efficiency is 54.5%. The laser wavelength is 2118.3nm when the transmission of output coupler is 30%. The beam quality factor is M2 -1.39 measured by the traveling knife-edge method.     

A high-power high-stability Q-switched green laser with intracavity frequency doubling using a diode-pumped composite ceramic Nd：YAG laser

We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd:YAG in a straight plano-concave cavity. The temperature distribution in composite ceramic Nd:YAG crystal is numerically analyzed and compared with that of conventional Nd:YAG crystal. By using a composite ceramic Nd:YAG rod and a type-II high gray track resistance KTP (HGTR-KTP) crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd:YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.     

Reply to Comment on ＇Q-switched Tm：YAG Laser Intracavity-Pumped by a 1064 nm Lasers

The essential goal of that paper （Chin. Phys. Lett. 26（2009） 124211） was to obtain a 2μm Tm：YAG laser with short pulse output. A Q-switched technique is used to realize the short pulse output in our laser system. The idea presented by Dr. Nieolaie Pavel is right. In our work, the directly Q-switched 2μm Tm：YAG pulse laser is not realized. As a matter of fact, the Q switch is used to directly switch the 1μm Nd：YAG laser.     

Judd-Oflet analysis of spectrum and laser performance of Ho：YAP crystal end-pumped by 1.91μm Tm：YLF laser

The Ho:YAP crystal is grown by the Czochralski technique.The room temperature polarized absorption spectra of Ho:YAP crystal was measured on a c cut sample with 1 at% holmium.According to the obtained Judd-Ofelt intensity parameters Ω2 = 1.42 × 10-20 cm2,Ω4 = 2.92 × 10-20 cm2,and Ω6 = 1.71 × 10-20 cm2,this paper calculated the fluorescence lifetime to be 6 ms for 5I7 →5 I8 transition,and the integrated emission cross section to be 2.24×10-18 cm2.It investigates the room temperature Ho:YAP laser end pumped by a 1.91 μm Tm:YLF laser.The maximum output power was 4.1 W when the incident 1.91 μm pump power was 14.4 W.The slope efficiency is 40.8%,corresponding to an optical to optical conversion efficiency of 28.4%.The Ho:YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8 nm.     

A Compact High Power Laser-Diode Side-Pumped Tm,Ho：YAG Laser Nearly at Room Temperature with Intracavity Tm：YAG Laser

We report a compact high power Tm,Ho：YAG laser nearly at room temperature. The laser-diode side-pumped Tm：YAG and Tm,Ho：YAG laser modules are operated in the same cavity. The laser yields 37.34 W of continuous wave output power under the temperature of 6℃, corresponding to a maximum slope efficiency of 16.7% when the output power lies from 5.1 W to 27.0 W. This is the first report on the combined Tm：YAG and Tm,Ho：YAG lasers for obtaining high power 2.1 μm laser.     

High efficiency,high power QCW diode-side-pumped Nd：YAG ceramic laser at 1064 nm based on domestic ceramic

A high efficiency, high power diode-side-pumped quasi continuous wave （QCW） Nd：YAG ceramic rod laser at 1064 nm based on the domestic transparent ceramic is reported. The average output power of 961 W is achieved with double ceramic rods by means of a symmetrical convex-convex cavity. The optical-to-optical conversion efficiency is 38.3% and the slope efficiency is 45.3%. To the best of our knowledge, this is the highest level of efficiency achieved for the domestic Nd：YAG ceramic rod laser.     

Mid-infrared optical parametric oscillator based on ZnGeP2 pumped by 2-μm laser

We present a 3 5 μ m optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μ m laser. The tuning curves of ZGP OPO are calculated. The 8 ×6 ×18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7 4.6 μ m, is cut as θ =53.5°, φ =0°. When the pump power of 2.1-μ m polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGP type I phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μ m, respectively. Pulse duration is about 27 ns. Beam quality factor M 2 is better than 1.8. The tunability of 3 5 μ m can be achieved by changing the angle of the ZGP crystal.     

Large-aperture end-pumped Nd：YAG thin-disk laser directly cooled by liquid

A large-aperture Nd:YAG thin-disk laser directly cooled by liquid is end-pumped by two spatial selforganized laser diode arrays. The pump coupling efficiency reaches as high as 93%. Without any complex pump coupling components, the structure becomes simplified and compact. By optimizing the incident angle of the pump beam, a pump power density of 578 W/cm2 is achieved with a pump uniformity of 5.52%. Up to 1 346-W peak output power with a slope efficiency of 54.9% is obtained when pumping with a long pulse. The near-field pattern of the laser output is uniform.     

Passively mode-locked 2-μm Tm：YAP laser with a double-wall carbon nanotube absorber

We report on a diode-pumped passively continuous wave(cw) mode-locked Tm:YAP laser with a double-wall carbon nanotube(DWCNT) absorber operating at a wavelength of 2023 nm for the first time,to the best our knowledge.The DWCNT absorber is fabricated on a hydrophilic quartz substrate by using the vertical evaporation technique.The output power is as high as 375 mW.A stable pulse train with a repetition rate of 72.26 MHz is generated with a highest single pulse energy of 5.2 μJ.     

High-power high-brightness 2-μm continuous wave laser with a double-end diffusion-bonded Tm, Ho：YVO4 crystal

This letter demonstrates an efficient high-power high-brightness 2-μm continuous-wave （CW） laser with double-end, diffusion-bonded Tm, Ho：YVO4 crystal cooled with liquid N2. The reduction in thermal stress in the composite Tm, Ho：YVO4 rod enabled the laser to achieve a laser output power of 23.4 W at 2.05 μm, which is 1.37 times higher than that of the non-composite Tm, Ho：YVO4 rod. The corresponding slope efficiency is 37.3% and the optical optical conversion efficiency is 35.4%. The beam quality M2 factor is about 1.85 at 20 W output level with circularly symmetric beam spot.     

A Graphene-Based Passively Q-Switched Ho：YAG Laser

A 2.09-μm in-band pumped passively Q-switched Ho： YAG laser is demonstrated. Single layer graphene deposited on a quartz substrate is used as the saturable absorber for the Q-switched operation. The minimum pulse width of 2.11μs is obtained at an average output power of lOOmW, corresponding to a pulse repetition frequency of 57.1 kHz and the pulse energy of 1.75 μJ. The beam quality factors M^2 of the Q-switched laser are 1.18 and 1.22 in the horizontal and longitudinal direction, respectively. The optical-to-optical conversion efficiency of the passively Q-switched laser is 4.3%, which is the highest conversion efficiency in the 2 μm wavelength, to the best of our knowledge. It shows clearly that the Ho： YAG crystal is a potential gain medium in the 2 μm range for the graphene application.     

High power diode-side-pumped 1 112-nm Nd:YAG laser based on master-oscillator power-amplifier system

We demonstrate a high power high beam quality diode-pumped 1 112-nm Nd：YAG master-oscillator power-amplifier （MOPA） laser system. To increase the extraction efficiency and output power, a four-pass amplifier scheme is employed. Finally, the injected laser output power is amplified from 26 to 64 W with beam quality factor M2=2.85. Furthermore, a theoretical model that takes the temporal overlap inversion number dynamics into account is employed to analyze the performance of the MOPA laser system, and a good agreement with the experimental data is obtained.     

A Stable 2012.1 nm Single-Longitudinal-Mode Tm：YAG Ceramic Laser with Volume Bragg Grating and Fabry-Perot Etalon

We demonstrate a stable single longitudinal mode Tm：YAG ceramic laser operating at a single wavelength of 2012.1 nm. The single-longitudinal-mode Tin： YAO ceramic laser is obtained by employing volume Bragg grating as one cavity mirror and inserting a Fabry-Perot etalon into the laser cavity. A maximum single longitudinal mode output power of 165roW with a slope efficieney of 6.6% is achieved under the pump power of 5.02 W. The laser has a beam quality of M2 = 1.18 at the maximum single longitudinal mode output power.     

High-peak-power passively Q-switched 1.3 μm Nd:YAG/V~(3+):YAG laser pumped by a pulsed laser diode

We demonstrate a high-pulse-energy, short-pulse-width passively Q-switched(PQS) Nd:YAG∕V3t:YAG laser at 1.3 μm, which is end-pumped by a pulsed laser diode. During the PQS regime, a maximum total output pulse energy of 3.3 m J is obtained under an absorbed pump pulse energy of 21.9 m J. Up to 400 μJ single-pulse energy is realized with the shortest pulse width of 6.16 ns and a pulse repetition frequency of 34.1 k Hz,corresponding to a peak power of 64.9 k W. The high-energy laser pulse is operated in the dual wavelengths of 1319 and 1338 nm, which is a potential laser source for THz generation.     

激光二极管抽运的准三能级2μm(Tm,Ho):YLF激光器的理论研究

根据激光二极管抽运铥,钬(Tm,Ho)共掺激光器中离子之间的能量传递过程,建立了(Tm,Ho)：YLF激光器准三能级的速率方程,对上转换及激光下能级粒子再吸收对激光二极管抽运(Tm,Ho)：YLF激光器运转的影响进行了理论分析,得出了(Tm,Ho)：YLF激光器的阈值抽运功率和斜率效率的解析表达式。并根据所得到的解析表达式对激光器进行了优化设计,分析了增益介质长度、抽运光斑半径、输出镜透过率对激光阈值和斜率效率的影响。并通过实验验证了理论的合理性。同时,对小信号增益进行了详尽的理论分析。