A Single-Longitudinal-Mode Dual-Wavelength cw Tm,Ho:GdVO4 Microchip Laser

A liquid nitrogen cooled dual-wavelength Tm,Ho：GdVO4 microchip laser is reported. The output dual wavelengths axe at 2038.9nm and 2050.1 nm. At each wavelength, the laser has a single longitudinal mode. The threshold power is nearly 20mW and the slope efficiency is 18.7%. The single longitudinal mode output power reaches 98mW, and the ratio of power is about 60% （2038.9nm） and 40% （2050.1 nm）.     

High power diode-side-pumped rod Nd:GdVO4 laser

A compact high power diode-side-pumped Nd:GdVO₄ laser has been presented, which can generate an output power of 52 W at 1.063-μm for continuous-wave (CW) operation. The absorption characteristics of the Nd:GdVO₄ in different pump directions is measured, which were used to optimize the diode-side-pumped Nd:GdVO₄ laser head. The laser characteristics of both CW and Q-switched Nd:GdVO₄ and Nd:YAG in are compared and it was found that Nd:GdVO₄ may surpass Nd:YAG for high power laser application.     

Concentration effect of Tm on cathodoluminescence properties of SiO2:Tm and SiO2:Ho,Tm systems

Cathodoluminescence (CL) properties of SiO₂ powders activated with thulium (Tm³⁺) and holmium (Ho³⁺) ions prepared by a sol–gel process were investigated. Different molar concentrations of Tm³⁺ co-doped with Ho³⁺ were studied. The 460 nm peak was monitored and the influence of the beam energy and concentration of Tm³⁺ ions on the emission properties of this peak was also monitored. The peculiar behavior whereby the 460 nm emission peak decreases and the increase in the 705 and 865 nm peaks with the increase in the concentration of Tm³⁺ ions is reported. The relationship between the accelerating beam voltage and the CL intensity of the blue emission peak (460 nm peak) is established. Morphology, particle size and optical properties were characterized with Scanning electron microscopy (SEM), UV/VIS Lambda 750 S spectrometer and Auger electron spectroscopy (AES) equipped with Ocean Optics S2000, respectively.     

Efficient High-Power Ho:YAG Laser Pumped by Dual-End-Diode-Pumped Tm:YLF Laser

We report a Ho:YAG (Ho-doped yttrium aluminum garnet) laser pumped by a dual-end-diode-pumped Tm:YLF (Tm-doped yttrium lithium fluoride) laser to obtain an efficient experimental device with high output-power characteristics. We study the influence of the specific values of the output coupling mirror transmittance, the resonant cavity length, and the radius of curvature of the output coupling mirror on the Ho:YAG laser output characteristics. Under optimum experimental conditions, under which the output coupling mirror transmittance was 30%, the resonant cavity length was 25 mm and the output coupling mirror radius of curvature was 300 mm, and the maximum pumping power of the dual-end-diode-pumped Tm:YLF laser was 15.2 W. We obtain an efficient high-power 2.122-μm laser output of 7.98 W from the Ho:YAG laser. The optical-to-optical conversion efficiency is 52.5%, and the beam quality factor figures are M _x ² ?=?2.89 and M _y ² ?=?2.97.     

High Efficient Continuous-Wave Ho：Y/kG Laser Pumped by a Diode-pumped Tm：YLF Laser at Room Temperature

DUAN Xiao-Ming, YAO Bao-Quan, ZHANG Yun-Jun, SONG Cheng-Wei, GAO Jing, JU You-Lun, WANG Yue-Zhu（ National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001）     

光纤耦合二极管端泵2 μm CW双掺)Tm,Ho∶GdVO4激光器

同YLF和YAG 基质相比,在Tm-Ho∶GdVO₄晶体中Tm³⁺离子在800 nm附近有非常强的和宽的吸收带,所以该晶体非常适合商品化的GaAlAs激光二极管泵浦.在液氮制冷晶体条件下,利用光纤耦合激光二极管及消色差光学耦合系统端面泵浦双掺5％Tm,0.5％Ho∶GdVO₄晶体,在泵浦功率14 W、泵浦波长794 nm时,实现了2.048 μm激光输出,连续运转输出功率3.6 W,相应的光光转换效率为25.7％,斜率效率26.6%.相对于吸收的泵浦功率,光光转换效率为35%.由于Tm³⁺离子间的交叉弛豫效应,泵浦量子效率达到1.3.     

β-NaYF4:Yb,Er/Tm/Ho上转换纳米晶的制备及其水溶性研究

利用低温成核和高温生长的原理, 选用蓖麻油酸(RA)为表面活性剂, 合成了上转换纳米晶β-NaYF₄ :Yb, Er/Tm/Ho.结果表明, β-NaYF₄ :Yb, Er/Tm/Ho纳米晶的粒径约为45 nm, 晶相为纯六方相.在980 nm激发下, β-NaYF₄ :Yb, Er/Tm/Ho纳米晶呈现较强的上转换发光.通过将其溶解在二氯甲烷和水的混合溶液中可知, RA-NaYF₄ 纳米晶只能分散在水中且在暗场下形成明亮的绿光, 而二氯甲烷中没有, 证明其具有良好的水中分散性, 并且在酸性和碱性条件下, 其荧光性能稳定.     

High-power diode-end-pumped CW Nd:GdVO4 laser

We report on a high-power diode-end-pumped CW Nd:GdVO₄ laser. Under the pump power of 39.5 W, a maximum output power of 19.8 W and a slope efficiency of 58.5% were obtained. The beam quality M² at maximum output power was measured to be around 2.62. The thermal focal length in Nd:GdVO₄ crystal under the pump power from 22 to 40.6 W was measured. The pump-induced damage threshold was estimated to be 28.6 kW/cm².     

Resonantly pumped Q-switched Er:GdVO4 laser

We describe a Q-switched Er:GdVO₄ laser resonantly pumped by a MgO-doped periodically poled LiNbO₃ optical parametric oscillator （MgO: PPLN OPO） at 1536 nm. In continuous-wave lasing, the maximum output power is 1.14 W with an incident pump power of 4.7 W and a slope efficiency of 27%. In Q-switched operation, 1.1 mJ of output pulse energy is achieved at 200 Hz. The upper-state lifetime at different pulse repetition frequencies is also calculated.     

A ZnGeP2 Optical Parametric Oscillator with Mid-IR Output Power 3W Pumped by a Tm,Ho:GdVO4 Laser

We report an efficient mid-infrared optical parametric oscillator （OPO） pumped by a pulsed Tm,Ho-codoped GdVO4 laser. The IO-W Tm,Ho：GdVO4 laser pumped by a 801 nm diode produces 20ns pulses with a repetition rate of lO kHz at wavelength of 2.0481μm. The ZnGeP2 （ZGP） OPO produces 15-ns pulses in the spectral regions 3.65-3.8μm and 4.45-4.65μm simultaneously. More than 3 W of mid-IR output power can be generated with a total OPO slope efficiency greater than 58% corresponding to incident 2μm pump power. The diode laser pump to mid-IR optical conversion efficiency is about 12%.     

Spectral characteristics of 2 μm microchip Tm:YVO4 and Tm,Ho:YLF lasers

In this paper, we present experimental results concerning the spectral emission obtained with two microchip lasers emitting in the 2 μm range. We show that high efficiency is achieved in both cases at room temperature. Nevertheless, while Tm:YVO₄ oscillates always on longitudinal modes and may easily be single frequency with high power, Tm:Ho:YLF is always emitting several transverse modes for any pumping conditions with temperatures between 13°C and 35°C. This result is interpreted considering the gain of these two amplifier media and the mode guiding resulting from the thermal properties of the two host materials.     

Passively mode-locked Tm,Ho:YVO4 laser based on a semiconductor saturable absorber mirror

We report the demonstration of passively continuous-wave mode-locking(CWML) of diode-pumped Tm,Ho:YV04 laser using an InGaAs/GaAs multiple quantum-well(MQW) structure semiconductor as the saturable absorber.Stable mode-locking pulses at the central wavelength of 2 041 nm are obtained. The maximum output power is 151 mW.The pulse duration is 10.5 ps at the repetition rate of 64.3 MHz.     

Efficient fourth harmonic UV generation of passively Q-switched Nd:GdVO4/Cr:YAG lasers

A coherent UV passively Q-switched diode pumped Nd:GdVO₄ laser source is proposed. During pumping of the β-BBO crystal a stable light with power 0.6 W with wavelength 532 nm and pulse duration 9 ns at frequency repetition 16 kHz was applied. The output UV light has a power about 79 mW at wavelength 266 nm during diode-pumping with 8 W incident light.     

激光二极管抽运Tm,Ho:YLF晶体声光调Q激光器

对激光二极管端面抽运Tm,Ho：YLF晶体声光调Q激光器的激光特性进行了研究。根据粒子跃迁和能量传递过程,在考虑能级传递上转换的前提下,建立了Tm,Ho：YLF脉冲激光器的速率方程,得到了初始反转粒子数的解析表达式,分析了能量传递上转换效应对激光上能级反转粒子数的影响。在室温下实现了2μm波长激光的脉冲输出。实验上给出并分析了Tm,Ho：YLF脉冲激光器的平均输出功率、单脉冲能量和脉冲宽度随抽运功率以及声光Q开关调制频率的变化关系。在抽运功率为2．8W．重复频率为9kHz时,获得了平均输出功率为189mW的激光脉冲,光-光转换效率为6．8％。在重复频率为1kHz时,得到最大单脉冲能量为65μJ,峰值功率为0．17kW。     

激光二极管泵浦高效Nd∶YVO_4／KTP腔内倍频激光器

报道了激光二极管泵浦的高转换效率Ｎｄ∶ＹＶＯ４／ＫＴＰ腔内倍频激光器。研究了泵浦光斑尺寸、谐振腔长、ＫＴＰ及Ｎｄ∶ＹＶＯ４的温度对输出绿光效率的影响。在输入泵浦功率为６６９ｍＷ时，获得绿光输出功率１５４ｍＷ，光－光转换效率达２３％。     

Up-conversion emission in triply-doped Ho/Yb/Tm KGd(WO4)2 single crystals

Detailed spectroscopic studies of the triply doped KGd(WO₄)₂:Ho³⁺/Yb³⁺/Tm³⁺ single crystals (which exhibit multicolor up-conversion fluorescence) are reported for the first time. The absorption spectra of crystals were measured at 10 and 300 K; the room temperature luminescence spectra were excited at 980 nm wavelength. The dependence of the intensity of luminescence on the excitation power for three different concentration of Ho³⁺, Yb³⁺ and Tm³⁺ ions was investigated. Efficient green and red up-converted luminescence of Ho³⁺ ions and weak blue up-conversion luminescence of Tm³⁺ ions were observed in spectra. The red emission of Ho³⁺ ions is more intensive than their green emission. Dependence of the up-conversion luminescence intensity on the excitation power and impurities concentration was also studied; the number of phonon needed for efficient up-conversion was determined for each case. All possible energy transfer processes between different pairs of the impurity ions' energy levels are also discussed.     

LD-pumped actively Q-switched Nd:GdVO4/KTP red laser

LD-pumped actively Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP red laser has been introduced. A maximum red average output power of 0.78 W at 671 nm was obtained at pulse-repetition frequency (PRF) of 15 kHz and the optical conversion efficiency was 6.5%. At the incident pump power of 12 W, the shortest laser pulse occurred at PRF of 15 kHz. Its full-width at half-maximum and the highest peak power were measured to be 35.8 ns and 3.38 kW. The largest single pulse energy of 56.3 μJ was achieved at PRF of 10 kHz. The influence factors on the Q-switched Nd:GdVO₄/KTP red laser have been discussed.