LD-pumped passively Q-switched red laser at 660 nm

A laser diode (LD) pumped Nd:YAG red pulse laser at 660 nm was presented by V:YAG passively Qswitching and LBO intracavity frequency doubling. With 1.6-W incident pump power, average output power of 46-mW, pulse duration (FWHM) of 23.3 ns, pulse repetition rate of 21.6 kHz, peak power of 91.4 W, and single pulse energy of 2.13μJ were obtained. The beam quality factor M2 was less than 1.2. The fluctuations of pulse energy and repetition rate were less than 3% in 4 hours. The pulsed laser at 660 nm is expected to be used as the pump source of Cr3+:doped crystal to obtain the gain-switched tunable laser.     

16.2-W average power from a diode-pumped femtosecond Yb:YAG thin disk laser

We demonstrate a power-scalable concept for high-power all-solid-state femtosecond lasers, based on passive mode locking of Yb:YAG thin disk lasers with semiconductor saturable-absorber mirrors. We obtained 16.2 W of average output power in pulses with 730-fs duration, 0.47-muJ pulse energy, and 560-kW peak power. This is to our knowledge the highest average power reported for a laser oscillator in the subpicosecond regime. Single-pass frequency doubling through a 5-mm-long lithium triborate crystal (LBO) yields 8-W average output power of 515-nm radiation.     

Simultaneous all-solid-state multi-wavelength lasers --- a promising pump source for generating highly coherent terahertz waves

A diode-end-pumped Nd:YAG dual-wavelength laser operating at 1319 and 1338 nm is demonstrated. The maximum average output power of the quasi-continuous wave linearly polarized dual-wavelength laser is obtained to be 2.1 W at a repetition rate of 50 kHz with an output power instability of less than 0.38% and beam quality factor M² of 1.45. Using the two lines, the highly coherent and narrow linewidth terahertz radiation of 3.23 THz can be generated in an organic 4-N, N-dimethylamino--methyl-stilbazolium tosylate (DAST) crystal. Meanwhile, the multi-wavelength red laser at 659.5, 664 and 669 nm is generated by frequency doubling and sum frequency processes in a lithium triborate (LBO) crystal. The average red laser output power is enhanced up to 1.625 W at a repetition rate of 15 kHz with an output power instability of better than 0.53% and beam quality factor M² of 6.05. Using the three lines, it is possible to generate the multi-wavelength THz radiation of 3.3, 3.43 and 6.73 THz in an appropriate difference frequency crystal.     

High-power efficient diode-pumped Nd:YVO4/LiB3O5 457 nm blue laser with 4.6 W of output power

Continuous-wave 457 blue laser emission at powers as high as 4.6 W is achieved by using a fiber-coupled laser diode array with a power of 30 W to pump 0.1 at. % low-doped bulk Nd:YVO4 crystal, with intracavity frequency doubling in a 15 mm long type I critical phase-matched LiB3O5 (LBO) crystal in a compact three-fold cavity with a length of less than 100 mm. The optical-optical conversion efficiency is greater than 15.3%, and the stability of the output power is better than 3% for an hour.     

465 nm laser sources by intracavity frequency doubling using a 49-edge-emitters laser bar

A compact blue laser was generated by intracavity frequency doubling based on quasi-phase-matched second-harmonic generation (SHG) in a MgO-doped periodically poled lithium niobate bulk crystal. A 49 single-transverse-mode edge-emitters laser bar with antireflective coating was used as a pump source. An optical output power of 1.2?W SHG of blue lights at 465?nm is generated at 45?A injection current, equivalent to an overall wall-plug efficiency of 1.33%.     

LD end-pumped intracavity frequency doubling SESAM passively mode-locked picosecond lasers

A diode pumped Nd:YVO₄ semiconductor saturable absorber mirrors (SESAM) passive mode-locked intracavity frequency doubled laser was studied. A type I phase matching LBO frequency doubling crystal was inserted in the cavity. With a pump power of 4.5 W, a 140 mW output of frequency doubled beam was achieved with LBO, while the power of one fundamental frequency beam was 240 mW with repetition rate of 85 MHz, and pulse duration of 5.2 ps.     

456-nm deep-blue laser generation by intracavity frequency doubling of Nd:GdVO4 under 879-nm diode pumping

We report on a simple, compact continuous-wave 456-nm laser by intracavity frequency doubling of an end-pumped Nd:GdVO₄ laser on the ⁴ F _3/2 → ⁴ I _9/2 transition. A 5-mm-long, 0.2-at % Nd:GdVO₄ bulk crystal is employed as the gain medium and the Nd³⁺ ion is directly pumped into the emitting level (⁴ F _3/2) by a novel 879-nm laser diode. Intracavity frequency doubling with a 15-mm-long LBO crystal and a 10-mm-long BiBO crystal in a linear cavity yield 56- and 118-mW single-ended blue outputs at the absorbed pump power of 11.9 W, respectively. The corresponding values are scaled to 286 and 391 mW, respectively, in a V-type cavity, with optical conversion efficiencies of 2.4 and 3.3% versus the absorbed pump power. The fluctuations of the 456-nm output power for both cases are less than 3% at the maximum output level.     

飞秒紫外激光脉冲振荡的实验研究

本文讨论了采用空间光脉冲光谱的啁啾特性和选择聚焦透镜焦距相结合的技术大大提高二次谐波转换效率和产生紫外飞秒光脉冲的实验研究.采用一类相位匹配的BBO晶体,当飞秒钛宝石光脉冲平均功率为560mW时,二次谐波输出功率为352mW,二次谐波转换效率高达63%;采用一类相位匹配的LBO晶体时,获得高光束质量的倍频蓝光输出,输出平均功率为170mW,转换效率大于30%.运用LBO倍频产生的蓝光脉冲和剩余的基频光脉冲进行了三次谐波的振荡研究.三倍频晶体采用BBO,通过优化设计倍频光与基频光之间的空间模匹配及精确时间延迟,得到飞秒紫外光输出,输出功率为2mW,中心波长约为280nm,重复率为100MHz.     

High-power picosecond LiB3O5 optical parametric oscillators tunable in the blue spectral range

The paper reports on an experimental investigation and numerical analysis of noncritically and critically phasematched LiB₃O₅ (LBO) optical parametric oscillators (OPOs) synchronously pumped by the third harmonic of a cw diode-pumped mode-locked Nd:YVO₄ oscillator–amplifier system. The laser system generates 9.0 W of 355-nm mode-locked radiation with a pulse duration of 7.5 ps and a repetition rate of 84 MHz. The LBO OPO, synchronously pumped by the 355-nm pulses, generates a signal wave tunable in the blue spectral range 457–479 nm. With a power of up to 5.0 W at 462 nm and 1.7 W at 1535 nm the conversion efficiency is 74%. The OPO is characterized experimentally by measuring the output power (and its dependence on the pump power, the transmission of the output coupler and the resonator length) and the pulse properties (such as pulse duration and spectral width). Also the beam quality of the resonant and nonresonant waves is investigated. The measured results are compared with the predictions of a numerical analysis for Gaussian laser and OPO beams. In addition to the blue-signal output visible-red 629-nm radiation is generated by sum-frequency mixing of the 1.535-μm infrared idler wave with the residual 1.064-μm laser radiation. A power of 1.25 W of 1.535-μm idler radiation and 5.7 W of 1.064-μm laser light generated a red 629-nm output power of 2.25 W. Received: 2 February 2000 / Revised version: 28 July 2000 / Published online: 22 November 2000     

Violet light generation by frequency doubling of GaAlAs diode laser using a metallo-organic complex crystal ZnCd(SCN)4

Violet 404-nm radiation is generated by type-I single-pass frequency doubling of the output of an GaAlAs diode laser in critically phase-matched ZnCd(SCN)₄ (ZCTC) crystal, a metallo-organic complex crystal. In this paper, its refractive index and second-harmonic generation phase-matching angles are reported. Using a 3-mm-long ZCTC crystal, a diode laser power of 473 mW generated 390 μW of second-harmonic radiation. More recently, 380-nm, 20 μW ultraviolet (UV) radiation is also realized by frequency doubling of the 100 mW output of a continuous-wave Ti:sapphire laser at 760 nm. ZCTC is a promising UV nonlinear optical candidate material for frequency doubling of diode lasers.     

2.41 W compact efficient CW blue light generation by intra-cavity frequency doubling of a compact Nd:YAG laser

We report on a laser diode end-pumped Nd:YAG blue laser using a three-mirror-folded cavity. Three different crystals cut for type-I critical phase matching are used for the intra-cavity frequency doubling of the laser: 10-mm-long LiB₃O₅ (LBO), 15-mm-long LBO, and 10-mm-long BiB₃O₆ (BIBO). Up to 2.41 W of continuous wave output power in the blue spectral range at 473 nm is achieved with BIBO crystal (1.89 W with LBO) at the incident pump power of 16 W, the light-to-light conversion efficiency is about 15.1%.     

High-power ps InGaAs diode laser MOPA system for efficient frequency doubling in periodically poled KTP

This paper reports on a mode-locked InGaAs master oscillator power amplifier (MOPA) system that generates at 920 nm 14-ps-long pulses with a repetition rate of 4.3 GHz and an average power of 2.7 W. Single-pass frequency doubling in a periodically poled KTP crystal provides 550 mW of blue 460-nm radiation. The power of the blue output, which corresponds to a conversion efficiency of more than 20%, was optimized by a detailed investigation of the influence of various system parameters like injection current and repetition rate on pulse power, pulse duration, and spectral shape of the infrared laser pulses. PACS 42.65.Ky; 42.55.Px; 42.72.Bj     

Diode-pumped Nd:LuVO<Subscript>4</Subscript>-LBO green laser at 533 nm

We report a continuous-wave (CW) coherent green radiation at 533 nm by intracavity frequency doubling generation of 1066 nm Nd:LuVO₄ laser. With incident pump power of 18.2 W, output power of 4.3 W at 533 nm has been obtained using a 5 mm-long LBO crystal. The optical conversion efficiency was up to 23.6%. At the output power level of 4.3 W, the output stability is better than 3%. The beam quality M² values were equal to 1.13 and 1.21 in X and Y directions, respectively.     

Watt-level continuous-wave intracavity frequency-doubled Pr:YLF-LBO laser at 320 nm

We report on diode-pumped continuous-wave Pr-doped yttrium lithium fluoride(Pr:YLF) laser and its frequency doubling to320 nm. The maximum output power of the 640 nm fundamental wave reached 3.44 W with a slope efficiency of about 48.3%.Using a type-I phase-matched lithium triborate(LBO) crystal as a frequency doubler, we have achieved 320 nm ultraviolet radiation with a maximum output power of 1.01 W, which is the highest power ever reported under diode pumping, to the best of our knowledge.     

LD端面泵浦Nd:YAG/BIBO单模蓝光激光器

从理论上分析了准三能级系统946 nmNd:YAG全固态激光器运转的条件,并比较了几种不同的倍频晶体的特性,给出内腔倍频获得473 nm蓝光发射的方案。用波长808 nm、输出功率为2.2 W的半导体激光器泵浦Nd:YAG,采用内腔倍频的方法,在一定的温度下,用Ⅰ类临界相位匹配B IBO晶体倍频获得了473 nm 26.5 mW的单模连续蓝色激光输出,功率波动小于±5%。     

20-kHz watt-level green laser with LGS crystal electro-optic Q-switch

A diode-end-pumped electro-optic （EO） Q-switched green laser operating at the repetition rate of 20 kHz is reported. A block of La3Ga5SiO14 （LGS） single crystal is used as a Q-switch and the type I phase- matching LiB305 （LBO） is used as the nonlinear crystal in the second harmonic generation. The 2.3-W average power of 532-nm green laser is obtained at the repetition rate of 20 kHz with the pulse width as short as 10 us. When the output power is about 1.5 W, the measured power fluctuation is less than 1.4% （root-mean-square. RMS） with the beam quality factor of M^2 〈 2 in both orthogonal directions.     

Efficient red light generated by intracavity frequency doubling of a 1331 nm Nd:GGG laser with LBO

We report a continuous-wave (CW) coherent red radiation at 666 nm by intracavity frequency doubling generation of 1331 nm Nd:GGG laser. With incident pump power of 18.3 W, output power of 910 mW at 666 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 910 mW, the output stability is better than 5%. The beam quality M ² values were equal to 1.21 and 1.34 in X and Y directions, respectively.     

Diode-pumped high-power cw blue laser at 473 nm with a compact three-element cavity

We report on a diode-pumped cw Nd:YAG laser operating at 946 nm with a maximum output power of 3.3 W and a slope efficiency of 22% with respect to the incident pump power of 17.5 W. Intracavity frequency doubling with nonlinear crystal LBO yielded a single-ended blue output power of 590 mW with optical conversion efficiency of 3.4%. A very simple, compact three-element cavity of 35 mm long was used. The power fluctuation of the blue laser was 4.3% (rms) at output power level of 400 mW. Transverse mode hopping was observed at higher output power.     

LD泵浦Nd∶YVO4晶体LBO倍频457 nm蓝色激光器

用国产半导体激光二极管泵浦Nd∶YVO4晶体,在室温下获得914 nm激光连续输出，用Ⅰ类临界位相匹配LBO腔内倍频获得457 nm蓝色激光输出.当泵浦注入功率为1.7 W时倍频蓝激光最大输出达20 mW，光光转换效率为1.2%,功率稳定性24 h内优于±3%.     

4.7-W, 255-nm source based on second-harmonic generation of a copper-vapor laser in cesium lithium borate

We have generated 4.7 W of UV (255-nm) radiation with wall plug efficiency of 0.12% by frequency doubling the green (511-nm) output of a kinetically enhanced medium-scale copper-vapor laser (CVL) in cesium lithium borate (CLBO). Frequency doubling in beta -barium borate produced 3.9 W of UV radiation with wall plug efficiency of 0.1%. We found that conversion was better with CLBO because of the reduced constraints on CVL beam quality, less UV absorption, and smaller UV walk-off.