High power continuous-wave diode-laser-pumped Nd:YAG laser

We report on a diode-laser-pumped cw Nd: YAG laser operating at a power level of 150 W. By using a transverse pump geometry, the radiation of 54 diode lasers with an output power of 10 W each is coupled into a Nd:YAG rod. In multimode operation, an optical slope efficiency of 32% and an optical to optical efficiency of 29% are obtained. In TEM₀₀ operation, an output power of more than 30 W is realized with an optical to optical efficiency of 10%.     

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.     

The first-stokes pulse generation in Nd:KGW intracavity driven by a diode-pumped passively Q-switched Nd:YAG/Cr<Superscript>4+</Superscript>:YAG laser

The operation of an all solid-state pulsed Nd:KGW Raman laser pumped by compact passively Q-switched Nd:YAG/Cr:YAG laser is demonstrated. The first-Stokes radiation of stimulated Nd:KGW Raman scattering at the 1178 nm is generated. The average output power of 336 mW at Stokes wavelength was obtained under the laser diode pump power of 5.74 W. The corresponding optical efficiency from the diode light to the Raman output is 9.85%. The pulse width of 1.65 ns and a pulse repetition rate of 10 kHz were also obtained.     

Littrow-type discretely tunable, Q-switched Nd:YAG laser around 1.3 μm

An all-solid-state, side diode array pulse pumped Nd:YAG laser tunable for six wavelengths ranging from 1318.8 nm to 1356.0 nm is developed. The tunability is obtained by using a grating in Littrow mode that also serves as an output coupler. The configuration ensures a line width as low as 0.04 nm. Thermal effects limit the maximum average power to 250 mW for an average absorbed pump power of 8.0 W in the free-running condition. An acousto-optic Q-switching of the laser provides pulses of width 251 ns with peak power of 733 W for an average pump power of 11.5 W. The laser may find application in microsurgery and dermatology. PACS 42.55.Xi; 42.60.-v; 42.60.Fc; 42.60.Gd; 42.62.Be     

Compact TEM<Subscript>00</Subscript> grazing-incidence Nd:GdVO<Subscript>4</Subscript> laser using a folded cavity

A compact diode-side-pumped Nd:GdVO₄ laser system using a folded cavity and grazing-incidence configuration is presented. The highest multimode output power obtained was 21.8 W at 36 W of effective diode pump power. Highest optical-to-optical conversion efficiency of 61.5% was achieved at 33 W of effective diode pump power with 20.3 W of multimode output power. For single-mode TEM₀₀ operation, an intracavity telescope was adopted for mode matching in the horizontal direction. Because of the folded cavity and the intracavity telescope, this laser head was the most compact to our knowledge of the TEM₀₀ grazing-incidence laser geometry. At last, an output power of 15 W was produced at 36 W of effective diode pump power. The stable Q-switching operation was also obtained. PACS 42.55.-f; 42.55.Xi; 42.60.Gd     

Neodymium concentration dependence of 0.94-, 1.06- and 1.34-μm laser emission and of heating effects under 809- and 885-nm diode laser pumping of Nd:YAG

Laser emission in the 0.94-, 1.06- and 1.34-micron ranges in diluted and concentrated Nd:YAG crystals longitudinally pumped by a 885-nm diode laser on the ⁴ I _9/2→⁴ F _3/2 transition is investigated. Continuous-wave operation at watt level in all these wavelength ranges is demonstrated with a 1.0-at. % Nd:YAG crystal; however, the laser performance is impeded by the low pump absorption efficiency. Improved output power and overall efficiency were obtained with a highly doped 2.5-at. % Nd:YAG crystal: 5.5 W at 1.06 μm and 3.8 W at 1.34 μm with 0.38 and 0.26 efficiencies, respectively. Comparative results with traditional pumping at 809 nm into the highly absorbing ⁴ F _5/2 level are presented, showing the advantage of the direct ⁴ F _3/2 pumping. The influence of the lasing wavelength and of the Nd concentration on the thermal effects induced by the optical pumping in the laser material is discussed. A clear relation between the heat generated in the Nd:YAG crystals in lasing and non-lasing regimes, a function of the Nd doping, is demonstrated. PACS 42.55.Rz; 42.60.By; 42.60.Da     

High power and highly efficient Nd:YAG laser emitting at 1123 nm

A diode-end-pumped continuous-wave (CW) Nd:YAG laser emitting at 1123 nm is realized efficiently in a 25-mm-long cavity. A composite Nd:YAG (cNd:YAG) crystal is selected as the gain medium. With an incident diode power of 26.1 W, an output power of up to 9.3 W is obtained, corresponding to an optical-to-optical conversion efficiency of 35.6%. The laser performances at 1123 nm are compared between composite Nd:YAG and common Nd:YAG crystals. The results show that composite Nd:YAG is a better choice for 1123-nm laser generations.     

A linearly polarized continuous-wave 1357-nm Nd:YAG laser

We demonstrated a linearly polarized continuous-wave Nd:YAG laser operating at a 1357-nm single-wavelength, by a 808-nm diode as an end-pump source. We chose a Brewster-angle-cut Nd:YAG laser host crystal, due to its two salient features as follow: linearly polarized laser output and single-wavelength oscillation can be easily obtained. In this paper, a continuous-wave all-solid-state single-wavelength laser operating at 1357 nm is demonstrated with a diode-end-pumped Brewster-cut Nd:YAG laser. The laser had a 1.03-W maximum output power under an incident pump power of 15.0 W, a 12.7% slope efficiency, a 6.9% optical-to-optical conversion efficiency, a 0.14-nm spectral linewidth and a 3% power-output stability within 30 min. PACS 42.55.Rz; 42.55.Xi; 42.70.Hj     

High power Nd:YAG slab laser sidepumped by diode laser array

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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).     

Intracavity optical parametric oscillator pumped by an actively Q-switched Nd:YAG laser

A non-critically phase-matched KTiOPO₄ optical parametric oscillator (OPO) intracavity pumped by a laser diode end-pumped acousto-optically Q-switchedNd:YAG laser is experimentally demonstrated. The highest average power is obtained at the pulse repetition rate (PRR) of around 15 kHz, which is different from the widely reported Nd:YVO₄ laser pumped OPO in which the highest average power is obtained at a very high PRR, e.g. 80 kHz. With an incident laser diode power of 6.93 W and a pulse repetition rate of 15 kHz, an average signal power of 0.72 W is obtained with a peak power of 7.7 kW and an optical-to-optical conversion efficiency of 10.4%. PACS 42.65.Yj; 42.60.Gd; 42.55.Xi     

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.     

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.     

CRRFA-30L波段射频加速器

主要介绍CRRFA-30L波段射频加速器结构和性能，论述了热阴极射频腔注入器、束流加速系统、微波功率源和控制等结构中主要技术及其研究进展，给出了加速器输出束流参数测量与测量结果分析，达到设计应用要求。     

Highly stable and efficient KTP-based intracavity optical parametric oscillator with a diode-pumped passively Q-switched laser

We present in this paper a highly stable and efficient KTP-based intracavity optical parametric oscillator with a diode-end-pumped Nd:YVO₄/Cr:YAG passively Q-switched laser. At the incident diode pump power of 4 W, the signal (1.57 μm) and idler (3.29 μm) average output powers up to 580 and 100 mW, respectively, have been achieved. The corresponding conversion efficiency from the input diode pump power to the output signal power is 14.5%, while that to the total OPO output (signal+idler) reaches 17%. To the best of our knowledge, these are the highest conversion efficiencies reported to date. After more than four hours of investigation, the OPO power stability better than 2% has been obtained. In addition, efficient cavity dumping of the IOPO has inevitably led to the short pulse duration (1.6 ns) and high peak power output (8.3 kW) at the signal wave. Additionally, the amplitude and repetition rate fluctuations of the signal pulses are well within 5%. PACS 42.55.Xi; 42.60.Gd; 42.60.Lh; 42.65.Yj     

Efficient sub-nanosecond intracavity optical parametric oscillator pumped with a passively Q-switched Nd:GdVO<Subscript>4</Subscript> laser

An efficient diode-pumped passively Q-switched Nd:GdVO₄/Cr⁴⁺:YAG laser was employed to generate a high-repetition-rate, high-peak-power eye-safe laser beam with an intracavity optical parametric oscillator (OPO) based on a KTP crystal. The conversion efficiency for the average power is 8.3% from pump diode input to OPO signal output and the slope efficiency is up to 10%. At an incident pump power of 14.5 W, the compact intracavity OPO cavity, operating at 46 kHz, produces average powers at 1571 nm up to 1.2 W with a pulse width as short as 700 ps. PACS 42.60.Gd; 42.65.Yj; 42.55.X     

Continuous-wave, 15.2 W diode-end-pumped Nd:YAG laser operating at 946 nm

A high-power continuous-wave (cw) Nd:YAG laser operating at 946 nm by utilizing a quasi-three-level transition is reported. The laser consists of a composite Nd:YAG rod end pumped by a fiber-coupled diode laser and a simple plane-concave cavity. At an incident pump power of 40.2 W, a maximum cw output of 15.2 W at 946 nm is obtained, achieving a slope efficiency of 45%. To the best of our knowledge, this is the highest output at 946 nm ever generated by diode-pumped Nd:YAG lasers. In addition, at an incident pump power of 15.2 W, a 1.25 W blue output at 473 nm is achieved with a simple compact three-element cavity and a type-I lithium triborate (LiB(3)O(5)) crystal as a frequency doubler.     

All-solid-state continuous-wave frequency doubling Nd:YAG/LBO laser with 8.2 W output power at 660 nm

An efficient and compact red laser at 660 nm is generated by intracavity frequency doubling of continuous wave (CW) laser operation of a diode pumped Nd:YAG laser at 1319 nm under the condition of suppression the higher gain transition near 1064 and 1319 nm under the condition of suppression the higher gain transition near 1064 and 1338 nm. With 40 W diode pump power and a frequency doubling crystal LBO, as high as 8.6 W of CW output power at 660 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.5% and the output power stability in 8 h is better than 2.73%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 660 nm generated by intracavity frequency doubling of a diode end pumped Nd:YAG laser at 1319 nm.     

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.     

Diode end-pumped high-power Q-switched double Nd:YAG slab laser and its efficient near-field second-harmonic generation

We reported on an all-solid-state double Nd:YAG slab laser. The laser was based on two diode end-pumped Nd:YAG slabs and a stable-unstable hybrid resonator. A cw output of 189 W and an average Q-switched output of 169 W at 10 kHz with an M(2) factor of 1.5 in the slow direction and 1.7 in the fast direction were obtained. We demonstrated efficient near-field frequency doubling by imaging the one-dimensional top-hat near-field to a lithium triborate frequency doubler. We obtained 93 W green light at 10 kHz with a pulse width of 10.7 ns. The efficiency of second-harmonic generation was up to 57%.