110 W ceramic Nd<Superscript>3+</Superscript> : Y<Subscript>3</Subscript>Al<Subscript>5</Subscript>O<Subscript>12</Subscript> laser

A high-power, continuous-wave 0.6% Nd³⁺-doped ceramic Y₃Al₅O₁₂ (Nd:YAG) laser has been developed. 110 W laser output at 1064 nm was obtained, with a slope efficiency of about 41%. The M² factor was found to be around 6. The laser performance of the ceramic laser material was found to compare favorably with that obtained with single crystal Nd:YAG. PACS 42.55.-f; 42.55.Xi; 42.70.Hj     

LD抽运Yb:GSO实现1090 nm低阈值激光运转

用Yb:Gd₂SiO₅(Yb:GSO)晶体实现激光运转.利用940 nm的二极管激光器作为抽运源，得到Yb:GSO激光器的激光中心波长为1090 nm，抽运阈值功率密度仅为1.27 kW/cm²，小于Yb:YAG的理论阈值1.53 kW/cm².利用2%的输出镜得到最大输出功率为360 mW，相应的斜效率为19%. 关键词： Yb:GSO晶体 激光二极管抽运 阈值     

Continuous-wave high-power Nd:YAG-KNbO3 laser at 473 nm

A continuous-wave high-power Nd:YAG laser operating on the ⁴F_3/2→⁴I_9/2 transition at 946 nm and intracavity frequency-doubled to 473 nm by a KNbO₃ nonlinear crystal at room temperature is reported. The Nd:YAG laser outputs a randomly polarized beam of 3.8 W maximum power (38% optical-to-optical efficiency and 44% slope efficiency with respect to the absorbed pump power) at the 946 nm fundamental wavelength. Intracavity frequency-doubling with a 2.0-mm thick KNbO₃ crystal in a linear resonator yielded 159-mW single-ended blue-output with 4.8% optical-to-optical conversion efficiency versus the absorbed pump power. The 473-nm maximum power of 418 mW with 11.6% optical-to-optical conversion efficiency in absorbed power was obtained from a V-type resonator; the overall optical-to-optical conversion efficiency was 6.7%, while the conversion of the available infrared power reached 50%.     

Resonantly-pumped Er3+:Y2O3 ceramic laser for remote CO2 monitoring

Laser performance of resonantly-pumped Er³⁺-doped Y₂O₃ ceramic laser for remote DIAL CO₂ monitoring is reported. Slope efficiency of 64.6% and output power of over 9.3 W have been achieved with this eyesafe, 1.6-μm, CW laser in a cryogenically cooled operation regime despite the marginal optical quality of currently available laser gain material.     

Diode-laser-array end-pumped 14.3-W CW Nd:GdVO4 solid-state laser at 1.06 μm

A diode-laser-array end-pumped efficient CW Nd:GdVO₄ laser at 1.06 μm has been developed. A low-order-mode output power of 14.3 W was obtained at the maximum available pump power of 26 W, giving an optical conversion efficiency of 55% and an average slope efficiency of 62%. The laser output beam quality factor at full pump power was determined to be M²<1.8. It is also shown that only lightly doped Nd:GdVO₄ crystals are suitable for high-power end-pumped lasers. Received: 4 May 1999 / Published online: 29 July 1999     

LD-pumped passively Q-switched Nd:YVO4/YVO4 laser with an Nd3+:Cr4+:YAG saturable absorber

By using a piece of codoped Nd³⁺:Cr⁴⁺:YAG crystal as a saturable absorber, a laser-diode pumped passively Q-switched Nd:YVO₄/YVO₄ laser has been realized. The maximum laser output power of 2.452 W has been obtained at the incident pump power of 8.9 W for an 8.8% transmission of the output coupler at 1064 nm, corresponding to a slope efficiency of 30%. The other output laser characteristics of the laser have also been investigated. The laser with a Nd³⁺:Cr⁴⁺:YAG saturable absorber has a lower threshold pump power and a higher slope efficiency compared to that with a similar small-signal transmission of a Cr⁴⁺:YAG saturable absorber.     

Laser operation of the new stoichiometric crystal KYb(WO4)2

We demonstrate for the first time laser operation with the monoclinic stoichiometric crystal KYb(WO₄)₂ (hereafter KYbW). Lasing on the ² F _5/2 ?² F _7/2 transition of Yb³⁺ at room temperature has been achieved near 1074 nm with >41% slope efficiency (>26% maximum conversion efficiency) using a 0.5-mm-thick plate of KYbW. This new laser material holds great promise for diode-pumped high-power lasers, thin-disk and waveguide designs as well as for ultrashort (ps/fs) pulse laser systems. Received: 10 October 2001 / Revised version: 19 November 2001 / Published online: 17 January 2002     

Efficient tunable laser operation of diode- pumped Yb,Tm:KY(WO4)2 around 1.9 μm

A new laser medium – Yb,Tm:KY(WO₄)₂ – for diode pumped solid state laser applications operating around 1.9 to 2.0 μm has been investigated and the main laser characteristics are presented. Diode pumping at 981 nm and around 805 nm was realised. For 981-nm pumping, the excitation occurs into Yb³⁺ ions followed by an energy transfer to Tm³⁺ions. A slope efficiency of 19% was realised. For pumping around 805 nm, the excitation occurs directly into the Tm³⁺ ions. Here a maximum slope efficiency of 52%, an optical efficiency of 40%, and output powers of more than 1 W were realised. Using a birefringent quartz plate as an intracavity tuning element, the tunability of the Yb,Tm:KY(WO₄)₂ laser in the spectral range of 1.85–2.0 μm has been demonstrated. The possibility of laser operation in a microchip cavity configuration for this material has also been shown. Received: 12 March 2002 / Revised version: 20 May 2002 / Published online: 25 September 2002 RID="*" ID="*"Corresponding author. Fax: +49-531/592-4116, E-mail: stefan.kueck@ptb.de     

Dual-Wavelength and Passively Q-Switched Nd :GdVO4 Lasers Operated at 1.34 μm Under 880 nm Diode Pumping

We report continuous-wave (CW) and passively Q-switched Nd :GdVO₄ lasers on ⁴F_3/2 → ⁴I_13/2 transition directly pumped by an 880 nm diode laser. A widely investigated Nd :GdVO₄ laser at about 1341 nm is operated with a maximum output power of 5.23 W and a slope efficiency of about 30.6%. Using an etalon for wavelength selection, we realize laser emission at about 1344 nm, for the first time to our knowledge, in a Nd :GdVO₄ laser, with a maximum output power of 4.19 W and a slope efficiency of 20.1%. Moreover, we achieve simultaneous dual-wavelength lasing at 1341 and 1344 nm with a maximum output power of 2.27 W and a slope efficiency of 13.5%, respectively. Using V³⁺ :YAG as a saturable absorber, stable Q switching is obtained at about 1341 nm with a maximum average output power of 1.15 W. The pulse width is 52.8 ns at a repetition rate of 279.8 kHz.

     

Diode pumped Nd:GSAG and Nd:YGG laser at 942 and 935 nm

Two new Nd³⁺ doped crystals show laser activity between the ⁴F_3/2 and ⁴I_9/2 levels. Diode pumped emission of Nd:GSAG at 942 nm wavelength with 950 mW output power and 14% optical to optical efficiency as well as laser emission of Nd:YGG at 935 nm with 700 mW output power and 11% efficiency have been obtained. These wavelengths are useful for water vapour absorption measurements.     

Stimulated emission and laser action of Pr3+-doped YA1O3

Groundstate absorption, fluorescence, excited-state absorption, and stimulated emission of Pr:YA1O₃ were measured in dependence on the polarization. The results reflect the anisotropy of the host lattice. Especially the polarized spectra of the stimulated emission fit very well with the laser data of this material. Seven cw laser transitions in the visible spectral range obtained so far in Pr:YA1O₃ with argon-ion laser pumping were identified in the spectra of the stimulated emission. In addition, two infrared cw laser transitions were realized. The best results were achieved for the³ P ₀³ F ₄ laser transition at 746.9 nm with a maximum slope efficiency of 24.6%, a maximum output power of 49.6 mW, and a laser threshold of 25 mW.     

High-power diode-pumped Tm:YLF laser

A high-power, continuous-wave 3.5% Tm³⁺ doped LiYF₄ (Tm:YLF) laser has been developed. Using two Tm:YLF rods in a single cavity, 55 W of laser output at 1910 nm was obtained with a slope efficiency of 49%. The M² factor was found to be <3. With a single Tm:YLF rod, a maximum laser power of 30 W was obtained with a slope efficiency of 50%. The laser was tuned to the peak absorption wavelength of Ho:YAG of 1907.5 nm by an intracavity quartz etalon with an output power loss < 1 W. PACS 42.55.-f; 42.55.Xi; 42.60.Pk     

High repetition rate LiF<Stack><Subscript>2</Subscript><Superscript>−</Superscript></Stack>: Color center laser

The efficient oscillation of LiF:F₂⁻ color center laser pumped by a compact LD-pumped Nd:YVO₄ acousto optically Q-switched laser with 30 kHz pulse repetition rate was demonstrated. The broadband oscillation with 75 μJ pulse energy and 37 kW peak power with the slope efficiency 20% was obtained. The average output power as high as 230 mW was reached. The narrow line tunable from 1.10 to 1.29 μm laser radiation with 10% conversion efficiency in the maximum of the tuning curve was achieved under pumping with 1.6 W average pump power.     

Diode-pumped continuous-wave Nd:YLF laser at 1313 nm

We present an efficiency Nd:LiYF₄ (Nd:YLF) laser operating at 1313 nm pumped directly into the emitting level ⁴ F _3/2. At the incident pump power of 10.3 W, as high as 3.1 W of continuous-wave output power at 1313 nm is achieved. The slope efficiency with respect to the incident pump power was 36.1%. To the best of our knowledge, this is the first demonstration of such a laser system. Comparative results obtained for the pump with diode laser at 806 nm, into the highly absorbing ⁴ F _5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.     

Highly efficient continuous-wave intracavity frequency-doubled Nd:YVO4-LBO laser at 457 nm under diode pumping into the emitting level 4F3/2

The continuous-wave high efficiency laser emission of Nd:YVO₄ at the fundamental wavelength of 914 nm and its 457 nm second harmonic obtained by intracavity frequency doubling with an LBO nonlinear crystal is investigated under pumping by diode laser at 880 nm into emitting level ⁴F_3/2. 6.5 W at 457 nm with M ²=1.8 was obtained from a 5-mm-thick 0.4 at.% Nd:YVO₄ laser medium and a 15-mm-long LBO nonlinear crystal in a Z-type cavity for 18.6 W absorbed pump power. An optical-to-optical efficiency with respect to the absorbed pump power was 0.35. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing level ⁴F_5/2, are given in order to prove the advantages of the 880 nm wavelength pumping.     

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     

Performance study of the KrCl discharge laser with liquid chlorine donors

The effects of liquid chlorine donors (BCl₃ and CCl₄) on the output energy and the efficiency of a KrCl laser (222 nm) are investigated. Maximum laser energies of 230 mJ (3.3 J/l) in pulses of 16 ns duration were obtained from a 0.035% BCl₃/10.1% Kr/89.8% Ne mixture at a total pressure of 2600 Torr, and at a specific power loading of about 24 MW/cm³, a power conversion efficiency of 0.86% was obtained. These figures are reduced by a factor of two when He is used as buffer gas. Much weaker laser emissions were obtained when CCl₄ was used as a chlorine donor.     

500 W Nd:YAG zigzag slab MOPA laser

A MOPA Nd:YAG laser with end-pumped zigzag slab architecture has been developed. 277 W laser output is obtained from the master-oscillator stage, corresponding to the average slope efficiency of 35.9% and the optical conversion efficiency of 34.6%, which emits the maximum power of 402 with 1163 W of pump power. Furthermore, the amplifier stage produces 505 W with the slope efficiency of 24% and the extraction efficiency of 25%. The beam quality is estimated as M _x ² ≈ 10, M _y ² ≈ 50 in the orthogonal directions respectively.     

Diode-pumped monolithic Er3+:Yb3+:YAl3(BO3)4 micro-laser at 1.6 μm

Efficient eye-safe 1.6 μm monolithic laser was realized in a c-cut, 0.7-mm-thick Er³⁺:Yb³⁺:YAl₃(BO₃)₄ microchip end-pumped by a quasi-continuous-wave 970 nm diode laser. At incident pump peak power of 20.4 W, a maximum output peak power of 2.6 W with a slope efficiency of 19% was obtained when the waist radius of pump laser beam was 220 μm. The spectra and profiles of output beam of the Er³⁺:Yb³⁺:YAl₃(BO₃)₄ monolithic laser were measured. The influences of the waist radius of pump laser beam on the slope efficiency and threshold of the monolithic laser were also investigated.     

Diode-pumped orthogonally polarized dual-wavelength Nd3+:LaBO2MoO4 laser

Polarized spectroscopic properties related to 1.07 μm laser operation of a 1.8 at.% Nd³⁺:LaBO₂MoO₄ crystal grown by the Czochralski method were investigated at room temperature. Using a 2.2-mm-thick, Z-cut Nd³⁺:LaBO₂MoO₄ crystal as gain medium, orthogonally polarized dual-wavelength laser at 1,068 and 1,074 nm was first realized in a plano-concave resonator end-pumped by a quasi-continuous-wave 795 nm diode laser. A total output peak power of 1.2 W with slope efficiency of 26 % around 1.07 μm was obtained. The influences of resonator length and pump power on output laser wavelength were also investigated.