Nd:YAG陶瓷与单晶4F3/2–4I13/2跃迁的弱谱线多波长激光性能对比

报道了基于半导体激光端面抽运Nd:YAG的⁴F_3/2–⁴I_13/2 跃迁的弱谱线多波长激光输出. 实验对比了透明陶瓷与单晶材料的激光输出特性, 表明透明陶瓷和单晶材料荧光谱强度的略微差异, 导致了多波长输出时相同两个波长之间的激光强度比在两种材料中的差异. 基于两种耦合输出镜片, 激光阈值都在2 W左右. 在13.5 W的抽运功率下, 基于Nd:YAG透明陶瓷获得了输出功率4.05 W、强度比1 :2的1338与1356 nm双波长激光和输出功率3.65 W、强度比13 : 1的1356与1414 nm 双波长激光, 斜率效率分别达33.9% 和31.9%.     

Performance of a low-loss pulsed-laser-deposited Nd:Gd(3) Ga(5)O(12) waveguide laser at 1.06 and 0.94 mum

We report the laser performance of a low-propagation-loss neodymium-doped Gd(3)Ga(5)O(12) (Nd:GGG) waveguide fabricated by pulsed-laser deposition. An 8- mum -thick crystalline Nd:GGG film grown upon an undoped Y(3)Al(5)O(12) substrate lases at 1.060 and 1.062 microm when pumped by a Ti:sapphire laser operating at 740 or 808nm.Using a 2.2% output coupler, we observed a 1060-nm laser threshold of 4mW and a slope efficiency of 20%. Laser action was also achieved, for what we believe is the first time in Nd:GGG, on the quasi-three-level 937-nm transition. With a 2% output coupler at this wavelength a laser threshold of 17mW and a 20% slope efficiency were obtained. This demonstration of low propagation loss combined with the fact that these waveguides have a very high numerical aperture (0.75) makes pulsed-laser-deposited thin films attractive for high-power diode-pumped devices.     

Q-switched neodymium-doped Y3Al5O12-based silica fiber laser

We present pulsed laser operation in a Nd-doped, Y3Al5O12-based silica fiber. The fiber was fabricated using the rod-in-tube technique with a Nd:YAG crystal rod as the core material and a silica tube for the cladding material. A spectroscopy study revealed that the core region had become amorphous in the process of fiber drawing. Q-switched pulsed laser operation was realized at a wavelength of 1058 nm when the fiber was cladding pumped at a wavelength of 808 nm. The laser delivered 38 μJ of energy in 65 ns pulses. The extracted energy was limited due to the multimodal operation of the fiber. Laser slope efficiency in continuous wave operation reached 52%. The spectroscopic properties of the fabricated fiber are discussed and compared to a Nd:YAG crystal and a Nd:Al-doped silica fiber.     

1 J/pulse Q-switched 2 microm solid-state laser

Q-switched output of 1.1 J/pulse at a 2.053 microm wavelength has been achieved in a diode-pumped Ho: Tm: LuLF laser with a side-pumped rod configuration in a master-oscillator-power-amplifier (MOPA) architecture. This is the first time to our knowledge that a 2 microm laser has broken the joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single- and double-pulse operation, respectively. The system produces an excellent 1.4 times transform-limited beam quality.     

Nd^3＋：La2Be2O5单晶的光谱特性

Ｎｄ（３＋）：Ｌａ２Ｂｅ２Ｏ５（Ｎｄ（３＋）：ＢＥＬ）是一种具有单斜结构的双轴晶体，发射线性偏振荧光谱，当Ｅ∥Ｘ时，荧光峰值波长为１．０７０μｍ，Ｅ∥ｙ（ｂ）时，＝１．０７９μｍ．本文测量了Ｎｄ（３＋）：ＢＥＬ单晶的吸收谱，偏振和非偏振荧光谱，低温荧光谱（７７Ｋ°）和荧光寿命，（τ＝１３５±５μｓ），并且分析了其光谱特性与Ｎｄ（３＋）：ＹＡＧ作了比较，认为Ｎｄ（３＋）：ＢＥＬ更适合激光二极管泵浦．     

Efficient approximately 2 microm Tm3+ -doped tellurite fiber laser

Laser emission in the range of 1.88-1.99 micrim from a Tm3+ -doped tellurite fiber is demonstrated when pumped with a diode-pumped Er3+/Yb3+-doped silica fiber laser operating at 1.57-1.61 microm. This pump source excites the Tm3+ ions directly into the F43 upper laser level and yields an output power of 280 mW with a slope efficiency of 76% in a 99%-12% laser cavity arrangement and a 32 cm long fiber. This result is very close to the Stokes efficiency limit of approximately 80%. This is, to the authors' knowledge, the first demonstration of high efficiency lasing in a tellurite fiber at wavelengths longer than 1.56 microm.     

High-power diode-pumped continuous-wave Nd(3+) lasers at wavelengths near 1.44 microm

We demonstrate longitudinally diode-pumped operation of Nd:YAG and Nd:YAP lasers at the long-wavelength end of the (4)F(3/2) ? (4)I(13/2) transition in the eye-safe spectral region at 1444 and 1430 nm, respectively. Special crystal coatings were required for achievement of lasing at these wavelengths. Output powers of up to 4.9 and 2.2 W, with slope efficiencies of up to 22% and 8%, respectively, were achieved. Polarized operation of the Nd:YAG laser yielded output powers of 76% as compared with unpolarized operation. Because of thermal stress, both YAG and YAP crystals were fractured at roughly 25 W of absorbed longitudinal pump power.     

High-peak-power operation of a Q-switched Tm3+-doped silica fiber laser operating near 2 microm

A peak output power of greater than 4.1 kW and a pulse duration at FWHM of 150 ns have been obtained in a Q-switched Tm3+-doped silica fiber laser in the wavelength region near 2 microm when the laser was pumped with a Nd:YAG laser operating at 1.319 microm. An acousto-optic modulator was used as a Q-switching element and operated at repetition rates of as much as 30 kHz. A core diameter of 17 microm was used to increase the laser gain volume, permitting high-pump-power absorption and an output of high pulse energy and peak power. Stimulated Brillouin scattering was directly observed in the output pulse, and as much as 10 orders of stimulated Brillouin scattering was recorded. This is the first report to the authors' knowledge of high-peak-power operation of a Tm3+-fiber laser.     

High-peak power,passively Q-switched,composite, all-poly-crystalline ceramics Nd:YAG/Cr<Superscript>4+</Superscript>:YAG laser and generation of 532-nm green light

Output performances of passively Q-switched, composite Nd:YAG/Cr⁴⁺:YAG lasers that consisted of bonded, all-poly-crystalline ceramics Nd:YAG and Cr⁴⁺:YAG are reported. Laser pulses at 1.06 μm with 2.5-mJ energy and 1.9-MW peak power are obtained from a 1.1-at % Nd:YAG/Cr⁴⁺:YAG ceramics that was quasi-continuous-wave (quasi-CW) pumped with a diode laser. Single-pass frequency doubling with LiB₃O₅ (LBO) nonlinear crystal at room temperature yielded green laser pulses at 532 nm of 0.36-mJ energy and 0.3-MW peak power, with a conversion efficiency of 0.27.     

Efficient room-temperature operation of Cr3+-sensitized,flashlamp-pumped, 2µm lasers

Utilizing the results of Cr³⁺ → Tm³⁺ transfer efficiency studies, we have demonstrated that yttrium aluminium garnet (YAG) is the preferred host for room-temperature, flashlamp-pumped solid-state lasers operating in the 2.0 µm spectral range. We report data on two different sensitizer-activator combinations in YAG and yttrium scandium gallium garnet (YSGG) laser materials: one is doped with Cr:Tm:Ho and operates on the Ho³⁺⁵I₇ →⁵I₈ transition at 2.097 µm; the other is doped only with Cr:Tm, which lases on the Tm³⁺³F₄ →³H₆ transition at 2.014 µm. We have achieved a slope efficiency of 5.1% with the Cr:Tm:Ho:YAG laser, which is the highest slope efficiency yet reported for a room-temperature, flashlamp-pumped, 2 µm solid-state laser. We have measured thresholds as low as 38 J and output energies >1.5 J for that system. We also report the first room-temperature operation of an efficient flashlamp-pumped Cr:Tm:YAG laser at 2.014 µm. Thresholds as low as 43 J, output energies exceeding 2 J, and slope efficiencies as high as 4.5% have been achieved. This is an order of magnitude higher than the efficiency previously reported for a 2.01 µm Cr:Tm:YAG laser operated at cryogenic temperatures. These two efficient 2 µm laser systems (Cr:Tm:Ho:YAG and Cr:Tm:YAG) are discussed in terms of their potential for Q-switched operation.     

Longitudinally diode-pumped Nd:YAG double-clad planar waveguide laser

We report the demonstration of a near-diffraction-limited, compact, diode-end-pumped double-clad planar waveguide Nd:YAG laser. Efficient laser operation was achieved for the three dominant Nd(3+) transitions, at 1.064, 0.946, and 1.32microm , with TE polarized output powers of 1.33, 0.57, and 0.33 W for the available output couplers. The output beam from the monolithic plane-plane laser cavity had measured M(2) values of 1.0 and 1.8 perpendicular and parallel, respectively, to the plane of the waveguide.     

Generation of vacuum-ultraviolet light by an optically contacted,prism-coupled KBe2BO3F2 crystal

We have demonstrated the second harmonic of a frequency-tripled Nd:YVO4 laser with 2.5-mW quasi-cw output by using an optically contacted, prism-coupled KBe2BO3F2 crystal. We also achieved the second harmonic with a frequency-doubled single-mode Ti:sapphire laser at 172.5 nm and sum-frequency mixing with a dual-wavelength Ti:sapphire laser at 163.3 nm. These wavelengths are to our knowledge the shortest obtained by use of nonlinear crystals for second-harmonic generation and sum-frequency mixing, respectively.     

用1064nm激光增强HfO2/SiO2薄膜的抗激光损伤能力的实验研究

 用1 064nm激光实验研究了HfO₂/SiO₂薄膜的激光损伤增强效应，实验以薄膜激光损伤阈值70%的激光能量开始，采用N-ON-1方式处理薄膜，激光脉冲的能量增量为5J/cm²。实验结果表明，激光处理薄膜表面能使激光损伤阈值平均提高到3倍左右，并且薄膜的损伤尺度也明显减小。对有缺陷的薄膜，其缺陷经低能量激光后熔和消除，其抗激光损伤能力得到增强，但增强得并不显著，而薄膜本身的激光预处理，可以使其激光损伤阈值大大提高。     

Incommensurate magnetic ordering in Cu2Te2O5X2 (X = Cl,Br) studied by neutron diffraction

We present the results of the first neutron powder and single crystal diffraction studies of the coupled spin tetrahedra systems Cu2Te2O5X2 (X = Cl,Br). Incommensurate antiferromagnetic order with the propagation vectors kCl approximately [0.150,0.422,1/2], kBr approximately [0.158,0.354,1/2] sets in below TN = 18 K for X = Cl and 11 K for X = Br. No simple collinear antiferromagnetic or ferromagnetic spin arrangements within Cu2+ tetrahedra fit these observations. Fitting the diffraction data to more complex but physically reasonable models with multiple helices leads to a moment of 0.67(1)microB/Cu2+ at 1.5 K for the Cl compound. The reason for such a complex ground state may be geometrical frustration of the spins due to the intratetrahedral and intertetrahedral couplings having similar strengths. In neither compound has any evidence for a structural transition accompanying the magnetic ordering been found.     

Efficient, multiwatt, continuous-wave laser operation on the (4)F((3/2))-(4)I((9/2)) transitions of Nd:YVO(4) and Nd:YAG

We report multiwatt, diode-pumped cw operation on the (4)F(3/2)-(4)I(9/2) laser transition at 914.5 nm in Nd:YVO(4), for which an output power of 3.0 W and a slope of efficiency of 22.8% were achieved. For the corresponding laser transition of Nd:YAG at 946 nm an output power of 5.35 W and a slope efficiency of 40.2% were measured. By intracavity frequency doubling, an output power of 1.5 W at 473 nm was generated.     

Gd3+/Y3+共掺对Nd:CaF2晶体光谱性能的影响

通过坩埚下降法生长了系列共掺Nd,Gd:CaF₂和Nd,Y:CaF₂晶体, 研究了Gd³⁺/Y³⁺共掺对Nd³⁺光谱性能以及Nd:CaF₂晶体晶胞参数的影响规律. 对于0.5 at.%Nd, x at.%Gd(x=2,5,8,10):CaF₂系列晶体, 当调控Gd³⁺掺杂浓度为2 at.%时, 具有最大的荧光寿命499 μs; 当Gd³⁺掺杂浓度为5 at.%时, 具有最大的吸收截面1.47×10^-20 cm², 最大的发射截面1.9×10^-20 cm²; 当Gd³⁺掺杂浓度为8 at.%时, 具有最佳的发射带宽29.03 nm. 对于0.6 at.%Nd, xat.%Y(x=2, 5, 8, 10):CaF₂系列晶体, Y³⁺掺杂浓度为5 at.%时, 有最大的吸收截面2.41×10^-20 cm², 最大的发射截面3.17×10^-20 cm²; 当Y³⁺掺杂浓度为10 at.%时, 具有最长的荧光寿命359.4 μs,并且具有最大发射带宽26 nm.     

Cs(6 ~2D_(5/2))与H_2反应生成的CsH分子的转动和振动态分布

利用激光泵浦-探测技术,在样品池条件下,研究了Cs(6D5/2)态与H2反应生成的CsH分子基电子态的转动和振动的量子态分布。在Cs-H2混合蒸气中,脉冲激光双光子激发Cs(6D5/2)态,另一台调频脉冲激光器扫描CsHX1Σ+(v″,J″)→A1Σ+(v′,J′=J″±1)吸收线,发现CsH分子只有v″=0和1上的振动带上有布居而不布居在v″1的振动带上。v″=0和1上的转动带分布呈现单峰结构,其峰值位于J″=6～8处,转动带分布轮廓与池温下的统计分布接近。转动Boltzmann温度分别为(458±20)K(对v″=1)和(447±18)K(对v″=0),得到的CsH分子的转动温度稍低于池温。从转动态分布得到v″=1与v″=0上布居数之比约为0.897,从而计算出CsH基电子态上的平均转动能ER和平均振动能EV,有效能减去平均振转能得到平均平动能ET。CsH分子3种能量的相对比值fT∶fV∶     

Automatic continuous scanning and random-access switching of mid-infrared waves generated by difference-frequency mixing

We report the rapid tuning of mid-infrared waves beyond 5 microm emitted in difference-frequency mixing with an electronically tuned dual-wavelength Ti:Al2O3 laser used as a pumping source. Simultaneous rapid tuning of the dual wavelengths, which satisfy phase matching in AgGaS2, allows rapid random access switching and continuous tuning of mid-infrared wavelengths. In random-access switching, the mid-infrared wavelength is tuned every pulse shot at a repetition rate of 1 kHz. Mid-infrared wavelengths continuously tuned from 5.2 to 7.2 microm, from 7.0 to 9.1 microm, and from 8.9 to 12.0 microm are achieved at phase-matched angles of 55 degrees, 50 degrees, and 45 degrees, respectively.     

Laser and self-Raman-laser oscillations of PBMoO4:Nd3+ crystal under laser diode pumping

Different regimes of laser operation and stimulated Raman scattering (SRS) for a laser diode (LD)-pumped PbMoO4:Nd3+ crystal have been investigated. Under 1.5 W LD pumping, the output power of the PbMoO4:Nd3+ laser in the free-running mode at 1056 nm reached 0.65 W with a slope efficiency of up to 53%. Using different LiF: F-2 saturable absorbers, we achieved a maximum pulse energy of 11 microJ at a 1.4 ns pulse duration and a maximum output power of 0.35 W (10 microJ) at a 7 ns pulse width in the passively Q-switched mode. PbMoO4:Nd3+ self-Raman-laser operation at 1163 nm (first Stokes) was obtained for the first time, to our knowledge. The self-Raman-laser output pulse energy was measured to be as high as 6 microJ and the pulse duration was estimated to be shorter than 500 ps.     

Nd:YSAG单晶的光谱和激光性能

用提拉法生长了(1.5 at.%)Nd~(3+):Y_3Sc_2Al_3O_(12)(YSAG)激光晶体,摇摆曲线表明晶体结晶质量优良.测量了该晶体的吸收和发光光谱,表明其适合成熟的808 nm激光二极管(LD)抽运,其~4F_(3/2)→~4I_(11/2)跃迁最强发射波长为1059 nm,发射截面为1.03×10~(-19)cm~2,同时其激光上能级寿命为253μs,表明Nd:YSAG具有和Nd:YAG相近的效率,但其激光上能级寿命比Nd:YAG长约20μs.以LD抽运2 mm×2 mm×6 mm Nd:YSAG激光棒,激光阈值为0.85 W,最高输出功率为1.1 W,激光斜效率为21.1%,光-光转化效率为18.3%.综合表明Nd:YSAG单晶作为激光性能优良的全固态激光材料,更适合全固态调Q激光输出.