Nd：S—FAP晶体1.328μm激光特性研究

用染料激光和氙灯泵浦实现了ＮｄＳ－ＦＡＰ晶体低阈值、高效率的１．３２８μｍｍ激光运转。在透过率７％的平－平腔情况下，染料激光泵浦斜效率为３８％，阈值４．５ｍＪ，倍频红光波长为０．６６４μｍ，线宽１．３ｎｍ；采用氙灯泵浦（４×３０ｍｍ），实现了１．３２８μｍ自由运转，阈值为２４０ｍＪ，斜效率为０．８５％。测量了不同腔长，不同透过率情况的输出能量、光束发散角和偏振特性等。     

Spectroscopic characterization and laser performance of resonantly diode-pumped Er(3+)-doped disordered NaY(WO4)2

We report what is believed to be the first resonantly pumped laser operation based on Er(3+)-doped disordered double tungstate single crystal. Efficient laser operation of an Er(3+):NaY(WO(4))(2) laser at ～1609.6 nm was demonstrated with the naturally wideband, ～20 nm, InGaAsP/InP laser diode pumping at ～1501 nm. Laser wavelength tunability of ～34 nm was also demonstrated based on disorder-broadened emission features of Er(3+):NaY(WO(4))(2) single crystal.     

Frequency tuning and doubling in Yb-doped fiber lasers

A compact Yb-doped fiber laser (YDFL) based on a tunable fiber Bragg grating (FBG) with ～6 W output power and ～45 nm tuning around 1080 nm has been developed. The laser output power and its spectral width (～0.15 nm) do not change significantly at the tuning, while the FBG reflection coefficient increases with an increase in FBG compression. It has been shown that this increase is due to stress-induced changes in the FBG’s refractive-index modulation amplitude. Intracavity frequency doubling in the YDFL has also been performed. About 0.4 W of green radiation with tuning in the range 540–548 nm has been achieved with a KTP nonlinear crystal.     

半导体激光器抽运新型高效、调谐Yb∶LYSO激光器

报道了以掺Yb介质硅酸镥钇晶体为增益介质的激光行为。在自由运转的条件下,在1086 nm的中心波长处用2.5%的输出耦合镜得到7.8 W的连续激光输出,相应的斜效率为64%。利用SF14棱镜作为腔内调谐元件,激光输出的调谐范围为1014~1091 nm。     

Integrated optical Ti:Er:LiNbO3 distributed Bragg reflector laser with a fixed photorefractive grating

For the first time to the authors' knowledge, an integrated optical distributed Bragg reflector laser with a fixed photorefractive grating in LiNbO(3) is demonstrated. Sample preparation, grating fabrication, and laser characteristics are reported. The device is pumped by a fiber pigtailed laser diode (lambda(p) approximately 1480 nm) through the Bragg grating in a double-pass configuration, yielding an emission in the backward direction at lambda=1531.7nm . The laser threshold is 40 mW; as much as 5 mW of output power has been obtained at 110 mW of launched pump power in cw operation.     

Diode-pumped cw Nd:YAG three-level laser at 869 nm

We report for the first time (to our knowledge) a diode-pumped Nd:YAG laser emitting at 869 nm based on the (4)F(3/2)-(4)I(9/2) transition, generally used for a 946 nm emission. Power of 453 mW at 869 nm has been achieved in cw operation with a fiber-coupled laser diode emitting 35.4 W at 809 nm. Intracavity second-harmonic generation in the cw mode has also been demonstrated with power of 118 mW at 435 nm by using a BiB(3)O(6) nonlinear crystal. In our experiment, we used a LiNbO(3) crystal lens to complement the thermal lens of the laser rod, and we obtained good beam quality and high output power stability.     

Diode-end-pumped Tm:GdVO4 laser operating at 1818 and?1915?nm

High power operation at 1818 and 1915 nm has been demonstrated from a Tm:GdVO₄ laser operating in quasi-continuous-wave mode with a maximum measured power of 8.7 W and a laser output energy of 175 mJ was observed in a 20 ms pulse at 1.9 μm. The operation at 1818 nm is the shortest wavelength achieved at multi-watt power levels for a Tm-doped solid-state laser without intra-cavity tuning elements. It has been shown that by careful analysis of the emission spectra, the Tm:GdVO₄ laser can be tuned over a 100 nm wavelength range simply by appropriate selection of the reflectivity of the output coupler.     

Upconversion Spectrum of Tm-doped Fiber Pumped by Multiwavelengths from 760 nm to 810 nm

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Efficient diode-pumped intracavity frequency-doubled CW Nd : YLF laser emitting in the red

We demonstrate an efficient continuous-wave diode-pumped Nd : YLF laser emitting in the red (660.5 and 657 nm) by intracavity frequency doubling with a LBO crystal. We obtained more than 1 W of average power (in two output beams) for 12 W of pump power with a TEM₀₀ mode. This power is to our knowledge the highest obtained with a frequency-doubled Nd : YLF laser emitting in the red. Comparison between “a-cut” and “c-cut” crystals has been carried out in terms of performance and wavelength emission.     

Q-switched operation of an in-band-pumped Ho:LuAG laser with kilohertz pulse repetition frequency

We report continuous-wave (CW) and repetitively Q-switched operation of an in-band-pumped Ho:LuAG laser at room temperature. End-pumped by a Tm:YLF solid-state laser with emission wavelength of 1.91 μm, the CW Ho:LuAG laser generated 5.4-W output at 2100.7 nm with beam quality factor of M ²～1.03 for an incident pump power of 14.1 W, corresponding to slope efficiency of 67% with respect to absorbed pump power. Up to 1.5-mJ energy per pulse at pulse repetition frequency (PRF) of 3 kHz and 4.5-W average power with FWHM pulse width of 28 ns at 5 kHz were demonstrated in repetitively Q-switched operation.     

Continuous-wave intracavity frequency-doubled Nd:Yag-KTiOPO<Subscript>4</Subscript> red laser

Efficient and compact red laser output at 669 nm is generated by intracavity frequency doubling of a continuous-wave (CW) diode-pumped Nd:YAG laser at 1338 nm. With 16.9 W of diode pump power and the frequency-doubling crystal KTiOPO₄ (KTP), a maximum output power of 582 mW in the red spectral range at 669 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 3.4%; the output power stability over 4 h is better than 3.6%. To the best of our knowledge, this is first work on intracavity frequency doubling of a diode pumped Nd:YAG laser at 669 nm.     

激光二极管泵浦Nd:YAG 946nm激光器及倍频研究

提出如何克服准三能级再吸收损耗和抑制寄生振荡实现LD泵浦的Nd:YAG946nm激光器.在室温下946nm连续输出大于120mW,斜率效率接近10%,同时采用KNbO₃晶体实现了腔内倍频的蓝色激光输出.对实验结果进行了分析并提出了改进措施.     

Properties of (InGa)As/GaAs QW (λ ≈ 1.2 µm) facet-coated edge emitting diode laser

In this paper, we report on the design and optical properties of laser diodes with an emission wave-length of ～1170 nm based on an (InGa)As/GaAs double quantum well active layer. The back and front facet of the laser diodes were coated with SiO_x dielectric films that influence the output optical power by enhancing or lowering the facet reflectivity. The measurements show improvement of the facet-coated laser diode properties in the threshold-current-density reduction along with light output power enhancement. Furthermore, a narrow far field pattern and high side mode suppression have been observed.     

全固态Cr:LiSAF激光器的研究

本文报道了红光激光二极管泵浦的Cr:LiSAF激光器.采用纵向泵浦的平凹腔结构,在脉冲方式泵浦下,当泵浦平均功率为54mW,重复频率为200Hz时得到平均功率为5mW的激光输出,在连续波状态下,测得了输出功率随泵浦功率的变化曲线.激光输出的中心波长为873nm.     

Nd:GdVO4 as a three-level laser at 879 nm

We present what we believe to be the first true three-level laser based on a Nd-doped crystal. From the 4F3/24I9/2 laser transition, the lower laser level being the ground state, emission at 879 nm in NdGdVO4 has been obtained with diode pumping. Up to 0.8 W of power has been achieved in cw operation and 24 microJ per pulse (35 ns) in the Q-switched regime. Intracavity second-harmonic generation in the pulsed regime is also demonstrated with 17 8 mW of average output power at 439.5 nm, corresponding to an energy of 17microJ per pulse.     

Efficient stable simultaneous CW dual-wavelength diode-end-pumped Nd :YAG laser operating at 1.319 and 1.338 μm

An efficient, stable diode-end-pumped simultaneous continuous-wave (CW) dual-wavelength laser operating at 1.319 and 1.338 μm in a Nd:YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at an absorbed pump power of 15 W, with a slope efficiency of 43.5%. The instability of output power is less than 1%. With a type Ⅱ critical phase-matched KTP crystal inserted into the cavity as frequency doubler, a maximum output power of 200 mW in red region is acquired. In addition, a sixwavelength laser operation at 1.319 μm, 1.338 μm, 1.356 μm, 659.5 nm, 669 nm, and 678 nm is observed.     

High-power Yb-doped continuous-wave and pulsed fibre lasers

High-power laser generation using Yb-doped double-clad fibres with conversion efficiencies in excess of 80% have attracted much attention during the last decade due to their inherent advantages in terms of very high efficiency, no misalignment due to in-built intracore fibre Bragg gratings, low thermal problems due to large surface to volume ratio, diffraction-limited beam quality, compactness, reliability and fibre-optic beam delivery. Yb-doped fibres can also provide a wide emission band from ～1010 nm to ～1170 nm, which makes it a versatile laser medium to realize continuous-wave (CW), Q-switched short pulse, and mode-locked ultrashort pulse generation for various applications. In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical mechanisms involved in its generation has been described. A study on the generation of high-power CW fibre laser of 165 W output power and generation of high peak power nanosecond pulses from acousto-optic Q-switched fibre laser has also been presented.     

High-power continuous-wave upconversion fiber laser at room temperature

We report cw laser emission of a Pr, Yb-doped ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF fiber in the red spectral region. Laser emission was achieved on the transition P(0)(3)?F(2)(3)(lambda(L)=635 nm) with a Ti:sapphire pump laser tuned to lambda(p)=850 nm . A maximum output power of P(out)=675 mW was obtained at an incident pump power of P(in)=3.37 W . The output power was increased to P(out)=1020 mW when pumping with P(in)=5.51 W was provided by two Ti:sapphire lasers. A photon avalanche process was found to contribute strongly to the population of the upper laser level.     

氢化非晶硅薄膜退火形成的纳米硅及其光致发光

本文报道对氢化非晶硅(a-Si:H)薄膜在600～620℃温度下快速退火10s可以形成纳米晶硅(nc-Si),其Raman散射表明,在所形成的nc-Si在薄膜中的分布是随机的,直径在1.6～15nm范围内,并且在强激光辐照下观察了nc-Si在薄膜中的结晶和生长情况.经退火所形成的nc-Si可见光辐射较弱,不能检测到它们的光致发光(PL),但用氢氟酸腐蚀钝化后则可检测到较强的红PL,并且钝化后的nc-Si在空气中暴露一定的时间后,其辐射光波长产生了蓝移.文中就表面钝化和量子限制对可见光辐射的重要性作了讨论.     

All-solid-state CW Nd:GdVO<Subscript>4</Subscript>-LBO red laser under direct 912 nm pumping

We report a red laser at 670.5 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1341 nm Nd:GdVO₄ laser under in-band diode pumping at 912 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 8.9 W, as high as 347 mW of CW output power at 670.5 nm is achieved. The fluctuation of the red output power was better than 3.7% in the given 30 min, and the beam quality factor M ² is 1.65.