Diode-pumped continuous wave and Q-switched operation of a c-cut Tm,Ho:YAlO3 laser

We report on a diode-pumped, cryogenic and room temperature operation of a Tm,Ho:YAlO3 (c-cut) laser. In a temperature of 77 K, an optical-optical conversion efficiency of 27% and a slope efficiency of 29% were achieved with the maximum continuous-wave (CW) output power of 5.0 W at 2.13 mu m. Acousto-optic switched operation was performed at pulse repetition frequency (PRF) from 1 kHz to 10 kHz, the highest pulse energy of 3.3 mJ in a pulse duration of 40 ns was obtained. In room temperature (RT), the maximum CW power of Tm,Ho:YAlO3 laser was 160 mW with a slope efficiency of 11% corresponding to the absorbed pump power. (C) 2008 Optical Society of America.

Judd-Oflet analysis of spectrum and laser performance of Ho:YAP crystal end-pumped by 1.91-mu m Tm:YLF laser

The Ho:YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho:YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd-Ofelt intensity parameters Omega(2) = 1.42 x 10(-20) cm(2), Omega(4) = 2.92 x 10(-20) cm(2), and Omega(6) = 1.71 x 10(-20) cm(2), this paper calculated the fluorescence lifetime to be 6 ms for I-5(7) -> I-5(8) transition, and the integrated emission cross section to be 2.24 x 10(-18) cm(2). It investigates the room-temperature Ho:YAP laser end-pumped by a 1.91-mu m Tm:YLF laser. The maximum output power was 4.1 W when the incident 1.91-mu m pump power was 14.4W. The slope efficiency is 40.8%, corresponding to an optical-to-optical conversion efficiency of 28.4%. The Ho:YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8 nm.

Synthesis and Luminescent Properties of LaAlO3:RE3+ (RE = Tm, Tb) Nanocrystalline Phosphors via a Sol-Gel Process

LaAlO3:Tm3+ and LaAlO3:Tb3+ phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence, and cathodoluminescence (CL) spectra were utilized to characterize the synthesized phosphors. The XRD results reveal that the fully crystalline pure LaAlO3 Phase can be obtained at 800 degrees C. The FE-SEM image indicates that the phosphor samples are composed of aggregated spherical particles with sizes ranging from 40 to 80 nm. Under the excitation of ultraviolet light (230 nm) and low-voltage electron beams (1-3 kV), the LaAlO3:Tm3+ and LaAlO3:Tb3+ phosphors show the characteristic emissions of Tb3+ (D-1(2)-> H-3(6,4),F-3(4) transitions) and Tm3+ (D-5(3,4)-> F-7(6,5,4,3) transitions) respectively. The CL of the LaAlO3:Tm3+ phosphors have high color purity and comparable intensity to the Y2SiO5:Ce3+ commercial product, and the CL colors of Tb3+-doped LaAlO3 phosphors can be tuned from blue to green by changing the doping concentration of Tb3+ to some extent.

齐40块蒸汽驱井组油层套管应力数值计算

将蒸汽驱汽窜形成的窜流温度场结果引入井筒应力分析模型中,利用有限元分析软件ANSYS进行了井筒在不同约束条件下的应力计算。计算结果表明,最大热应力都发生在套管内壁,且超过了N80套管的热弹性屈服极限,最大热膨胀都发生在温度变化过渡区,当油层上覆盖层为泥页岩时,其热应变达到了2%,远超过材料弹性极限应变0.3%,是诱发热采井套管变形损坏的主要原因。

Femtosecond optical Kerr effect study of Ge(10)AS(40)S(30)Se(20) film

The results of the femtosecond optical heterodyne detection of optical Kerr effect at 805 nm with the 80 fs ultrafast pulses in amorphous Ge10As40S30Se20 film is reported in this paper. The film shows an optical non-linear response of: 200 fs under ultrafast 80 fs-pulse excitation and the values of real and imaginary parts of non-linear susceptibility chi((3)) were 9.0 X 10(-12) and -4.0 X 10(-12) esu, respectively. The large third-order non-linearity and ultrafast response are attributed to the ultrafast distortion of the electron orbits surrounding the average positions of the nucleus of Ge, As, S and Se atoms. This Ge10As40S30Se20 chalcogenide glass would be expected as a promising material for optical switching technique. (c) 2005 Elsevier Ltd. All rights reserved.

端面抽运的Tm:YAP薄片板条激光器的研究

2μm激光器由于其在遥感、雷达和医疗等领域具有重要的应用前景而受到越来越广泛的重视。Tm3+具有长的荧光寿命,且其吸收带与商用的激光二极管相匹配。YAP具有与YAG近似的机械和热性能,其双折射特性使得Tm:YAP激光器可以直接得到线偏振的激光输出,并且可以降低热退偏效应。795nm连续抽运光经透镜组耦合进薄片板条1mm×5mm晶体端面,采用平凹腔结构,分析比较了1%,4%和5%掺杂浓度的Tm:YAP的激光特性。

Passive Q-switching of short-length Tm3+-doped silica fiber lasers by polycrystalline Cr2+:ZnSe microchips

We demonstrate passive Q-switching of short-length double-clad Tm3+-doped silica fiber lasers near 2 mu m pumped by a laser diode array (LDA) at 790 nm. Polycrystalline Cr2+:ZnSe microchips with thickness from 0.3 to 1 mm are adopted as the Q-switching elements. Pulse duration of 120 ns, pulse energy over 14 mu] and repetition rate of 53 kHz are obtained from a 5-cm long fiber laser. As high as 530 kHz repetition rate is achieved from a 50-cm long fiber laser at similar to 10-W pump power. The performance of the Q-switched fiber lasers as a function of fiber length is also analyzed. (c) 2008 Elsevier B.V. All rights reserved.

Tm-doped fibre laser pumped Cr2+: ZnSe poly-crystal laser

Demonstrations of cw lasing in Cr2+:ZnSe poly-crystal are reported. The laser consists of a 1.7-mm-thick Cr2+:ZnSe poly-crystal disc pumped by a Tm-silica double-clad fibre laser at 2050nm. Using a concave high-reflection mirror with a radius of curvature of 500mm as the rear mirror, the laser delivers up to 1030mW of radiation around 2.367 mu m.