Nd:Y3Al5O12单晶及纳米粉体的Raman光谱分析

测量了YAG(Y3Al5O12)/Nd:YAG单晶、Nd:YAG前驱物及其在不同温度下煅烧获得粉体的拉曼光谱,对谱峰的振动模式进行了指认,对结果进行了分析.Nd:YAG前驱物在煅烧时,有一个由非晶态向晶态的转化过程;700℃下烧结前驱物获得非晶态产物的结构中含有AlO4四面体结构;随着煅烧温度的升高,拉曼光谱的变化主要表现在两个方面:一是谱峰半高宽(FWHM)减小,谱峰强度增大;二是一些拉曼光谱谱峰发生了频移,这是纳米多晶粉体的界面组元的有序度提高所致.另外,800℃下煅烧获得的Nd:YAG纳米粉体的品格振动模式与Nd:YAG晶体的晶格振动模式存在差异,这是纳米多晶粉体的界面组元的贡献所致.     

Range and Line Resolved Brillouin Scattering in Pure Water Using Pulsed Nd：YAG Laser

ＲａｎｇｅａｎｄＬｉｎｅＲｅｓｏｌｖｅｄＢｒｉｌｌｏｕｉｎＳｃａｔｔｅｒｉｎｇｉｎＰｕｒｅＷａｔｅｒＵｓｉｎｇＰｕｌｓｅｄＮｄ：ＹＡＧＬａｓｅｒ￥ＬＩＵＤａｈｅ；ＱＵＡＮＸｉａｏｈｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓ，ＴｅｘａｓＡ＆ＭＵｎｉ...     

GaAs衬底的固态杂质源脉冲1.06μm激光诱导扩散

利用１．０６αｍ脉冲Ｎｄ：ＹＡＧ激光，以含Ｚｎ的固态杂原在化合物半导体ＧａＡｓ基片上进行诱导扩散，作出了Ｐ－Ｎ结。获得了亚微米的的散结结深及１ｃｍ＾－３量级的表面掺杂浓度，并利用二次离子质谱仪对扩散样品进行成发的逐层扫描分析，研究了结深和掺杂浓度与辐照激光脉冲数，单脉冲数激光能量密度的关系。     

A Compact 532-nm Source by Frequency Doubling of a Diode Stack End-Pumped Nd：YAG Slab Laser

A near-diffraction-limited green source is generated at 1 kHz repetition rate by frequency doubling of a diode stack end-pumped electro-optically Q-switched Nd：YAG slab laser. We obtain 9. 7mJ green light with pulse width of 12.2ns at a repetition rates of i kHz. The pump to green optical conversion efficiency is 12.9%. The energy pulse stability at 532nm is about 0.8%.     

Thermal mode-switching of a passively Q-switched microchip Nd:YAG laser

In the present article, the thermal distribution inside the gain medium of a passively Q-switched microchip laser is modeled and simulated for actual practical values associated with an available microchip laser constructed in our laboratory. The effects of the non-uniform heat distribution on the spectral properties of the output laser beam have been investigated and simulated with the variation of diode-pump power and pulse repetition rate. It is observed that the gain bandwidth as well as Optical Path Difference (OPD) values of the propagating pulses are significantly decreased, while the Nd:YAG chip is cooled down to a certain value. The validity of the utilized model is checked by setting and characterizing the spectral properties of a fabricated laboratory microchip laser under different heating conditions. It is verified that when the temperature of the gain material is changed by an electronically controlled Peltier device, the spectrum of the output laser beam can be switched between single- and dual-mode situations. This physical character has shown good agreement between the presented model and obtained experimental results.     

激光二极管端面连续抽运的Cr4+∶Nd3+∶YAG微片激光器输出特性研究

报道了腔长为 1.1mm的激光二极管端面抽运的Cr4 +∶Nd3 +∶YAG自调Q微片激光器 ,连续抽运下获得了平均功率为 5～ 18mW、重复频率为 1～ 10kHz的稳定的调Q激光脉冲输出序列。并且对微片激光器的调Q输出激光的单脉冲特性参量、重复频率以及抽运阈值功率等进行了理论研究 ,计算结果和实验结果比较吻合。     

Experimental Investigation of Thermal Lensing in End-pumped Nd:YVO4 Crystal Using a New Simple Approach

The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal. There exists a critical point between stable state and unstable state at which the thermally focusing point falls on the surface of one end mirror. Based on this fact, a new method for measuring the thermal focal length has been presented, and applied to three different Nd3+-doped (2%, 0.8%, and 0.5% ) Nd∶YVO4 crystals at various absorbed pump power levels up to 10 W, the results show a good agreement with those of theoretical calculation. It also indicates that the thermal lensing is strongly dependent on the Nd3+-doped concentration, and is affected by crystal surface temperature, especially in the situation of weak thermal lensing.     

Passive Q-switching of Pulsed and CW Nd: YAG Lasers with Cr~(4 ): YAG

Ｐａｓｓｉｖｅ　Ｑ－ｓｗｉｔｃｈｉｎｇ　ｏｆ　Ｐｕｌｓｅｄ　ａｎｄ　ＣＷ　Ｎｄ：ＹＡＧ　Ｌａｓｅｒｓ　ｗｉｔｈ　Ｃｒ￣（４＋）：ＹＡＧＰａｓｓｉｖｅＱ－ｓｗｉｔｃｈｉｎｇｏｆＰｕｌｓｅｄａｎｄＣＷＮｄ：ＹＡＧＬａｓｅｒｓｗｉｔｈＣｒ￣（４＋）：ＹＡＧ...     

Pulsed Nd:YAG laser depositions of ITO and DLC films for OLED applications

Indium-tin oxide (ITO) films deposited on heated and non-heated glass substrates by a pulsed Nd:YAG laser at 355 nm and ∼2.5 J/cm² were used in the fabrication of simple organic light-emitting diodes (OLEDs), ITO/(PVK + Alq₃ + TPD)/Al. The ITO was deposited on heated glass substrates which possessed resistivity as low as ∼3 × 10⁻⁴ Ω cm, optical transmission as high as ∼92% and carrier concentration of about ∼5 × 10²⁰ cm⁻³, were comparable to the commercial ITO. Substrate heating transformed the ITO microstructure from amorphous to polycrystalline, as revealed by the XRD spectrum. While the polycrystalline ITO produced higher OLED brightness, it was still lower than that on the commercial ITO due to surface roughness. A DLC layer of ∼1.5 nm deposited on this ITO at laser fluence of >12.5 J/cm² improved its device brightness by suppressing the surface roughness effect.     

Thermal optimization and erasing of Nd:YAG proton beam written waveguides

We report on how the optical and structural properties of Nd:YAG proton beam written waveguides are modified when they experienced annealing treatments from 50 °C to 950 °C. The microstructural changes caused in the vicinity of the nuclear damage region were found to be stable up to 700 °C, so that higher annealing temperatures lead to a complete waveguide erasing. Before this "erasing" temperature, the partial thermal-induced defect recombination reduces the propagation losses, reaching its minimum value (below 1 dB/cm) after a 400 °C thermal annealing.     

Analysis of Bulk Radiative Heat Transfer in a Crystal and in a Melt Using Numerical Simulation of the Sapphire Crystal Growth by the Stepanov Method

Technical Physics - The effect of bulk radiative heat transfer during the growth of profiled sapphire crystals from the melt is studied by the numerical simulation method. The peculiarities in the...     

变截面折流杆换热器的流动与传热分析

本文在折流杆换热器的基础上,采用数值计算的方法,以水为流动介质,对不同折流杆间隔的折流杆式换热器进行流动与传热特性的分析。同时,本文设计了一种新型的变截面折流杆式换热器,对换热器进行优化,结果表明,变截面折流杆换热器比等截面折流杆换热器的综合性能最多高13%～14%。     

nc-Si/SiNx超晶格薄膜实现Nd:YAG激光器调Q和锁模

采用射频磁控反应溅射法制备a-Si/SiNx超晶格薄膜材料,热退火后形成纳米Si晶粒。把nc-Si/SiNx薄膜作为饱和吸收体插入Nd:YAG激光器腔内,在腔长较短时,实现1.06μm激光的被动调Q运转,获得最小脉宽23ns的调Q单脉冲输出,当腔长增加到124cm时,获得平均脉宽35ps的锁模脉冲序列。根据实验现象结合薄膜结构,分析了材料调Q与锁模的产生机制,并研究了不同工作条件下的调Q输出性能。     

Experimental Design and Methodology for Estimation of Local Heat Transfer Coefficient in Jet Impingement Using Transient Inverse Heat Conduction Problem

Abstract

This article aims to employ a two-dimensional inverse heat conduction technique in designing an experiment for accurately estimating the local convective heat transfer coefficient in slot jet impingement, given temperature measurements at some interior locations in the target plate. The method uses a sequential procedure together with the Beck function specification approach. Solution accuracy and experimental errors are examined using simulated temperature data. It is concluded that a good estimation of the space variable heat transfer coefficient can be made from the knowledge of the transient temperature recordings. The technique is used in a series of numerical experiments to provide the optimum experimental design for a slot jet impingement heat transfer investigation.     

Pulsed laser deposition process of PLZT thin films using an infrared Nd:YAG laser

Pulsed laser depositions of PLZT thin films were performed using an Nd:YAG (1064 nm) laser. The growths took place in vacuum or in an oxygen background. Room temperature and 500 °C were the used substrate temperatures. The X-ray diffraction analysis revealed a preferential crystallographic orientation in the films grown at room temperature in vacuum. Such result is discussed. The velocity distribution functions of the species in the plasma plume were obtained from a time of flight study using optical emission spectroscopy. The maximums of these distributions functions fall around 10⁶ cm/s, equivalent to an energy range of 18-344 eV. Ionic species of heavy elements (like lead) achieved higher velocities than other lighter species. This result is linked to the creation of an accelerating spatial charge and to the thermal nature of the target material extraction that allows some elements to be released first than others. Chemical state variations of the elements present in the films were analyzed. Under these different growing conditions, lead chemical states varied the most.     

飞秒激光热反射实验系统测量金属薄膜中的超快速热传递过程

飞秒激光热反射技术已经成为研究不同材料中超快速热传导过程的有效实验方法.实验中采用前表面加热、后表面探测的方法对不同厚度的Au薄膜进行了测量,通过比较表面电子温度可以得到超快速激光加热条件下Au薄膜材料中电子温度振荡的传递速度.结果表明瞬态条件下非平衡态电子是热量的主要载体,根据实验测量值拟合得到的能量传递速度接近于非...     

Experimental Investigation of Thermal Lensing in End-pumped Nd:YVO4 Crystal Using a New Simple Approach

The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal. There exists a critical point between stable state and unstable state at which the thermally focusing point falls on the surface of one end mirror. Based on this fact, a new method for measuring the thermal focal length has been presented, and applied to three different Nd3+-doped (2%, 0.8%, and 0.5% ) Nd:YVO4 crystals at various absorbed pump power levels up to 10 W, the results show a good agreement with those of theoretical calculation. It also indicates that the thermal lensing is strongly dependent on the Nd3+-doped concentration, and is affected by crystal surface temperature, especially in the situation of weak thermal lensing.     

Analysis of a separate 1319 and 1338 nm Nd:YAG laser with a blazing grating

We develop a separate 1319 and 1338 nm Nd:YAG laser system with a blazing grating (600 lines/mm). The resonator of this system has a Littrow grating configuration and a highly reflective mirror, in which the zero-order diffraction of the grating acts as the laser output. By virtue of the wavelength-dependent reflectivity of the grating, a single-wavelength laser at 1319 nm or 1338 nm can be realized. In view of the laser rate equations and using the distribution of the blazing grating, we analyze the oscillation conditions providing single-wavelength laser operation in the system.     

双棒串接Nd∶YAG激光器的稳区分析和实验研究

用传输矩阵法理论分析了在含热致双折射补偿和不含热致双折射补偿两种情况下,r偏振和偏振对双棒串接激光器谐振腔稳区的影响.选用低掺杂浓度的Nd∶YAG棒,实验上用含90°石英旋光片的双棒对称平行平面短腔获得了最佳实验结果.1 064 nm激光最高输出功率达482.3 W,对应光-光转换效率为40.2％.