高功率准连续激光二极管抽运的Nd：YVO4激光器

对高功率准连续激光二极管端面抽运的Nd:YVO4固体激光器进行了实验研究。研究了抽运功率、温度、重复率及输出镜的透过率对激光器输出功率的影响。当激光二极管重复率达到720Hz、抽动功率33.2W时,激光输出最大平均功率为11W。     

高功率准连续激光二极管抽运的Nd¨YVO_4激光器

对高功率准连续激光二极管端面抽运的 Nd:YVO4 固体激光器进行了实验研究。研究了抽运功率、温度、重复率及输出镜的透过率对激光器输出功率的影响。当激光二极管重复率达到72 0 Hz、抽运功率 33.2 W时 ,激光输出最大平均功率为 11W     

高功率毫米波辐照大鼠失能效应的脑电观察

使用高功率8毫米波辐照清醒的大鼠,同时测量其脑电图。用小波进行多分辨分析,将脑电信号分解成各个节律信号,分析其变化。辐照时,大鼠出现了非节律性的高幅δ波,而且在慢波中夹杂着癫痫样放电,这说明大鼠在受到辐照时产生高度节律紊乱,提示了其受到强烈刺激而进入失能状态。大鼠受到辐照时失能期为辐照第(1.3±0.5)s到(17.2±2.3)s,辐照于30 s时结束,第(62.7±2.6)s时,其脑电图开始恢复。结果表明:大鼠受到高功率毫米波辐照时最佳失能发生在表皮温升较快、表皮损伤较轻的时候,过长时间的辐照不会延长其失能时间,反而会导致其损伤加大。因此,应用高功率毫米波的失能效应时须控制一定剂量。     

高功率微波辐照对雄性大鼠生殖细胞的影响

 采用激光扫描共聚焦显微镜观察受不同参数高功率微波辐照后的大鼠精子细胞内Ca²⁺的变化，同时观察了辐照后大鼠的生殖细胞微核率、畸形率、精子数量、存活率和顶体酶反应的变化。实验表明：此条件下的高功率微波辐照对雄性大鼠的生殖细胞微核率和畸形率没有明显的损伤效应，但4×10⁵次脉冲的高功率微波辐照对大鼠的顶体酶反应有较明显的抑制作用，可能通过改变细胞内第二信使的Ca²⁺浓度来影响其生殖细胞功能。     

自调Q、自锁模铒/镱共掺光纤激光器

研究了结构新颖的环形腔铒/镱（Er/Yb）共掺双包层光纤激光器.为了获得高功率激光输出，使用6个激光二极管（LD）同时抽运Er/Yb共掺光纤，采用光纤光栅（FBG）Sagnac环作为波长选择器，得到了中心波长为1548.11 nm、谱线宽度为0.06 nm的窄线宽激光输出；并利用增益光纤作为可饱和吸收体，实现了自调Q、自锁模脉冲输出.当抽运功率为719 mW时，激光器输出自调Q脉冲，脉冲周期为20μs，脉冲宽度为2.8μs，脉冲的平均功率为38.4mW，峰值功率为274.3mW；当抽运功率为3.6 W时，激光器输出自锁模脉冲，脉冲宽度为4ns，平均功率为319 mW，脉冲峰值功率大于10 W，重复频率为7.937 MHz.     

伽马辐照对掺镱光纤材料特性影响的研究

掺镱光纤是高功率激光器的核心材料,但在高能射线辐照后其应用性能会显著下降,因此有必要对掺镱光纤材料在辐照环境下的性能变化进行深入研究。采用改进型化学气相沉积法结合稀土螯合物掺杂制备了系列光纤预制棒及光纤,测试了光纤在不同剂量下射线辐照前后的高功率输出性能,以及光纤预制棒辐照前后的吸收光谱及镱离子荧光寿命。结果表明:小剂量辐照后掺镱光纤的高功率输出显著下降,通过预制棒吸收光谱可看出主要是因为伽马辐照后使掺镱光纤材料中Al的相关缺陷浓度增多,在可见光区域吸收损耗增加。Ce离子的掺杂通过缓减辐致铝氧空位中心(Al-OHC)色心缺陷的增加,减少Yb离子荧光寿命的下降,可在一定程度上抑制高功率掺镱光纤的辐致暗化。     

多芯光子晶体光纤高功率超连续谱光源

分析基于单芯光子晶体光纤的超连续谱光源在提升平均输出功率时所面临的问题,指出采用多芯光子晶体光纤作为超连续谱产生介质是一种实现高功率超连续谱产生的潜在方案。使用自制皮秒光纤激光器泵浦一段国产多芯光子晶体光纤,实现了光谱范围750~1700 nm,平均功率42.3 W的全光纤化高功率超连续谱输出。     

采用国产大模场面积双包层光纤的714W连续光纤激光器

采用两个中心波长约976 nm准直输出的高功率半导体激光模块为抽运源,通过空间滤波和非球面透镜耦合技术,双端抽运长度为21 m的大模场面积国产掺镱双包层光纤,获得了714.5 W的高功率连续激光输出。采用反向抽运,当入纤抽运功率为760 W时,激光输出功率达到501 W;采用双端抽运,当入纤抽运功率为1137 W时,获得了714.5 W的高功率连续输出,光光转换效率为62.8%,斜率效率为67%。     

七芯光子晶体光纤中百瓦量级超连续谱的产生

采用平均功率为141.6 W的皮秒光纤激光泵浦一段国产七芯光子晶体光纤,获得了平均功率为104.2 W、连续光谱覆盖范围从750至1700 nm以上的超连续谱输出.详细研究了超连续光谱随泵浦功率增加的演变过程,并对基于该七芯光子晶体光纤的超连续谱光源的光谱拓展和功率提升潜力进行相关的分析和讨论.该研究结果对高功率超连续谱光源的发展具有一定的参考价值.     

高功率线偏振皮秒脉冲簇Yb光纤激光器

以一个增益调制的分布式布喇格反射结构的半导体激光器为种子源,设计了一个高功率皮秒脉冲簇输出的线偏振掺镱光纤激光器.种子源输出脉冲宽度200ps,重复频率350MHz.在预放大中插入一个基于一级衍射透过的声光调制器实现了皮秒脉冲簇形式的激光输出,脉冲簇的重复频率在10~500kHz范围可调.皮秒脉冲簇激光通过一个基于大模场面积保偏Yb光纤的功率放大级,获得了高功率线偏振激光输出,平均功率83 W,偏振消光比优于15dB.当脉冲簇重复频率固定在100kHz,脉冲簇中同时存在350个子脉冲时,获得峰值功率12kW的皮秒激光输出.与传统连续脉冲输出的激光器相比,该系统能够实现脉冲簇的输出,有利于峰值功率的进一步提高,可应用于激光微加工领域.     

Low-intensity millimeter waves as a novel therapeutic modality

One of the most significant events in contemporary electromagnetic biology is a surge in interest to specific effects of low-intensity millimeter-band radiation (30-300 GHz). Bioeffects of millimeter waves (MMWs) can often occur without any considerable heating of the exposed subject, and biological responses are principally different from those caused by heating. The effects of MMWs often have a sharp, resonance-like dependence on the radiation frequency, but they depend relatively little on the radiation intensity. A brief, low-intensity MMW exposure can change cell growth and proliferation rates, activity of enzymes, state of cell genetic apparatus, function of excitable membranes and peripheral receptors; it can alleviate stress reactions, stimulate tissue repair and regeneration, etc. In Eastern Europe, low-intensity MMWs are widely employed for therapeutic purposes. The method has gained official recognition, and millions of people received MMW therapy for various conditions. While the mechanisms of MMW efficacy remain unclear and their medical usage is mostly empirical, the knowledge accumulated over more than 20 years of MMW therapy merits careful analysis and consideration     

Analysis of Millimeter Wave Power Density Received by Cell Monolayers Inside Culture Dishes

One sort of experiment concerning biological effects of millimeter waves (MMWs) at the cellular level is performed using a culture dish containing a cell monolayer with MMW irradiated from the underneath. For culture dishes with diameters much larger than the wavelength, analysis is carried out with respect to the relationship between the portion of the incident MMW power density (PD) received by the cell monolayer and influencing factors such as the culture dish bottom thickness, MMW wavelength, and the electromagnetic properties of the dish and culture solution. Another analysis is conducted by the FDTD method to reveal the effect of culture dish configuration on MMW PD received by the cell monolayer in a typical culture dish with a diameter not much longer than the wavelength. With the illustrated results, the conclusion is reached that rigorous analysis, precise measurement and accurate calculation of MMW PD should accompany such experiments, and large-diameter culture dishes are more preferred in experiments to small-caliber dishes.     

Improving Performances and Reducing Cost for Power Amplifiers in Millimeter Wave

The high power broadband amplifiers are key devices for millimeter wave system and equipment. The significant progresses for broadband amplifier–high power TWT in MMWs are described. Advanced techniques such as enhancing operating bandwidth, reducing cost, increasing efficiency, improving heat transfer capability, suppressing spurious oscillations and raising beam transmission have been developed. These approaches possess important consult value to designer for MMW power amplifiers.     

Algorithm Analysis of Electromagnetic Wave Power Density Measurement for Millimeter-Wave Irradiators in Bioelectromagnetic Experiments

In experiments exploring effects of millimeter-wave (MMW) irradiation on biological materials where MMW irradiators are used, the electromagnetic wave (EMW) power density (PD) in the vicinity of the irradiators where the biological materials are placed is an important parameter to be considered so as to determine the irradiation dose. The paper provides a practical algorithm to measure the EMW PD in the vicinity of MMW irradiators with relatively high accuracy and precision. Besides theoretically analyzing and designing the measurement algorithm, a computer program aimed at facilitating the computation is provided after solving problems such as applying sampling theorem and Fast Fourier Transform (FFT). The algorithm and the program were fully tested when an experimental measurement of the EMW PD in the vicinity of a typical MMW irradiator was performed.     

Algorithm Analysis on MMW Dosimetry for the Cell Monolayer Cultered in Petri Dish with the FDTD Method

Four algorithms are developed to help the dosimetry study for experiments on millimeter-wave (MMW) biological effects on cells in vitro with the finite-difference time-domain (FDTD) method. Their performances in evaluating the MMW irradiation dose are displayed and compared, including the induced current density and the specific absorption rate (SAR), that are distributed over the cell monolayer cultured in Petri dish. With the discussion on individual characteristics of the algorithms, the conclusion is reached that an appropriate algorithm is essential in providing accurate data on the MMW irradiation dose by way of numerical calculation, which should be considered carefully in related experiments.     

X波段微波辐照致心肌损伤及机理研究

 采用90 W/cm² X波段微波全身一次辐照大鼠10 min，分别于辐照后0，0.5，1，3，6，12，24 h断头处死，取左心室心肌组织，光镜观察心肌组织形态学损伤；TUNEL法检测心肌组织细胞凋亡；RT-PCR检测大鼠心肌组织GSK3β，caspase-9和caspase-3 mRNA表达水平的变化；Western-blot法检测大鼠心肌组织GSK3β蛋白质磷酸化表达水平的变化；Caspase-9分析试剂盒检测心肌组织中caspase-9酶活性。研究结果表明：90 W/cm² X波段微波辐照可上调心肌组织GSK3β基因表达，使其蛋白磷酸化水平降低，解除了磷酸化对其活性的抑制，使GSK3β活性增强，从而参与了X波段微波辐照致心肌细胞凋亡的启动。90 W/cm² X波段微波辐照同时可使大鼠心肌组织中的凋亡相关蛋白激酶caspase-9和caspase-3基因表达上调，caspase-9酶活性增强，从而造成大鼠心肌细胞凋亡过程的启动，因此，GSK-3β及其下游介导的与凋亡相关的信号分子caspase-9和caspase-3的激活可能是X波段微波辐照致大鼠心肌细胞凋亡的重要途径之一。     

The effect of non-contact heating (microwave irradiation) and contact heating (annealing process) on properties and performance of polyethersulfone nanofiltration membranes

In this work the effect of microwave irradiation on morphology and performance of polyethersulfone (PES) membranes was investigated. The membranes were prepared with 20 wt.% of PES by phase inversion method. N,N-dimethylformamide (DMF) and mixture of water and ethyl alcohol (90/10 vol.%) were employed as solvent and coagulant respectively. Polyvinylpirrolidone (PVP) with the concentration of 2 wt.% was selected as pore former. The effects of irradiation time (10, 30, 60, 90, 120 s) and microwave power (180, 360, 720 and 900 W) on structure and performance of membranes were studied. Increasing the irradiation time and power caused variation in permeate flux and ion rejection. Moreover, the effects of annealing processes (60, 70, 80 °C) were studied. Transmembrane pressure was selected around 1.5 MPa for all experiments. Scanning electron microscope (SEM) and atomic force microscope (AFM) were employed to describe the surface morphology of the prepared membranes. The effect of microwave irradiation time in different power revealed alterations in membrane surface morphology and AFM images represented that surface parameters (such as surface roughness) have been changed. The membrane exhibited moderate rejection (47%) and low permeate flux (4.5 kg/m² h) at 80 °C for NaCl solution. The SEM images indicate that the dense skin layer is formed at 80 °C annealing.     

Optimum Design for RF Windows in Millimeter Wave High Power Tubes

The pill-box and block RF windows for millimeter wave (MMW) tubes are presented. The pill-box window is suitable for broadband MMW tubes. And the block window can be used for high power tubes in short MMW. The equivalent circuits for two windows are given. To reach better match characteristics in wider operating bandwidth, the optimum design methods for pill-box and block window in MMW tubes are described in this paper. The testing results show that the theoretic computation is fast and useful accuracy. The design methods possess references value to designer for MMW tubes.