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1.
A high efficiency and high peak power laser system with short-pulse and good beam quality has been demonstrated by using a master oscillator power amplifier with two-pass amplification configuration. The master oscillator, end-pumped with a fiber-coupled laser diode array, provides low power but excellent beam quality pulses, and the amplifier boosts the pulse energy by orders without significant beam quality degradation. Short pulses of 8.5 ns with energy up to 130 mJ and approximately diffraction limited beam quality have been demonstrated. 相似文献
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Semiconductor fiber temperature sensors have been used widely in many fields, but most of them pick up temperature by measuring the optical intensity of certain fixed narrow-band in absorption spectrum.Furthermore, they are sensitive to the loss of optical intensity and the fluctuation of light source power.The novel temperature measurement system proposed in this paper is based on the semiconductor absorption theory and the spectral analysis of method. To measure temperature, the sensor model detects not the certain narrow-band spectrum but the most spectra of the optical absorption edge. Therefore the measurement accuracy and the stability can be improved greatly. Experimental results are in agreement with theoretical analysis results perfectly. 相似文献
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We propose an approach for tuning the three-dimensional polarization of a focusing subwavelength spot by a high numerical aperture objective. The incident beams are composed of a radially polarized beam, an azimuthally polarized beam, and a linearly polarized beam with three different weighting factors, respectively. A specially designed adjustable amplitude angular selector is also inserted at the back aperture of the objective for tuning the polarization azimuthally. It is shown that any desired overall polarization orientation can be obtained. We calculated the overall polarization orientation in the focal volume. It is found that the polar angle of the overall polarization orientation can be arbitrarily tuned by the combination of a radially polarized beam and a linearly polarized beam with different weighting factors, and the azimuthal angle can be tuned by rotating the orientation of the linearly polarized beam azimuthally. 相似文献
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周期性纳米结构阵列因其独特的光学效应在新型传感技术领域具有巨大的应用潜力,引起人们极大的兴趣。其光学特性依赖于形貌和结构参数,一般可通过调整这些参数来调控其光学性能,而通过外加磁场调节其光学性能鲜有报道。通过气液自组装法制备胶体晶体模板,采用等离子体刻蚀技术实现了对胶体晶体模板结构尺寸的调控。在此基础上,结合磁控溅射技术合成了具有六角周期性排列的亚波长尺寸磁性Co纳米球阵列膜,并研究了其在结构参数和外磁场作用下的光学性质。通过紫外-可见-近红外光反射谱发现,随着刻蚀时间从0 min增加到4.5 min,在可见光波段,光反射峰波长从512 nm蓝移到430 nm,蓝移了82 nm,峰强从10.69%降低到7.96%,减弱了2.73%;在近红外光波段,光反射峰波长从1 929 nm蓝移到1 692 nm,蓝移了237 nm,峰强从10.92%降低到7.91%,减弱了3.01%。通过控制刻蚀的时间,可实现对Co纳米球阵列膜光反射峰峰位和峰强的有效调控。对未刻蚀和刻蚀的Co纳米球阵列膜施加一个垂直的外加磁场,在外磁场作用下,二者的光反射峰峰强均表现出不同程度的增强。随着外加磁场的逐增,未经刻蚀... 相似文献
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(一)为什么研究这个题目和我们对旧法的改进目前我国正处在一个大跃进的时期。在总路线的光辉照耀下,我国的钢铁工业正面临着一个光荣而艰巨的任务。高速钢的生产中,关于钨的炉前快速分析是长期以来存在的一个急待解决的问题。以往,钨的炉前分析一贯采用重量法。分析所需的时间为三十多分钟。这样长的时间对于炉前分析来说是很不够理想的。由于分析速度的缓慢,严重地影响了出钢时间,造 相似文献
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Three-dimensional SiO2 photonic crystals (PhCs) are fabricated on quartz substrates by the vertical deposition method. Scanning electron microscopy measurement reveals that the samples exhibit an ordered close-packed arrangement of SiO2 spheres. It is found that the position of the [111] photonie band gap (PBG) shifts to a long wavelength (red shift) with increasing sphere size. Gap broadening effects are observed due to the presence of defects in the samples. Moreover, the optical properties of the PBG are very sensitive to the annealing temperature. Our results indicate that the optical properties of the PBG can be easily tuned in the visible region by appropriate experimental parameters, which will be useful for practical applications of PhC optical devices. 相似文献