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超短激光脉冲可直接诱导透明材料的多光子吸收上转换荧光过程,它在红外探测、新型激光器、海底光学通信、高密度存储以及三维立体显示等前沿的国防和工业科技领域有着广泛的应用。上转换过程的研究目前主要集中在稀土离子和过渡金属离子能级跃迁的机制上,随着机制材料以及受激离子的不同,光子跃迁的机制也不完全相同,因此上转换机制始终伴随着新材料的出现而发展。介绍了上转换过程的种类,将多光子吸收上转换过程用依次吸收与同时吸收进行分类,给出了在实验研究中分辨上转换过程的方法,并讨论了多光子同时吸收的双光子与三光子过程的研究进展和应用,为今后研究不同光功能材料的多光子吸收过程和应用提供了理论依据。 相似文献
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超短激光脉冲的研究已经成为基础科学与应用科学研究的重要内容,对用于检测这种信号的光电发射功能薄膜材料的研究也受到人们极大重视。Ag-Ba-O薄膜是一种可以经历暴露大气,用于超短激光脉冲检测的新型光电发射材料。光电薄膜在超短激光脉冲作用下的量子产额测量与普通可见光作用下量子产额的测量有很大不同。当激光波长为1.06μm,激光的功率密度为107~108W/cm2,选单光脉冲宽度为40Ps时,经历暴露大气的Ag-Ba-O薄膜光电量子产额为10-6数量级。这种薄膜经历暴露大气后,可见光的积分灵敏度全部损失,但在1.06μm激光作用下恢复,光电量子产额不比未暴露大气的样品低。这为Ag-Ba-O薄膜应甲于红外超短激光脉冲的检测奠定了基础。 相似文献
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用于超短激光脉冲检测的新型光电薄膜的量子产额 总被引:1,自引:0,他引:1
超短激光脉冲的研究已经成为基础科学与应用科学研究的重要内容,对用于检测这种信号的光电发射功能薄膜的研究也受到人们极大重视。Ag-Ba-O薄膜是一种可以经历暴露大气,用于超短激光脉冲检测的新型光电发射材料,光电薄膜在超短激光脉冲作用下的量子产测量与普通可见光作用下量子产额的测量有很大不同。光激光波长为1.06μm,激光的功率密度为10^7-10^8W/cm^2,选单光脉冲宽度为40ps时,经历暴露大 相似文献
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分析了实际光学薄膜与其块状材料在微观结构及宏观尺寸上的差异,指出了单光子吸收电离与雪崩倍增可分为两个相对独立的先后过程处理,提出了实际光学薄膜激光诱导损伤的单光子吸收电离引发电子雪崩模型,讨论了原初电子数密度与入射激光波长的关系,以及实际光学薄膜激光诱导损伤阈值与其原初电子数密度的关系,提出了确定原初电子数密度的实验方法。 相似文献
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Laser-induced backside wet etching (LIBWE) is performed using ultrashort 248?nm laser pulses with a pulse duration of 600?fs to obtain sub-wavelength laser-induced periodic surface structures (LIPSS) on the back surface of fused silica which is in contact with a 0.5?mol?l(-1) solution of pyrene in toluene. The LIPSS are strictly one-dimensional patterns, oriented parallel to the polarization of the laser radiation, and have a constant period of about 140?nm at all applied laser fluences (0.33-0.84?J?cm(-2)) and pulse numbers (50-1000 pulses). The LIPSS amplitude varies due to the inhomogeneous fluence in the laser spot. The LIPSS are examined with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Their power spectral density (PSD) distribution is analysed at a measured area of 10?μm × 10?μm. The good agreement of the measured and calculated LIPSS periods strongly supports a mechanism based on the interference of surface-scattered and incident waves. 相似文献
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Localized CO2 laser damage repair of fused silica optics 总被引:1,自引:0,他引:1
A technique has been developed for the localized treatment of laser damage sites in fused silica optics by CO2 laser melt-flow smoothing, by using a 50 to 125 microm diameter beam in a regime that avoids mass removal by ablation. A detailed calibration of the laser irradiance for the threshold ablation of craters was carried out for a range of beam diameters and pulses in the 20 micros to 200 ms range. The results agree with a thermal model that also provides estimates of the melt depth for the different irradiation conditions. Smoothing trials for glass melting at irradiance values just below the ablation threshold irradiance were conducted to determine the optimum conditions and limits for the smoothing process. The technique has been found to remove damage pits up to a depth of 0.5 microm, while the small melt depth associated with localized treatment limits the smoothing to a 相似文献
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S. Heidrich E. Willenborg C. Weingarten A. Temmler 《Materialwissenschaft und Werkstofftechnik》2015,46(7):668-674
With laser polishing, the roughness of ground glass surfaces can be significantly reduced. With process speeds up to 1 cm2/s independent of the processed surface shape, the resulting roughness is already sufficient for illumination optics. To further reduce the roughness, the polishing process itself will be optimized and moreover combined with a subsequent laser based form correction. Within this paper, results of laser polishing as well as laser form correction and combination of the two processes are presented and discussed. 相似文献
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Milasinovic S Liu Y Bhardwaj C Blaze M T M Gordon RJ Hanley L 《Analytical chemistry》2012,84(9):3945-3951
Experiments were performed to examine the feasibility of mass spectrometry (MS) depth profiling of animal tissue by ~75 fs, 800 nm laser pulses to expose underlying layers of tissue for subsequent MS analysis. Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) was used to analyze phospholipids and proteins from both intact bovine eye lens tissue and tissue ablated by ultrashort laser pulses. Laser desorption postionization mass spectrometry (LDPI-MS) with 10.5 eV single photon ionization was also used to analyze cholesterol and other small molecules in the tissue before and after laser ablation. Scanning electron microscopy was applied to examine the ablation patterns in the tissue and estimate the depth of the ablation craters. Ultrashort pulse laser ablation was found to be able to remove a layer of several tens of micrometers from the surface of eye lens tissue while leaving the underlying tissue relatively undamaged for subsequent MS analysis. MS analysis of cholesterol, phospholipids, peptides, and various unidentified species did not reveal any chemical damage caused by ultrashort pulse laser ablation for analytes smaller than ~6 kDa. However, a drop in intensity of larger protein ions was detected by MALDI-MS following laser ablation. An additional advantage was that ablated tissue displayed up to an order of magnitude higher signal intensities than intact tissue when subsequently analyzed by MS. These results support the use of ultrashort pulse laser ablation in combination with MS analysis to permit depth profiling of animal tissue. 相似文献
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在紫外激光条件下对熔石英样品输入输出面进行了损伤阈值测试,测试结果表明熔石英样品输入面损伤阈值是输出面的1.25倍.其损伤形貌基本表现为小麻孔聚集和烧蚀疤痕,表明其损伤由激光驻波场和烧蚀共同引起,并用激光压力模型对其损伤机理进行了分析. 相似文献
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Jianhua Xu Xingze Lu Hongbing Chen Liying Liu Wencheng Wang Congshan Zhu Fuxi Gan 《Optical Materials》1997,8(4):243-247
The influence of electric of poling conditions on the optical nonlinearity of fused silica has been investigated by the second harmonic generation (SHG) technique. The SHG intensity of the poled fused silica increased monotonically with increasing the poling voltage or poling time, and reached a maximum at a poling temperature of T = 250°C, but the SHG intensity decreased quickly as the thermal erasure time increased. The experimental results have been explained using an electric field induced dipole orientation model. 相似文献
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With tightly focused femtosecond laser pulses, waveguides are fabricated in fused silica. The guiding and attenuation properties of these waveguides at wavelengths of 514 nm and 1.5 microm are studied. We demonstrate that by changing only the writing speed, waveguides with a controllable mode number can be produced. 相似文献
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We reported a new approach to the fabrication of three-dimensional refractive-index-modified microstructures inside transparent materials by combining two-dimensional writing by scanning the focus of the femtosecond laser pulse and by forming the long filament in the third dimension. In this way, embedded diffractive beam shapers of grid, square, and ring gratings were obtained in the bulk of fused silica by use of a femtosecond laser with a wavelength of 810 nm and a repetition rate of 1 KHz. These structures and their refractive efficiencies were optimized by selection of the appropriate fabrication parameters, including the pulse energy, grating period, scanning speed, and scanning repetition. The good performance of these devices indicates that, owing to its simple and flexible method for fabricating complex phase elements inside transparent materials, this technique has potential applications to integrated optics. 相似文献
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We report a new technique for the rapid fabrication of microstripe cylindrical and toroidal mirrors with a high ratio (>10) of the two principal radii of curvature (RoC1/RoC2), and demonstrate their effectiveness as mode-selecting resonator mirrors for high-power planar waveguide lasers. In this process, the larger radius of curvature (RoC1) is determined by the planar or cylindrical shape of the fused silica substrate selected for laser processing, whilst the other (RoC2) is produced by controlled CO2 laser-induced vaporization of the glass. The narrow stripe mirror aperture is achieved by applying a set of partially overlapped laser scans, with the incident laser power, the number of laser scans, and their spacing being used to control the curvature produced by laser evaporation. In this work, a 1?mm diameter laser spot is used to produce grooves of cylindrical/toroidal shape with 240?μm width and 16?mm length. After high reflectance coating, these grooves are found to provide excellent mode selectivity as resonator mirrors for a 150?μm core Yb:YAG planar waveguide laser, producing high brightness output at more than 300?W. The results show clearly that the laser-generated microstripe mirrors can improve the optical performance of high-power planar waveguide lasers when applied in a low-loss mode-selective resonator configuration. 相似文献