共查询到19条相似文献,搜索用时 234 毫秒
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飞秒激光形成的半导体低维结构与发光 总被引:1,自引:0,他引:1
采用飞秒激光辐照硅和硅锗样品,用扫描电子显微镜(SEM)观察样品同,发现样品上产生了某低维结构.用飞秒激光作用产生等离子体相干驻波对硅和硅锗表面的融蚀模型来解释低维结构的形成机制,发现硅的表面周期约为400 nm的光栅结构在波长719 nm处有较强的光致荧光(PL)峰.该光致荧光的发光强度较小,其机制可从激光的脉宽和重复率两个方面来分析.当激光辐照的能量明显超过硅的融蚀阈值时,光栅形状消失,另一种锥状结构开始形成.控制加工条件,可以获得用于衍射和微分束的纳米光栅. 相似文献
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用电子束蒸发的方法在BK7玻璃上制备了ZrO2单层膜和ZrO2/SiO2高反膜,利用掺Ti:sapphire飞秒激光系统输出的中心波长为800 nm,脉宽为50 fs的激光脉冲对这两种样品进行了激光损伤阈值测试.实验结果表明,ZrO2单层膜的阈值比ZrO2/SiO2高反膜的高;这与传统的纳秒脉冲激光的损伤情况相反.利用光离化和碰撞离化激发电子到导带,形成电子等离子体基本模型并对此现象进行了解释.同时,用显微镜对样品的损伤形貌进行了观测,对损伤的特点进行了表征. 相似文献
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采用紫外-可见吸收光谱和电子自旋共振谱(ESR)对硅酸铅玻璃薄膜和体材料受紫外激光照射前后的结构变化进行了研究。研究发现:266 nm的紫外激光照射硅酸铅玻璃体材料时,能使其Urbach能量增大,即玻璃结构的无序性增大。电子自旋共振谱研究表明,266 nm激光照射不会在硅酸铅玻璃中产生顺磁缺陷中心, 也不会对硅酸铅玻璃薄膜在235 nm附近的吸收峰产生影响,但用248 nm紫外激光照射则观察到了235 nm吸收峰的光漂白现象。 相似文献
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JIANG Xiongwei QIU Jianrong ZHU Congshan K.Hirao GAN Fuxi ) Photon Craft Project Shanghai Institute of Optics Fine Mechanics The Chinese Academy of Sciences Shanghai China ) Photon Craft Project ICORP JST Kyoto 《Chinese Journal of Lasers》2001,10(6):422-426
1 Introduction Withthedevelopmentofmultimediaandelectroniccommunicationnetworks,therequirementofdatastorageisincreasingrapidly .Recentyears,intenseresearchactivitiesareundertakingallovertheworldtofindalternatemethodsandrecordingmediatomeettheneedofdat… 相似文献
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A novel method for producing rewritable optical memory with ultra-high storage density and ultra-high recording and readout speed is presented. A 120 fs, 800 nm, 1 kHz laser focused by an objective lens is used to produce recording bits in glass with high transmittance contrast. These recording bits can be erased by heat-treatment. The mechanism has been discussed by means of the absorption and electron spin resonance(ESR) spectra of silicate glasses before and after irradiation by the laser. The absorption of glasses increases greatly after irradiation because of color-center generation through multi-photon absorption. ESR spectra shows that the color-center induced in the glass are hole-trapped defects. The color-center disappears when the glass heated because the holes and electrons at traps are released by thermal stimulation and recombine again. 相似文献
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Kazem Jamshidi-Ghaleh Erik S. LotfiHossein Masalehdan 《Optics and Lasers in Engineering》2011,49(5):605-608
In this paper, the femtosecond laser-induced darkening in SK3 glass is investigated. A sample with 3-mm thickness is irradiated with 200 fs laser pulses (FLP) at 800 nm wavelength and 1 kHz repetition rate. When a piece of quartz or sapphire, which does not show darkening effect under IR irradiations, is placed in front of the sample, the laser-induced darkening is enhanced. The directly darkened region in the sample gets darker on placing a piece of quartz or sapphire in front of the sample. When a piece of ULE glass that shows darkening effect by IR-FLP irradiations is placed in front of the sample, SK3 sample does not get that dark. We believe the enhancement of the darkening in SK3 glass sample by the quartz or sapphire is related to the absorption of the short wavelength component of the white light, which is generated and not absorbed in the quartz or sapphire. 相似文献
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Qing Yang Tao Chen Jinhai Si Tianxing Lin Xun Hou Guodong Qian 《Optics Communications》2008,281(4):831-835
Ultrafast nonlinear optical properties of lead(II) phthalocyanine (PbPc)-doped silica gel glasses were investigated using a femtosecond optical Kerr shutter (OKS) setup at wavelength of 800 nm. The nonlinear response time of the PbPc-doped silica gel glasses was measured to be less than 90 fs. Measurements for the dependence of Kerr signals on the polarization angle between pump and probe beams showed that the Kerr signals induced by 30-fs pulses arose mainly from photoinduced birefringence effect and not from a laser-induced transient grating as observed when using a 200-fs pulse laser. 相似文献
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Haiyi Sun Tianqing Jia Chengbin Li Shizhen Xu Xiaofeng Wang Zhizhan Xu 《Solid State Communications》2007,141(3):127-131
We studied the single-shot damage in magnesium fluoride irradiated by 800 nm femtosecond (fs) laser. The dependence of damage thresholds on the laser pulse durations from 60 to 750 fs was measured. The pump-probe measurements were carried out to investigate the time-resolved electronic excitation processes. A coupled dynamic model was applied to study the microprocesses in the interaction between fs laser and magnesium fluoride. The results indicate that both multiphoton ionization and avalanche ionization play important roles in the femtosecond laser-induced damage in MgF2. 相似文献
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A single-crystal CaF2 (111) was irradiated with single and multiple laser (Ti:sapphire, 800 nm, 25 fs) shots at fluences ranging from 0.25 to 1.5 J cm?2. In this fluence regime, a single laser pulse usually leads to typical bump-like features ranging from 200 nm to 1.5 μm in diameter and 10–50 nm in height. These bumps are related to compressive stresses due to a pressure build-up induced by fast laser heating and their subsequent relaxation. When CaF2 is irradiated with successive (in our case 20) shots at a laser fluence of 1.5 J cm?2, nanocavities at the top of the microbumps are observed. The formation of these nanocavities is regarded as an explosion and is attributed to the explosive expansion generated by shock waves due to laser-induced plasma after the nonlinear absorption of the laser energy by the material. Such kinds of surface structures at the nanometre scale could be attractive for nanolithography. 相似文献
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Sachin D. Kshirsagar Ummar Pasha Shaik M. Ghanashyam Krishna Surya P. Tewari 《Applied Physics A: Materials Science & Processing》2013,111(3):861-865
Laser-induced darkening and crystallization of ZnTe-based thin films is reported. ZnTe thin films of 1500-nm thickness were deposited on bare and Zn buffer layered borosilicate glass substrates. The as-deposited films were subjected to laser irradiation at 532 nm. The as-deposited films were amorphous but transformed to the crystalline state under influence of the laser treatment. The X-ray diffraction patterns revealed that the ZnTe crystallized in the zinc blende structure. In addition, presence of peaks from Te was observed, signifying the dissociation of ZnTe. The spectral transmission of the films decreased by more than 15 % under the influence of the laser irradiation and this was accompanied by a red shift in the band gap. These results clearly point to the occurrence of laser-induced darkening and crystallization of the films. To understand the mechanisms of darkening and crystallization, all the films were annealed at 500 °C for 60 min. Similar to the laser-irradiated samples, the thermally annealed films showed an amorphous–crystalline transition, presence of Te in the X-ray diffraction patterns as well as a large decrease in spectral transmission (>70 %). Photoinduced emission analysis carried out as a function of laser intensities indicated a strong red shift of about 51 meV in emission energy with increase in laser intensity due to the photodarkening. The peak position of the emission spectrum can be tuned by increasing the laser intensity and is completely reversible with decrease in laser intensity. It is proposed that laser-induced darkening occurs due to the dissociation of ZnTe into ZnTe and Te and that crystallization is a consequence of laser annealing. 相似文献
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New germanosilicate glasses giving the crystallization of yttrium iron garnet Y3Fe5O12 (YIG) and Bi-doped YIG, 23Na2O-xBi2O3-(12−x)Y2O3-25Fe2O3-20SiO2-20GeO2 (mol%), are developed, and the laser-induced crystallization technique is applied to the glasses to pattern YIG and Bi-doped YIG crystals on the glass surface. It is clarified from the Mössbauer effect measurements that iron ions in the glasses are present mainly as Fe3+. It is suggested from the X-ray diffraction analyses and magnetization measurements that Si4+ ions are incorporated into YIG crystals formed in the crystallization of glasses. The irradiations (laser power: 32-60 mW and laser scanning speed: 7 μm/s) of continuous wave Yb:YVO4 fiber laser (wavelength: 1080 nm) are found to induce YIG and Bi-doped YIG crystals, indicating that Fe3+ ions in the glasses act as suitable transition metal ions for the laser-induced crystallization. It is suggested that YIG and Bi-doped YIG crystals in the laser irradiated part might orient. The present study will be a first step for the patterning of magnetic crystals containing iron ions in glasses. 相似文献
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TiO2 film of around 850 nm in thickness was deposited on a soda-lime glass by PVD sputtering and irradiated using one pulse of krypton-fluorine (KrF) excimer laser (wavelength of 248 nm and pulse duration of 25 ns) with varying fluence. The color of the irradiated area became darker with increasing laser fluence. Irradiated surfaces were characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Surface undergoes thermal annealing at low laser fluence of 400 and 590 mJ/cm2. Microcracks at medium laser fluence of 1000 mJ/cm2 are attributed to surface melting and solidification. Hydrodynamic ablation is proposed to explain the formation of micropores and networks at higher laser fluence of 1100 and 1200 mJ/cm2. The darkening effect is explained in terms of trapping of light in the surface defects formed rather than anatase to rutile phase transformation as reported by others. Controlled darkening of TiO2 film might be used for adjustable filters. 相似文献