Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi
Ente Cassa di Risparmio di Firenze (No. 2014.0770A2202.8861)

1.质量微球的超高系数的制作<ol><li>剥去约1-2厘米使用光学脱衣舞标准单模（SMF）石英纤维关闭其丙烯酸涂料。 </li><li>清洁用丙酮剥离的一部分，它劈开。 </li><li>引进尖端切割在熔接机的一只手臂，并产生了一系列使用拼接控制器电弧放电。从捻接器菜单中选择"手动操作"，设置电弧功率电平值和电弧持续时间分别为60和800毫秒;选择"弧"，并推入下方的"+"。 </li><li>一旦球体正在形成，停止，旋转90°的纤维并重复步骤1.3。 </li><li>重复步骤1.3的至少4倍，以获得约160微米的微球体。重复16次，以获得约260微米的微球体。 注:电弓放电将产生熔合石英玻璃所需要的高熔融温度。该面传热Ë紧张将吸引来自缄口不言纤维尖端的球体;球体的大小成正比弧的拍摄张数，在一个直径约为350微米的饱和的，因为它可以在图1中19所示。旋转确保了谐振器的球形。 </li></ol> 2.绘制一个锥形光纤注意:也需要将光耦合进微谐振器的锥形光纤。微球的大小将决定锥度的腰部。为球体直径大于125微米，锥的直径可以是约3-4微米。为较小的，锥形的直径应较小，表示1-2微米。为了保持损失在较低水平，具有在锥形部分只有一个模式（基波之一），锥形必须绝热（从厚到薄直径逐渐过渡）。绝热锥形部的典型总长度约2厘米。Figu重新2显示了自制装置用于拉动光纤和图3A示出一个典型的腰部区域的显微照片。 <ol><li>一个标准单模（SMF）二氧化硅纤维断用光学汽提塔其丙烯酸涂料的条3-4厘米，并连接光纤端部的激光（输入）和功率计（输出）。可以肯定的剥离带是大约在纤维的中间，而不是在一端。使用，以便裸光纤终止，以便能够连接光纤端部到激光和功率计。放置激光器和上工作台顶部的功率计。 </li><li>放置一个短的氧化铝气缸内的剥离的纤维，纤维的成在拉动过程同时启动两个翻译阶段涂覆端部。 </li><li>加热氧化铝缸（充当烘箱）被氧丁烷火焰高达接近二氧化硅的熔点（约2100℃）的温度下。 </li><li>从OBSE推断锥度的绝热在635纳米工作的激光光的透射的rvation。检查在输出而渐缩，表示没有模式加扰发生均匀的圆形光斑被保留。别拉和退役火焰当传输的功率停止振荡，并随时间变化。 </li><li>胶锥形光纤成形为U的形式，以容纳锥形显微镜载玻片（参见图3B）。使用尺寸76x26x1.2毫米的显微镜载玻片。 </li></ol> 3.小微球的制备注:直径包标准光纤的尺寸下面小编球需要纤维变细以前。用这种方法获得的最小直径为大约25微米。 <ol><li>按照第2节，画一个锥形光纤，拉动直到它打破。 </li><li>按照第1（UHQ微球的制备），但在步骤1.3中的所有步骤，修改熔接机共同的价值观ntroller如下:电弧功率20，燃弧时间1200毫秒。 </li></ol> 4.光耦合到微球注意:我们使用锥形将光耦合到微球和测量微谐振器的共振。 <ol><li> 4.1。制备T状的PVC /铝架在中间的信道。修复微球的残留纤维干用一块神奇的苏格兰威士忌或纸胶带为持有人。钳用两个螺钉保持器与压电致动器和20nm的定位分辨率的平移台。 </li><li>固定粘在载玻片与垂直于微纤维的干的滑动面另一平移台锥形。拼接锥度的端部端接光缆。一端连接至所述可调谐激光二极管，另一个到的InGaAs光电二极管检测器。 </li><li>使用显微镜管长工作距离（&gt; 20毫米）到合作ntrol锥度和微球之间的间隙。为了监测系统在另一个方向上发生在45°的反射镜相对于所述管的方向，以使位置可以控制相对于微球的赤道锥度。 <ol><li>在与锥形纤维接触的微球的赤道位置。 </li></ol></li><li>打开激光，并检查微球的锥度系统的透射光谱中的示波器。 <ol><li>调整CW激光器在1550nm波长工作，直到共振出现。共振可以被认定为洛伦兹形频谱骤降。 </li></ol></li><li>测量磁共振行距（洛伦兹形浸全宽度半最大值）。计算Q因子作为所述泵由谐振线宽划分的频率。 </li><li>降低/提高球体和锥体之间的间隙，改变两谐振的宽度和深度为增加/减少的耦合效率。 </li></ol><p类="jove_title"&gt; 5。受激拉曼散射<ol><li>插入CW激光器在1550纳米和衰减器操作之间的掺铒光纤放大器（EDFA）。 EDFA的工作的波长范围内的1,530-1,570纳米。注意:这将促进激光功率，达到2 W.非线性效应的最大输出功率需要很高的输入功率图4显示了实验装置的草图。 </li><li>连接与终止的光纤电缆将一个3 dBm的分离器的锥形的一端。连接分离器输出光纤到光频谱分析仪，另一个给连接到示波器的光检测器中的一个。 </li><li>调由高向低频率的激光直到与媲美的激光的波长扫描速度的热漂移的谐振被发现。当热自锁20取得的共振的扩大可以看出在示波器上。 </li><li>检查通过锥形传输的输出功率成光频谱分析仪。直到出现拉曼激光线增加动力。它从泵波长在约13.5赫兹失谐。 </li></ol>

<ol>
	<li>Kozyreff, G., Dominguez-Juarez, J. L., Martorell, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non+linear+optics+in+spheres:+from+second+harmonic+scattering+to+quasi-phase+matched+generation+in+whispering+gallery+modes.">Non linear optics in spheres: from second harmonic scattering to quasi-phase matched generation in whispering gallery modes.</a> Laser Photon. Rev. 5 (6), (2011).</li><li>Farnesi, D., Barucci, A., Righini, G. C., Berneschi, S., Soria, S., Nunzi Conti, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+frequency+generation+in+silica+microspheres.">Optical frequency generation in silica microspheres.</a> Phys. Rev. Lett. 112 (9), 093901 (2014).</li><li>Liang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniature+multioctave+light+source+based+on+a+monolithic+microcavity.">Miniature multioctave light source based on a monolithic microcavity.</a> Optica. 2 (1), 40-47 (2015).</li><li>Maker, A. J., Armani, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+Silica+Ultra+High+Quality+Factor+Microresonators.">Fabrication of Silica Ultra High Quality Factor Microresonators.</a> J. Vis. Exp. (65), e4164 (2012).</li><li>Coillet, A., Henriet, R., Phan Huy, K., Jacquot, M., Furfaro, L., Balakireva, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microwave+Photonics+Systems+Based+on+Whispering-gallery-mode+Resonators.">Microwave Photonics Systems Based on Whispering-gallery-mode Resonators.</a> J. Vis. Exp. (78), e50423 (2013).</li><li>Han, K., Kim, K. H., Kim, J., Lee, W., Liu, J., Fan, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+Testing+of+Microfluidic+Optomechanical+Oscillators.">Fabrication and Testing of Microfluidic Optomechanical Oscillators.</a> J. Vis. Exp. (87), e51497 (2014).</li><li>Arnold, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microspheres,+Photonic+Atoms,+and+the+Physics+of+Nothing.">Microspheres, Photonic Atoms, and the Physics of Nothing.</a> American Scientist. 89 (5), 414-421 (2001).</li><li>Chiasera, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spherical+whispering+gallery+mode+microresonators.">Spherical whispering gallery mode microresonators.</a> Laser Photon. Rev. 4 (3), 457-482 (2010).</li><li>Helt, L. G., Liscidini, M., Sipe, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+does+it+scale?+Comparing+quantum+and+classical+nonlinear+optical+processes+in+integrated+devices.">How does it scale? Comparing quantum and classical nonlinear optical processes in integrated devices.</a> J. Opt. Soc. Am. B. 29 (8), 2199-2212 (2012).</li><li>Leach, D. H., Chang, R. K., Acker, W. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimulated+anti-Stokes+Raman+scattering+in+microdroplets.">Stimulated anti-Stokes Raman scattering in microdroplets.</a> Opt. Lett. 17 (6), 387-389 (1992).</li><li>Farnesi, D., Cosi, F., Trono, C., Righini, G. C., Nunzi Conti, G., Soria, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimulated+Antistokes+Raman+scattering+resonantly+enhanced+in+silica+microspheres.">Stimulated Antistokes Raman scattering resonantly enhanced in silica microspheres.</a> Opt. Lett. 39 (20), 5993-5996 (2014).</li><li>Qian, S. X., Chang, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiorder+Stokes+emission+from+micrometer+size+droplets.">Multiorder Stokes emission from micrometer size droplets.</a> Phys. Rev. Lett. 56 (9), 926-929 (1986).</li><li>Lin, H. B., Campillo, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CW+nonlinear+optics+in+droplet+microcavities+displaying+enhanced+gain.">CW nonlinear optics in droplet microcavities displaying enhanced gain.</a> Phys. Rev. Lett. 73 (18), 2440-2443 (1994).</li><li>Spillane, S. M., Kippenberg, T. J., Vahala, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultralow+threshold+Raman+laser+using+a+spherical+dielectric+microcavity.">Ultralow threshold Raman laser using a spherical dielectric microcavity.</a> Nature. 415 (6872), 621-623 (2002).</li><li>Kippenberg, T. J., Spillane, S. M., Vahala, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kerr-Nonlinearity+optical+parametrical+oscillation+in+an+ultrahigh+Q+toroid+microcavity.">Kerr-Nonlinearity optical parametrical oscillation in an ultrahigh Q toroid microcavity.</a> Phys. Rev. Lett. 93 (8), 083904 (2004).</li><li>Hill, S. C., Leach, D. H., Chang, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Third+order+sum+frequency+generation+in+droplets:+model+with+numerical+results+for+third-harmonic+generation.">Third order sum frequency generation in droplets: model with numerical results for third-harmonic generation.</a> J. Opt. Soc. Am. B. 10 (1), 16-33 (1993).</li><li>Kozyreff, G., Dominguez Juarez, J. L., Martorell, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whispering+gallery+mode+phase+matching+for+surface+second+order+nonlinear+optical+processes+in+spherical+microresonators.">Whispering gallery mode phase matching for surface second order nonlinear optical processes in spherical microresonators.</a> Phys. Rev. A. 77 (4), 043817 (2008).</li><li>Jouravlev, M. V., Kurizki, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unified+theory+of+Raman+and+parametric+amplification+in+nonlinear+microspheres.">Unified theory of Raman and parametric amplification in nonlinear microspheres.</a> Phys. Rev. A. 70 (5), 053804 (2004).</li><li>Brenci, M., Calzolai, R., Cosi, F., Nunzi Conti, G., Pelli, S., Righini, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microspherical+resonators+for+biophotonic+sensors.">Microspherical resonators for biophotonic sensors.</a> Proc. SPIE. 6158, 61580S (2006).</li><li>Carmon, T., Yang, L., Vahala, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamical+thermal+behavior+and+thermal+self-stability+of+microcavities.">Dynamical thermal behavior and thermal self-stability of microcavities.</a> Opt. Express. 12 (20), 4742-4750 (2004).</li><li>Kippenberg, T. J., Spillane, S. M., Min, B., Vahala, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theoretical+and+experimental+study+of+stimulated+and+cascaded+Raman+scattering+in+ultrahigh+Q+optical+microcavities.">Theoretical and experimental study of stimulated and cascaded Raman scattering in ultrahigh Q optical microcavities.</a> J. Sel. Quantum Electron. 10 (5), 1219-1228 (2004).</li><li>Bloembergen, N., Shen, Y. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coupling+between+vibrations+and+light+waves+in+Raman+laser+media.">Coupling between vibrations and light waves in Raman laser media.</a> Phys. Rev. Lett. 12 (18), 504-507 (1964).</li><li>Gorodestky, M. L., Pryamikov, A. D., Ilchenko, V. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rayleigh+scattering+in+high+Q+microspheres.">Rayleigh scattering in high Q microspheres.</a> J. Opt. Soc. Am. B. 17 (6), 1051-1057 (2000).</li><li>Arnold, S., Ramjit, R., Keng, D., Kolchenko, V., Teraoka, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microparticle+photophysics+illuminates+viral+bio-sensing.">Microparticle photophysics illuminates viral bio-sensing.</a> Faraday Discuss. 137, 65-83 (2008).</li><li>Ozdemir, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+sensitive+detection+of+nanoparticle+with+a+self+referenced+and+self-heterodyned+whispering+gallery+Raman+microlaser.">Highly sensitive detection of nanoparticle with a self referenced and self-heterodyned whispering gallery Raman microlaser.</a> Proc. Natl. Acad. Sci USA. 11 (37), E3836-E3844 (2014).</li></ol>

The authors declare that they have no competing financial interests. D.F. is a PhD student at the University of Parma.

微球结构紧凑，高效的非线性振荡器和他们很容易制作和处理。锥形光纤可用于耦合，并从共振器抽取/光。能够得到共振造影高达95％和大约3×10 8个 Q因数。 这些制造技术的主要限制是大量生产和集成。纤维的清洁度是两者的微球和锥形关键的，所以是湿度。这两款器件都必须保存在干燥的环境中的长期持久的实验室生活。非常薄的锥度是脆弱的;应十分注意联轴器时服用。关于Q因子，微球大小可以是重要的。在直径范围从50到500微米的微球，Q 1的超过10 10已被证实在真空23。微球体的固有Q由从几种类型的损失贡献确定:固有曲率损失（Q 弧度 ），在残留表面的不均匀性拉曼散射和瑞利散射损耗（后者是尺寸依赖性的，下部的直径的损失越高22），本征材料的损失，并且通过表面污染物引入的损失。 Q 弧度 -1，规模日益扩大消失:它降低除R快-5/2 24我们的微球，范围从直径25〜250微米的有Q值低于Q的Q值的极限真空度值几个数量级获得来自不等5×10 6至3×10 8。 用于微球的制造的其它方法包括使用CO 2或丁烷/ N 2 O炬。在所有的程序，表面张力将绘制融化成二氧化硅球体。这里，该仪器用于熔化纤维的选择只有经济的。 CO2激光器价格昂贵，火把或捻接器使用存在于所有的实验室纤维。锥形也可以通过在玻璃包层和芯的氢氟酸（HF）侵蚀制造。这种方法是非常长;所需的减薄125微米纤维为4微米的锥形约5小时。另一个缺点是缺乏绝热的，HF会侵蚀所有玻璃以相同的速率。 锥度应显示低的损失;否则这将是很难观察到非线性效应。耦合效率也很重要。锥度和微球之间的间隙，将决定的耦合制度。通过轻微失谐从谐振的间隙直接变化，和/或，所述非线性效应既可以提高或降低。 WGMR可以铺平道路非经典光代量子计算的应用程序。原子可以被困住接近其表面的量子电动力学实验和锥度的纤维将允许在恶劣环境的高效运输。 SRS和非典可以用作辐射光谱测量，也为有源传感，因为它已被最近证明25。

回音壁模式谐振器（WGMR）显示两个独特的性能，长的光子寿命和小模体积允许的非线性现象1-3阈值的降低。回音壁模式是由全内反射在该介电空中接口局限于光学模式。而在时间限制涉及腔的品质因数Q的小模体积是由于高空间限制。 WGMR可具有不同的几何形状和有适于获得高Q谐振器4-6中表面张力的空腔，如二氧化硅微球显示出邻近原子级粗糙度，转换在高品质的因素不同的制造技术。这两种类型的约束，为非线性效应的门槛降低显著由于在WGMR里​​面强大的能量堆积。它也允许连续波（CW）的非线性光学器件。 WGMR可以用日来说明È量子数N，L，m和它们的偏振态，与所述氢原子7强烈类比。球面对称性允许在径向和角度依赖性的分离。径向溶液通过贝塞尔函数，角那些由球谐8给出。 石英玻璃是中心对称的，因此，相关的Χ二阶现象（2）的相互作用被禁止。在微球体的表面上，对称的反转被破坏和Χ（2）的现象可观察到1。然而，对于第二次频率产生相位匹配条件比在第三次频率代相当于更成问题，尤其是因为所涉及的波长有很大的不同，分散的作用，可以很重要。二阶相互作用极其微弱。所产生的电力尺度与Q 3，而对于THI三阶相互作用所产生的电能秤带Q 4 9出于这个原因，此工作的重点是三阶非线性光学敏感性Χ（3）相互作用如受激拉曼散射（SRS）和受激反斯托克斯拉曼散射（SARS）的，是在非典探索较少互动10,11。昌12和13坎皮略率先使用的高度非线性材料WGMR但泵浦激光器呈脉冲式，而不是CW滴非线性现象研究。相比于微小液滴的二氧化硅微球14,10和microtoroids 15提供更稳定和健壮平台，获得多的注意，在过去几十年。具体地，二氧化硅微球是非常容易制造和处理。 SRS是，可以在二氧化硅WGMR 14,15很容易地实现，因为达到阈值是足够纯的增益处理。在这种情况下，高circulati纳克的WGMR内强度保证拉曼激光，但对于参数振荡是不充分的。在这些情况下，有效的振荡需要相位和模式匹配，能量和动量守恒定律和所有谐振模式的一个良好的空间重叠必须满足16-18。这是SARS和FWM一般的情况下。

<table border="0" cellpadding="0" cellspacing="0" width="668">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical Fiber</td>
			<td style="width:93px;">Corning</td>
			<td style="width:119px;">SMF28</td>
			<td style="width:240px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fiber coating stripper</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;">T06S13</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fiber cleaver</td>
			<td style="width:93px;">Fitel</td>
			<td style="width:119px;">S325A</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fusion splicer</td>
			<td style="width:93px;">Furakawa</td>
			<td style="width:119px;">S177A-1R</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Butane and Oxygen Gas</td>
			<td style="width:93px;">n/a</td>
			<td style="width:119px;"></td>
			<td>any vendor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Microscope tube</td>
			<td style="width:93px;">Navitar</td>
			<td style="width:119px;">Zoom 6000</td>
			<td>Modular Kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CCD camera</td>
			<td style="width:93px;">n/a</td>
			<td style="width:119px;">N/A</td>
			<td>any will fit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Monitor</td>
			<td style="width:93px;">n/a</td>
			<td style="width:119px;">N/A</td>
			<td>any monitor is valid</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">3-Axis Stage</td>
			<td style="width:93px;">PI Instruments, Thorlabs, Melles</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Assorted posts and mounts</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;"></td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polarization control</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;">FPC030</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Attenuator</td>
			<td style="width:93px;">Throlabs</td>
			<td style="width:119px;">VOA50</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Photodiode</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;">PDA400</td>
			<td>discontinued, replaced by PDA10CS-EC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Oscilloscope</td>
			<td style="width:93px;">Tektronix</td>
			<td style="width:119px;">DPO7104</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical spectrum analyzer</td>
			<td style="width:93px;">Ando</td>
			<td>AQ6317B</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Erbium Doped Fiber Amplifier</td>
			<td style="width:93px;">IPG Photonics</td>
			<td style="width:119px;">EAD-2K-C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tunable Laser</td>
			<td style="width:93px;">Yenista</td>
			<td style="width:119px;">TUNICS</td>
			<td></td>
		</tr>
	</tbody>
</table>

stimulated stokes and antistokes raman scattering in microspherical whispering gallery mode resonators

介电微球可以只灯光和音响，通过高品质因子回音壁模式一的时间长度（WGM）。玻璃微球可以被认为是能量的存储与一个巨大的各种应用:紧凑激光源，高度敏感的生物化学传感器和非线性现象。一种用于微球体和连接系统两者的制造协议中给出。这里所描述的成色剂是锥形的纤维。有效地产生相关的三阶非线性光学敏感性非线性现象Χ（3）三重谐振二氧化硅微球体的相互作用，提出本文。这里报道的相互作用是:受激拉曼散射（SRS），并且包括受激反斯托克斯拉曼散射（SARS）的四波混合过程。的空腔增强现象的证据是由缺乏泵，信号和闲散之间的相关性的给定:一个谐振模式具有存在以获得一对信号和惰。在hyperparametric振荡的情况下，（四波混频和受激反斯托克斯拉曼散射），模式必须满足能量和动量守恒和最后但并非最不重要的，有一个良好的空间重叠。

微球的Q因素制造按照以上描述的协议是在过量10 8（ 图5），用于大直径（&gt; 200微米）和在过量的10 6个为小直径（&lt;50微米）。 95％（接近临界耦合）上述共振对比可以很容易观察到。对于高循环强度，在红外区域下面的非线性效应可以观察到:受激拉曼散射（SRS），级联的SRS 21，受激反斯托克斯拉曼散射（SARS）和四波混频（FWM）和简并四波混频。拉曼增益平等地放大光的前进和后退的方向，创造驻波的SRS和SRS级联。 FWM对的行波。的测量的示例可以在图6和7中可以看出。 FIGURÈ6示出了由100纳米（1608纳米和1,708纳米）分离的两个SRS线和在泵的附近根据所述介质的电子Kerr非线性级联四光子参量过程，对于约50直径的微米的微球，在1,546.6处抽水。在这种情况下，FWM简并，泵的两个光子产生的信号和空载光子。类似的结果在1551纳米（ 图7）抽约98微米直径的微球获得的。这里，拉曼梳子可以看出在1,666.2纳米为中心，以及次级线可以在低效率的泵的附近可以看到（简并四波混频）。另外，反斯托克斯线是在1451纳米的中心，和两个对称边带由10纳米分离。在这种情况下，泵和斯托克斯字段被充分建成，但SARS的效率被相位失配由于交互式字段（泵，斯托克斯和反斯托克斯）之间的交叉相位调制（XPM）的阻碍。在每时<html> FECT相匹配，斯托克斯和反斯托克斯分量将互为镜像。 SARS总是在SRS存在检测，从不在没有SRS，符合布隆伯根和申22的理论相一致。当非典频率是谐振具有空腔模式和相位与所述泵和SRS信号匹配非典强度特别增强。 图8是一个例子。它显示了（分别为1629 nm和1459纳米）90纳米分离的SRS和SARS线和1,613.8纳米，1,645.6纳米，1710纳米，1,727.6 nm和1,745.8纳米中心等SRS线。 图9显示完美的相位匹配的情况下，直径为65微米的1572纳米的泵浦的微球。斯托克斯线1640处居中和反斯托克斯在1490纳米（分离约347厘米频率-1）为中心。 LES / ftp_upload / 53938 / 53938fig1.jpg"/&gt; 图1.微球的尺寸。在一个标准的125微米的电信光纤的末端产生的微球大小，如在光纤熔接电弧拍摄功能。这个数字已经从修改[18]。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig1large.jpg" target="_blank">请点击这里查看一个更大的版本这个数字。</a> <img alt="图2" src="/files/ftp_upload/53938/53938fig2.jpg" /> 图2.绘制一个锥形的纤维。实验装置用于绘制锥形光纤。该纤维是由两个光纤夹具，分别位于一个滑动块上，在两个轨道的顶部保持。结构是便携式的。在块连接到，除了拉光纤的螺丝。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig2large.jpg" target="_blank">请点击此处查看这个大版本</a>数字。 <img alt="图3" src="/files/ftp_upload/53938/53938fig3.jpg" /> 图3.锥型光纤。（A）锥腰光学显微照片。绿色的颜色是由于干涉效应，以及它的均匀性表示沿锥形部分厚度的均匀性。 （B）粘在其U形玻璃支撑的锥形。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/53938/53938fig4.jpg" /> 图4.实验设置 :将信号从一个可调谐二极管激光器（TDL）由EDFA放大，并且，传递一个衰减器和偏振器之后，通过一个锥形光纤的装置射入WGMR。输出信号被分离并送入一个光谱分析仪（OSA）和光电二极管监控信号进入示波器。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图5" src="/files/ftp_upload/53938/53938fig5.jpg" /> 图5.共振。具有耦合到一个4微米的腰部锥形纤维的直径为250微米的二氧化硅球体WGM谐振。红线是用洛伦兹函数最合适的。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图6" src="/files/ftp_upload/53938/53938fig6.jpg" /> 图6. 小微球的非线性光谱。FWM的实验光谱，拉曼级联线直径为50微米的微球。泵是在1,546.6处的峰，级联FWM峰是出现在靠近泵（13毫微米分离）的对称线，而级联拉曼线的在约13.5赫兹（或约100nm）从泵和从自身分离（1608 nm的第一线，1,708纳米的第二行）。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图7" src="/files/ftp_upload/53938/53938fig7.jpg" /> 图7. 超高Q微球的非线性光谱。在直径98微米的微球的泵和SRS梳的附近非典，四波混频的实验光谱。泵在1551 nm处的峰值，退化FWM被看作接近泵。 100纳米分离SRS线在1646处为中心和相应的非典为c在1,451.5处输入。在非典线附近的两个对称线退化FWM。拉曼梳在1,666.2处居中。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig7large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图8" src="/files/ftp_upload/53938/53938fig8.jpg" /> 图8.腔增强SARS谱。直径为40微米的微球SARS的实验频谱。泵在1,539.4纳米为中心，将SRS线在1,629.6毫微米中心和相应的非典在1459处居中。另外SRS线在1,613.8纳米，纳米1,645.6，1710纳米，1,727.6 nm和1,745.8 nm处。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig8large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <imgALT ="图9"SRC ="/文件/ ftp_upload / 53938 / 53938fig9.jpg"/&gt; 图9.完美的相位匹配SRS-SARS，SARS和SRS实验光谱完全相非典-SRS强度比接近1相匹配的微球直径为65微米。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/53938/53938fig9large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators at JoVE.com

Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

刺激斯托克斯和反斯托克斯拉曼散射在微球形回音壁模式谐振器

有效地产生相关的三阶非线性光学敏感性非线性现象Χ（3）三重谐振二氧化硅微球体的相互作用，提出本文。这里报道的相互作用是:受激拉曼散射（SRS），并且包括受激反斯托克斯拉曼散射（SARS）的四波混合过程。

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres ...

stimulated-stokes-antistokes-raman-scattering-microspherical

Nanyang Technological University

Research

JoVE Journal

Engineering

11.2K 次观看.  Enrico Fermi Center. 有效地产生相关的三阶非线性光学敏感性非线性现象Χ（3）三重谐振二氧化硅微球体的相互作用，提出本文。这里报道的相互作用是:受激拉曼散射（SRS），并且包括受激反斯托克斯拉曼散射（SARS）的四波混合过程。 

视频: Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential.
The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 &mu;m) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere coated with a thin layer of uncured PDMS base. In each type of sensor, laser light from the tapered fiber is coupled into the outermost layer that provides high optical quality factor WGM (Q ~ 106). The microspheres are poled for several hours at electric fields of ~ 1 MV/m to increase their sensitivity to electric field.

A high-sensitivity photonic micro sensor was developed for electric field detection. The sensor exploits the optical modes of a dielectric sphere. Changes in the external electric field perturb the sphere morphology leading to shifts in its optical modes. The electric field strength is measured by monitoring these optical shifts.

回音壁模式聚合物微光学电场传感器的发展

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The ...

科研

工程学

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

The customized techniques developed in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators are presented. The protocols to obtain and characterize these resonators are detailed, and an explanation of some of their applications in microwave photonics is given.

基于微波光子系统回音壁模式谐振器

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

Coherent anti-Stokes Raman Scattering (CARS) Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. In this work coherent anti-Stokes Raman scattering microscopy is used to image the surface of tablets during dissolution while UV absorption spectroscopy is simultaneously providing inline analysis of dissolved drug concentration for tablets containing a 50% mixture of theophylline anhydrate and ethyl cellulose. The measurements showed that in situ CARS microscopy is capable of imaging selectively theophylline in the presence of ethyl cellulose. Additionally, the theophylline anhydrate converted to theophylline monohydrate during dissolution, with needle-shaped crystals growing on the tablet surface during dissolution. The conversion of theophylline anhydrate to monohydrate, combined with reduced exposure of the drug to the flowing dissolution medium resulted in decreased dissolution rates. Our results show that in situ CARS microscopy combined with inline UV absorption spectroscopy is capable of monitoring pharmaceutical tablet dissolution and correlating surface changes with changes in dissolution rate.

Coherent anti-Stokes Raman Scattering CARS Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with an intrinsic flow-through dissolution setup to allow in situ and real-time visualization of the surface of pharmaceutical tablets undergoing dissolution. Using this custom-built setup, it is possible to correlate CARS videos with drug dissolution profiles recorded using inline UV absorption spectroscopy.

相干反斯托克斯拉曼散射（CARS）显微可视化药片剂溶出过程中

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This ...

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample.

The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

至尊纳米线和其他维系统的共振拉曼光谱

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the ...

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

制备与表征超导谐振器的

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the ALD process, which has an accuracy of 0.1 nm.

A protocol for the design and fabrication of a novel nanopillar-based split ring resonator (SRR) is presented.

基于纳米柱裂环谐振器的研制为位移电流共振介导太赫兹超材料

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

基于扫描光散射分析器（SLPS）的方法来量化评估来自眼内镜的前向和后向光散射

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

High-speed Continuous-wave Stimulated Brillouin Scattering Spectrometer for Material Analysis

Recent years have witnessed a significant increase in the use of spontaneous Brillouin spectrometers for non-contact analysis of soft matter, such as aqueous solutions and biomaterials, with fast acquisition times. Here, we discuss the assembly and operation of a Brillouin spectrometer that uses stimulated Brillouin scattering (SBS) to measure stimulated Brillouin gain (SBG) spectra of water and lipid emulsion-based tissue-like samples in transmission mode with &lt;10 MHz spectral-resolution and &lt;35 MHz Brillouin-shift measurement precision at &lt;100 ms. The spectrometer consists of two nearly counter-propagating continuous-wave (CW) narrow-linewidth lasers at 780 nm whose frequency detuning is scanned through the material Brillouin shift. By using an ultra-narrowband hot rubidium-85 vapor notch filter and a phase-sensitive detector, the signal-to-noise-ratio of the SBG signal is significantly enhanced compared to that obtained with existing CW-SBS spectrometers. This improvement enables measurement of SBG spectra with up to 100-fold faster acquisition times, thereby facilitating high spectral-resolution and high-precision Brillouin analysis of soft materials at high speed.

We describe the construction of a rapid continuous-wave-stimulated-Brillouin-scattering (CW-SBS) spectrometer. The spectrometer employs single-frequency diode-lasers and an atomic vapor notch-filter to acquire transmission spectra of turbid/non-turbid samples with high spectral-resolution at speeds up to 100-fold faster than those of existing CW-SBS spectrometers. This improvement enables high-speed Brillouin material analysis.

用于材料分析的高速连续波受激布里渊散射光谱仪

Recent years have witnessed a significant increase in the use of spontaneous Brillouin spectrometers for non-contact analysis of soft matter, such as ...

Ultrasonic Fatigue Testing in the Tension-Compression Mode

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on exposing the specimen to longitudinal vibrations on its resonance frequency close to 20 kHz. With use of this method, it is possible to significantly decrease the time required for the test, when compared to conventional testing devices usually working at frequencies under 200 Hz. It is also used to simulate loading of material during operation in high speed conditions, such as those experienced by components of jet engines or car turbo pumps. It is necessary to operate only in the high and ultra-high cycle region, due to the possibility of extremely high deformation rates, which can have a significant influence on the test results. Specimen shape and dimensions have to be carefully selected and calculated to fulfill the resonance condition of the ultrasonic system; thus, it is not possible to test the full components or specimens of arbitrary shape. Before each test, it is necessary to harmonize the specimen with the frequency of the ultrasonic system to compensate for deviations of the real shape from the ideal one. It is not possible to run a test until a total fracture of the specimen, since the test is automatically terminated after initiation and propagation of the crack to a certain length, when the stiffness of the system changes enough to shift the system out of the resonance frequency. This manuscript describes the process of evaluation of materials' fatigue properties at high-frequency ultrasonic fatigue loading with use of mechanical resonance at a frequency close to 20 kHz. The protocol includes a detailed description of all steps required for a correct test, including specimen design, stress calculation, harmonizing with the resonance frequency, performing the test, and final static fracture.

A protocol for ultrasonic fatigue testing in the high and ultra-high cycle region in axial tension-compression loading mode.

拉伸压缩模式下的超声疲劳试验

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on ...

Scattering And Absorption of Light in Planetary Regoliths

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed microscopic particles. The theoretical and numerical methods constitute a framework of Radiative Transfer with Reciprocal Transactions (R2T2). The R2T2 framework entails Monte Carlo order-of-scattering tracing of interactions in the frequency space, assuming that the fundamental scatterers and absorbers are wavelength-scale volume elements composed of large numbers of randomly distributed particles. The discrete random media are fully packed with the volume elements. For spherical and nonspherical particles, the interactions within the volume elements are computed exactly using the Superposition T-Matrix Method (STMM) and the Volume Integral Equation Method (VIEM), respectively. For both particle types, the interactions between different volume elements are computed exactly using the STMM. As the tracing takes place within the discrete random media, incoherent electromagnetic fields are utilized, that is, the coherent field of the volume elements is removed from the interactions. The experimental methods are based on acoustic levitation of the samples for non-contact, non-destructive scattering measurements. The levitation entails full ultrasonic control of the sample position and orientation, that is, six degrees of freedom. The light source is a laser-driven white-light source with a monochromator and polarizer. The detector is a mini-photomultiplier tube on a rotating wheel, equipped with polarizers. The R2T2 is validated using measurements for a mm-scale spherical sample of densely-packed spherical silica particles. After validation, the methods are applied to interpret astronomical observations for asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko (Figure 1) recently visited by the NASA Dawn mission and the ESA Rosetta mission, respectively.

Numerical and experimental methods are presented for multiple scattering of light in discrete random media of densely-packed particles. The methods are utilized to interpret the observations of asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko.

行星光的散射和吸收

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed ...