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提出一种在纤式回音壁模式微球谐振腔,并对其温度和折射率传感特性进行研究。首先,分析了不同尺寸的微球腔与光纤结构耦合时的相位匹配情况,以锥形光纤为探针来拾取并移动钛酸钡微球,将其嵌入空心光纤,形成在纤式谐振腔结构,从而在微球中激发回音壁模式,并与空心光纤端面的反射光相互作用,产生法诺共振。实验结果表明,激发的法诺共振峰曲线的斜率高达-99.3 dB/nm。另外,通过实验证明了此结构对温度和折射率均具有较好的传感特性,灵敏度分别为26.8 pm/℃和-244.97 dB/RIU。该谐振腔性能稳定、结构紧凑、加工简单,在纤式的反射结构使其有望在复杂的传感环境中发挥作用。 相似文献
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设计并测试了两种基于微瓶腔结构的温度传感系统。分别基于电弧放电法和自主装法制备了氧化硅材料(SiO2)和紫外光固化胶(UCA)聚合物材料微瓶腔,通过锥形光纤耦合的方式分析了两种微瓶腔基本特性,并测试它们在温度传感中的应用。实验结果表明,SiO2微瓶腔在温度上升时的灵敏度为11.13 pm/℃,在温度下降时的灵敏度为10.25 pm/℃;UCA微瓶腔在温度上升时的灵敏度为111.89 pm/℃,在温度下降时的温度灵敏度为102.02 pm/℃。两者在上升和下降时均保持很好的一致性,尤其UCA微瓶腔温度灵敏度比SiO2微瓶腔提升了10倍。本文传感器具有体积小、价格低、可塑性和重复性好、灵敏度高等优势,在温度传感领域具有潜在应用。 相似文献
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为提高传感器的稳定性和便携性,提出一种基于空心微瓶谐振腔的折射率传感器,对系统进行封装并对其折射率传感特性进行研究。仿真分析不同壁厚下空心微瓶谐振腔径向回音壁模式的光场分布,光场在微瓶内部的占比随着器件壁厚的减少而增加,有利于提高传感灵敏度。为减小空心微瓶谐振腔的壁厚,利用氢氟酸对石英毛细管进行腐蚀,使用光纤熔接机制备了薄壁空心微瓶谐振腔。采用紫外胶将耦合系统封装固定在载玻片上,器件稳定性和便携性得到提升。研究了封装器件在不同折射率匹配液下的传感特性,器件传感灵敏度为26.50 nm/RIU。该传感器具有稳定性强、灵活性高、损耗小等优点,在光微流控折射率检测方面拥有很大的应用潜力。 相似文献
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提出了有关空心微瓶谐振腔的曲率变化模型并且研究了曲率对其传输特性的影响。仿真分析了微瓶谐振腔内回音壁模式的分布情况,随着曲率的增加,微瓶谐振腔对回音壁模式的束缚能力越强,使得内部光场能量也相应增加。通过控制熔接机的放电次数制得不同曲率的空心微瓶谐振腔,并且根据理想气体状态方程,推导了制备工艺中曲率模型,研究了空心微瓶谐振腔的曲率随放电次数的变化趋势。实验结果表明,曲率越大的空心微瓶谐振腔品质因子越高,可达到7.26×105,该结论在提升谐振腔的品质因子方面具有重要价值。 相似文献
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利用有限元数值分析方法研究了椭球状石英毛细管微气泡回音壁模式特性及其折射率传感性能.计算分析了不同半径与内壁厚度情况下空芯和液芯椭球形微气泡模式特征,包括品质因数、有效折射率和能量比等,并探讨了微气泡在高灵敏度和高分辨率折射率传感方面的应用潜能.研究结果表明微气泡膨胀至350μm,且内壁厚度为1μm时分辨率和灵敏度最佳;在该厚度范围附近,微气泡分辨率不会因为半径尺寸的改变而发生太大变化;二阶径向模具有较高品质因数,其灵敏度略高于一阶基模,且使用二阶径向模可降低在制造时对结构壁厚控制精度的要求,可用于实际传感应用中.研究结果对微气泡的进一步实验研制具有理论参考价值. 相似文献
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光学微球腔因其回音壁模式可获得极高的品质因数而受到广泛关注.本文分析了Fabry-Perot腔和微球腔的基本原理,通过CO2激光熔融光纤实验制得了直径为1.2 mm的微球腔,并测试了微球腔和锥形光纤耦合结构的耦合特性.采用典型的PDH稳频系统设计了基于微球腔的稳频系统,分析了用于鉴频的误差曲线的吸收特性和色散特性,对比了不同调制频率、微球腔直径、耦合损耗、传输损耗下与误差曲线斜率的关系.结果表明:耦合状态下最大Q值可达到1.1×108,调节微球腔内横磁模和横电模的转换可优化耦合效率,匹配微球腔和锥形光纤的尺寸得到了径向二阶模式的透射谱,误差曲线效率达到15.4A mW/MHz.球腔在提高PDH稳频技术灵敏度上具有巨大潜力. 相似文献
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We optically characterize nanolayer (<150 nm) formation in situ on a silica microsphere in an aqueous environment by simultaneously following the shifts of whispering-gallery modes at two wavelengths. This approach was inspired by layer perturbation theory, which indicates that these two measurements can be used to determine independently both the thickness and the optical dielectric constant. The theory is verified for extreme cases and used to characterize a biophysically relevant hydrogel nanolayer with an extremely small excess refractive index of 0.0012. 相似文献
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We show that a glass microsphere resonator can be used as a wavelength-selective mirror in fiber lasers. Due to their high quality factor (Q approximately 10(8)), microsphere resonators possess a narrow reflection bandwidth. This feature enables construction of single-frequency fiber lasers even when the laser cavity is long. Nonlinear effects (such as stimulated Raman lasing) were also observed in our setup at relatively low pump powers. 相似文献
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We propose and demonstrate an active Q-switched fiber laser using a high-Q microsphere resonator as the Q-switching element. The laser cavity consists of an Er-doped fiber as the gain medium, a glass microsphere reflector (coupled through a fiber taper) at one end of the cavity, and a fiber Bragg grating reflector at the other end. The reflectivity of the microsphere is modulated by changing the gap between the microsphere and the fiber taper. Active Q switching is realized by oscillating the microsphere in and out of contact with the taper. Using this novel technique, we have obtained giant pulses (maximum peak power approximately 102 W, duration approximately 160 ns) at a low pump-power threshold (approximately 3 mW). 相似文献
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采用嵌入Fabry-Perot谐振腔的方式,研究了Tl2Ba2CaCu2O8(Tl-2212)高温超导薄膜双晶约瑟夫森结的毫米波辐照特性.重点研究了双晶约瑟夫森结与Fabry-Perot谐振腔的耦合特性,发现放置在谐振腔中的结的位置、角度、结的图形以及Fabry-Perot谐振腔中两镜面间的距离等对耦合都有很大的影响.通过精细调节这些参数,可使双晶约瑟夫森结与外加毫米波达到最佳耦合.在最佳耦合情况下,能观察到9级明显的夏皮罗台阶.利用Fabry-Perot谐振腔技术,解决了约瑟夫森结与毫米波的耦合问题,为高温超导约瑟夫森结的毫米波及太赫兹波的辐射和检测研究奠定了基础. 相似文献
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H. Yokoyama T. Sato K. Ono Y. Hirayama S. Tarucha 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):527
Combined quantum wire and quantum dot system is theoretically predicted to show unique conductance properties associated with Coulomb interactions. We use a split gate technique to fabricate a quantum wire containing a quantum dot with two tunable potential barriers in a two-dimensional electron gas. We observe the effects of the quantum dot cavity on the electron transport through the quantum wire, such as Coulomb oscillations near the pinch-off voltage and periodic conductance oscillations on the first conductance plateau. 相似文献
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We investigate the degradation of the Q factor of a fundamental whispering-gallery mode of a microsphere resonator when a fiber tip is placed in the evanescent field of the mode. With a tip diameter of 80 nm it is possible to maintain a Q factor exceeding 10(8), even when the tip is as close as 10 nm to the sphere surface. This result demonstrates the possibility of using such a tip as a "nanotool" to actively place a single nanoparticle in a single high- Q mode with great precision to achieve well-controlled coupling. 相似文献
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Linear stability analysis of capillary instabilities in a thin nematic liquid crystalline cylindrical fiber embedded in an
immiscible viscous matrix is performed by formulating and solving the governing nemato-capillary equations, that include the
effect of temperature on the nematic ordering as well as the effect of the nematic orientation. A representative axial nematic
orientation texture with the planar easy axis at the fiber surface is studied. The surface disturbance is expressed in normal
modes, which include the azimuthal wave number m to take into account non-axisymmetric modes. Capillary instabilities in nematic fibers reflect the anisotropic nature of
liquid crystals, such as the ordering and orientation contributions to the surface elasticity and surface normal and bending
stresses. Surface gradients of normal and bending stresses provide additional anisotropic contributions to the capillary pressure
that may renormalize the classical displacement and curvature forces that exist in any fluid fiber. The exact nature (stabilizing
and destabilizing) and magnitude of the renormalization of the displacement and curvature forces depend on the nematic ordering
and orientation, i.e. the anisotropic contribution to the surface energy, and accordingly capillary instabilities may be axisymmetric or non-axisymmetric.
In addition, when the interface curvature effects are accounted for as contributions of the work of interfacial bending and
torsion to the total energy of the system, the higher-order bending moment contribution to the surface stress tensor is critical
in stabilizing the fiber instabilities. For the planar easy axis, the nematic ordering contribution to the surface energy,
which renormalizes the effect of the fiber shape, plays a crucial role to determine the instability mechanisms. Moreover,
the unstable modes, which are most likely observed, can be driven by the dependence of surface energy on the surface area.
Low-ordering fibers display the classical axisymmetric mode, since the surface energy decreases by decreasing the surface
area. Decreasing temperature gives rise to the encounter with a local maximum or to monotonic increase of the characteristic
length of the axisymmetric mode. Meanwhile, in the presence of high surface ordering, non-axisymmetric finite wavelength instabilities
emerge, with higher modes growing faster since the surface energy decreases by increasing the surface area. As temperature
decreases, the pitches of the chiral microstructures become smaller. However, this non-axisymmetric instability mechanism
can be regulated by taking account of the surface bending moment, which contains higher order variations in the interface
curvatures. More and more non-axisymmetric modes emerge as temperature decreases, but, at constant temperature, only a finite
number of non-axisymmetric modes are unstable and a single fastest growing mode emerges with lower and higher unstable modes
growing slower. For nematic fibers, the classical fiber-to-droplet transformation is one of several possible instability pathways,
while others include chiral microstructures. The capillary instabilities' growth rate of a thin nematic fiber in a viscous
matrix is suppressed by increasing either the fiber or matrix viscosity, but the estimated droplet sizes after fiber breakup
in axisymmetric instabilities decrease with increasing the matrix viscosity.
Received 15 April 2002 and Received in final form 3 October 2002
RID="a"
ID="a"e-mail: alejandro.rey@mcgill.ca 相似文献
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A. Mazzei S. Gtzinger L.de S. Menezes V. Sandoghdar O. Benson 《Optics Communications》2005,250(4-6):428-433
In this paper, we demonstrate a novel method for optimizing the in- and out-coupling of light confined in the fundamental high-Q whispering-gallery mode of a microsphere resonator via an external prism coupler. The technique relies on the use of a near-field probe to map the modes of the resonator and to obtain topographical information at the same time. We demonstrate the feasibility and efficiency of this technique by applying it to a sphere with a radius of 59 μm. 相似文献