共查询到20条相似文献,搜索用时 547 毫秒
1.
Go Obara Yuto Tanaka Tomoya Miyanishi Minoru Obara 《Applied Physics A: Materials Science & Processing》2011,102(3):551-557
We present localized optical field distribution properties in the vicinity of gold particles on a silicon substrate by backward
and forward irradiation. It is technically difficult to fabricate nanostructures on the surface by a conventional forward
laser incident to the substrate because gold nanoparticles easily aggregate to form double-layered particle arrays. We calculated
enhanced optical field properties in order to pattern the substrate surface only with a template of the bottom-layered particle
arrays in the case that the backward irradiation of a femtosecond laser is used in the system of aggregated double-layered
gold nanoparticle arrays. With the backward irradiation, the optical field intensity in the substrate for the double-layered
hexagonal arrays is found to be only 30% lower than the mono-layered system. Moreover, a near field cannot be generated with
the forward irradiation. As a result, only the backward irradiation scheme is found to be effective for uniform surface nanopatterning
at enhanced plasmonic near-field zones. 相似文献
2.
Huei Pei Kuo Paul Rosenberg Robert Walmsley Sagi Mathai Lennie Kiyama Joseph Straznicky Moray Mclaren Michael Tan Shih-Yuan Wang 《Applied Physics A: Materials Science & Processing》2009,95(4):955-965
We describe two free-space optical links for multichannel optical interconnects. The targeted aggregate data rate is 240 Gb/s.
In one implementation we use a unique implementation of telecentric optics and achieved an optical link that is simple, robust,
and modular. We describe a simple, inexpensive telecentric lens that can accommodate all optical channels within a 1-mm-diameter
sweet zone. We also describe the performance of an optical link with a 4×4 array of VCSELs and matching detectors. The integrity
of the optical link is not significantly degraded with a>±2 mm translational misalignment between the VCSEL and detector arrays. With the telecentric optical link, we need only two
low-bandwidth, single-axis active servomechanisms to compensate for static tilt and possibly low-frequency thermally-driven
shift between the transmitter and receiver arrays. In the other implementaion we use two matching arrays of 1×12 optical fibers.
Data are coupled optically through an air gap of 2 mm by means of a pair of collimating microlens arrays that are aligned
to one another via precision mechanical subassemblies. We describe a simple, inexpensive, and robust mechanical coupling for
the optical link achieved by using miniature high-flux magnets. 相似文献
3.
B. Bellini M. A. Geday N. Bennis A. Spadło X. Quintana J. M. Otón R. Dąbrowski 《Opto-Electronics Review》2006,14(4):269-273
Liquid crystal (LC) phased arrays and gratings have been employed in optical switching and routing [1]. These diffractive
optic elements are of great interest because they can be scaled up to a large number of elements and their optical properties
can be electrically addressed with a low driving voltage. LC phase gratings have been achieved either by periodic addressing
of pixels or by using periodically-modified structures. The latter approach leads to less reconfigurable devices but the addressing
is simpler.
In this paper we focus on optical phased arrays where the phase is varied either continuously or discretely and where the
periodicity is induced by electrode configuration. We first describe a possible structure based on a conductive silicon wafer.
We argue that this structure can induce either continuously or discretely varying arrays while applying single voltage to
the array. In the second part we simulate the behaviour of such arrays. We base the simulation on a LC synthesized at the
Military University of Technology, this high-birefringence nematic LC shows in a 4-μm thick cell a linear phase shift range
of more than 360° between 1.2 V and 1.8 V. We calculate the distribution of the LC molecule director and assess the performance
of the array with respect to the applied voltage. Finally, the relevance of such technology for switchable phased arrays is
discussed. 相似文献
4.
5.
Near-field optical observations of surface plasmon wave interference at subwavelength hole arrays perforated in Au film 下载免费PDF全文
We image optical near-field patterns at subwavelength circular hole arrays in Au film by using scanning near-field optical microscopy in near-infrared wavelengths.Periodical oscillation features are found in the near-field images at the air/Au interface and exhibit two typical kinds of standing wave oscillation forms at the wavelengths corresponding to the transmission minimum and maximum in the transmission spectrum,and the latter one originates from the excitation and interference of a surface plasmon wave at the metallic hole arrays.Our work indicates that monitoring optical near-field patterns can help to reveal many interesting properties of surface plasmon waves at metallic nanostructures and understand their underlying physical mechanisms. 相似文献
6.
We introduce a technique to obtain localization of Bose-Einstein condensates in optical lattices via boundary dissipations. Stationary and traveling localized states are generated by removing atoms at the optical lattice ends. Clear regimes of stretched-exponential decay for the number of atoms trapped in the lattice are identified. The phenomenon is universal and can also be observed in arrays of optical waveguides with mirrors at the system boundaries. 相似文献
7.
T. Miyanishi Y. Tsunoi M. Terakawa M. Obara 《Applied physics. B, Lasers and optics》2012,107(2):323-332
We present near-field distributions around an isolated 800-nm silica or silicon nanoparticle, and nanoparticle arrays of 800-nm silica or silicon nanoparticles, on a silicon substrate by the finite-difference time-domain method when 800-nm light is irradiated obliquely to the substrate. Nanopatterning mediated with the nanoparticle system is promising for large-area, high-throughput patterning by using an enhanced localized near-field ablation by the nanoscattered light lens effect. The irradiation area cannot be extended for silica nanoparticles, because the optical field enhancement factor is low. Gold nanoparticles can generate highly enhanced near fields, although at present there are no useful ways to arrange the gold nanoparticles on the substrate at a high throughput. Silicon nanoparticles with high dielectric permittivity have optical characteristics of both silica and gold nanoparticles. The particle arrangement on the Si substrate is technically easy using a wet pulling process. From the calculation, high optical field intensity is acquired with oblique s-polarized irradiation to the substrate under silicon nanoparticle arrays, and the intensity is almost the same as that under gold nanoparticle arrays under the same condition. With this method, high-throughput nanopatterning for a large area would be achievable. 相似文献
8.
We discover that, at the edge of an optical lattice imprinted in a saturable nonlinear medium, one-dimensional surface solitons exist only within a band of light intensities and that they cease to exist when the lattice depth exceeds an upper threshold. We also reveal the generation of arrays of two-dimensional surface solitons mediated by the transverse modulational instability of one-dimensional solitons, a process that is found to exhibit specific features associated to properties of the optical lattice. 相似文献
9.
We study the phase behavior of two-dimensional paramagnetic colloidal systems on square pinning arrays, the latter being created by a holographic optical tweezer technique. When the particle interaction strength is decreased, a transition from an incommensurate to a commensurate solid is observed. At even smaller pair potentials, the interstitial particles start to melt, whereas the particles at the substrate pinning sites are still localized. Our results are in good agreement with recent numerical studies on vortex melting in periodic pinning arrays. 相似文献
10.
利用Gerchberg-Saxton算法生成任意的二维光晶格阵列的全息图,并且将全息图加载到液晶型空间光调制器上,然后将850 nm的激光照射到空间光调制器的液晶屏上,利用透镜的傅里叶变换特性,成功地显示或构建任意形状的二维光晶格阵列。将该系统应用到87Rb的冷原子实验中,成功俘获冷原子,这为接下来的单原子多量子位的量子模拟实验奠定了基础。 相似文献
11.
Shaolin Ke Jianxun Liu Qingjie Liu Dong Zhao Weiwei Liu 《Optical and Quantum Electronics》2018,50(8):318
We investigate the exceptional points (EPs) in plasmonic waveguide arrays, including metallic waveguide arrays (MWAs) and graphene sheet arrays (GSAs). The EPs emerge at the boundary of strong and weak coupling ranges in both systems. The cross conversion of Bloch modes and variation of geometric phase can be observed by encircling an EP in the parametric space. We also show the Bloch modes exhibit strong absorption in the vicinity of EPs in GSAs, which originates from the enhanced longitude electric field along the propagation direction. The abnormal absorption and field enhancement also arise in ultrathin MWAs and disappear when the thickness of metal film increases. Our results may find applications in optical switches and sensors at the nanoscale. 相似文献
12.
1 Introduction As“wireinterconnection”ofelectroniccomputerhassomeshortagessuchasbottleneck,clockskew,RCconstant,limitedtimespaceproduct,crosstalk,itisdifficulttofurtherimprovetheperformanceofelectronicinterconnectionnetwork.Aslightwavehasthefeature… 相似文献
13.
An optical implementation of CMOS/SEED optoelectronic integrated crossbar interconnection network is reported. The CMOS/SEED smart pixel arrays with O/E light windows are used as logical controlling switch nodes. High/lower modulating ratio of the output light density is about 1.4. The light beam is supplied by a 0.85 μm semiconductor laser diode. 8×2 spot arrays formed by a computer-generated phase grating are used as the pumping light beams for CMOS/SEED light modulators. High-precision 2-D optical fiber bundle arrays are used as the I/O access devices. 16×16 optical crossbar interconnection network is realized using our experimental setup. It is easy to couple with CMOS/SEED smart pixel arrays by using 2-D optical fiber bundle arrays as the I/O access devices. Compact in comparison with other optical interconnection systems. 相似文献
14.
We study light localization at a phase-slip defect created by two semi-infinite mismatched identical arrays of coupled optical waveguides. We demonstrate that the nonlinear defect modes possess the specific properties of both nonlinear surface modes and discrete solitons. We analyze the stability of the localized modes and their generation in both linear and nonlinear regimes. 相似文献
15.
Ye-Qi Zhang Zheng-Da Hu Jing-Bo Xu 《International Journal of Theoretical Physics》2011,50(8):2438-2445
We propose a scheme of entanglement transfer through two independent arrays of cavities coupled by optical fibers when each
of the cavities contains a single two-level atom. We study the entanglement dynamics of the transferred states and find the
explicit expression for the density matrix and concurrence. It is shown that the amount of the transferred entanglement has
a direct connection with the target states and the lengths of the arrays of cavities. Moreover, the influence of the initial
states and the length of the arrays of cavities on the phenomenon of entanglement sudden death is also investigated. 相似文献
16.
We elucidate in this Letter plasmonic Zener tunneling (PZT) in metal-dielectric waveguide arrays (MDWAs) by using numerical simulations and theoretical analyses. PZT in MDWAs occurs at the waveguide entrance and wherever the beam completes Bloch oscillations, because the bandgap between the first and second bands is minimal at the center of the first Brillouin zone. This feature significantly differs from that of optical Zener tunneling in dielectric waveguide arrays. The dependence of the simulated tunneling rate on the gradient of the relative permittivity of the dielectric layers correlates with the tunneling theory, thus confirming the occurrence of PZT in MDWAs. 相似文献
17.
Kravets VG Zoriniants G Burrows CP Schedin F Casiraghi C Klar P Geim AK Barnes WL Grigorenko AN 《Physical review letters》2010,105(24):246806
We present composite plasmonic nanostructures designed to achieve cascaded enhancement of electromagnetic fields at optical frequencies. Our structures were made with the help of electron-beam lithography and comprise a set of metallic nanodisks placed one above another. The optical properties of reproducible arrays of these structures were studied by using scanning confocal Raman spectroscopy. We show that our composite nanostructures robustly demonstrate dramatic enhancement of the Raman signals when compared to those measured from constituent elements. 相似文献
18.
Composites of resonant dielectric rods: A test of their behavior as metamaterial refractive elements
We report numerical experiments of optical wave propagation in composites of high refractive index dielectric rods at frequencies where their first electric and magnetic Mie resonances are excited. The arrays of these particles have been extensively studied and proposed as non-absorbing and isotropic metamaterials. We show that negative refraction, observed in such ordered particle arrays, is due to diffraction and that an effective medium theory (EMT) yields constitutive parameters that do not reproduce the observations in these composites, whose transmission also depends on the sample shape. This is further confirmed by disordering the arrays, a case in which large transmission losses appear due to extinction by resonant scattering from the particles. Therefore, these composites, although having little absorption, give rise to large extinction due to scattering and do not constitute an improvement, as low loss refractive elements, upon all previously designed highly absorbing metamaterials. 相似文献
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20.
Nonconservative optical forces acting on dipolar particles are considered in longitudinally invariant optical fields. We demonstrate that the orientation of these forces is strictly dictated by the propagation vector associated with such field configurations. As a direct consequence of this, it is impossible to achieve a reversal of optical forces in homogeneous media. We show instead that translation invariant optical tractor fields can in fact be generated in the negative index environment produced in a special class of fully dielectric waveguide arrays. 相似文献