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1.
A photonic crystal fibre (PCF) with zero-dispersion wavelength around 800 nm is designed and fabricated. Simulated results show that the zero-dispersion wavelength of fundamental mode for this PCF is at 826nm, and phase-matched four-wave mixing can be achieved in fundamental mode. Using 20ors Ti:sapphire laser with central wavelength at 810nm as pump, the anti-Stokes line around 610hm & generated efficiently. The output signal has a Gaussian-like profile, which indicates that the anti-Stokes signal is in the fundamental mode of the PCF. The energy of anti-Stokes signal is higher than that of residual pump laser and the maximum ratio of the anti-Stokes signal to the pump component in the output spectrum is estimated to be 1.2. 相似文献
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制备了不同单体浓度的聚合物稳定铁电液晶器件,测试了震动实验和热稳定实验前后样品的排列织构、电光特性和对比度.用原子力显微镜研究了各样品的聚合物形貌,表明在器件内部形成了沿摩擦方向延伸的聚合物网络,并且随着单体含量的增加聚合物网络更加致密.由于聚合物网络体锚定的引入,使得铁电液晶分子在外力和温度场下的运动受到限制,聚合物体锚定的增强使聚合物稳定铁电液晶的稳定性也逐渐提高.实验结果表明,单体含量为4%时,聚合物稳定铁电液晶的抗震性和热稳定性良好,电光曲线为无阈值“V”字型,对比度达150∶1. 相似文献
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The main purpose of this research is to show the effects of solvent nature, partial charge distribution and polarity index, on the preparation of uniform silane self-assembly monolayers. Octadecyltrichlorosilane (OTS) on silicon wafers was chosen as a case study. Contrary to what was thought before, dipole moment data are not enough and one needs accompanying data on partial charge distribution and polarity index to predict the best solvent for a uniform self-assembled monolayer (SAM). Results can be applied to other monolayer-solvent systems. 相似文献
4.
V.S.U. Fazio L. Komitov C. Radüge S.T. Lagerwall H. Motschmann 《The European physical journal. E, Soft matter》2001,5(3):309-315
The influence of capillary flow on the alignment of the nematic liquid crystal 5CB on fatty acid Langmuir-Blodgett monolayers
was studied by optical second-harmonic generation (SHG). The surface dipole sensitivity of the technique allows probing the
orientation of the first liquid crystal monolayer in the presence of the liquid crystal bulk. It was found that capillary
flow causes the first monolayer of liquid crystal molecules in contact with the fatty acid monolayer to be oriented in the
flow direction with a large pretilt (78 degrees), resulting in a quasi-planar alignment with splay-bend deformation of the
nematic director in the bulk. The large pretilt angle also suggests that the Langmuir-Blodgett film itself is affected by
the flow. The quasi-planar flow-induced alignment was found to be metastable. Once the flow ceases, circular domains of homeotropic
orientation nucleate in the sample and expand until the whole sample becomes homeotropic. This relaxation process from flow-induced
quasi-planar to surface-induced homeotropic alignment was also monitored by SHG. It was found that in the homeotropic state
the first nematic layer presents a pretilt of 38 degrees almost isotropically distributed in the plane of the cell, with a
slight preference for the direction of the previous flow.
Received 8 November 2000 and Received in final form 12 March 2001 相似文献
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Toshihiko Sakurai Maki Horikawa Makoto Takafuji Atsushi Kubo Hirotaka Ihara 《Applied Surface Science》2006,253(2):869-873
An l-glutamic acid-derived lipid with a terminal thiol has been synthesized and its corresponding self-assembled structure on Au(1 1 1) surfaces described. The surface morphology of the lipid self-assembled monolayer (SAM) exhibits nano-order patterning, where the height of the monolayer (approximately 1.5 nm) could be interpreted as due to the monolayer structure estimated from molecular models. The molecular orientation in the monolayer is almost perpendicular to the Au(1 1 1) surface depending on the three-point hydrogen-bonding sites in the molecule. 相似文献
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K. Kato K. Tanaka S. Kayukawa K. Suzuki Y. Masuda T. Kimura K. Nishizawa T. Miki 《Applied Physics A: Materials Science & Processing》2007,88(2):273-276
CaBi4Ti4O15 (CBTi144) micro-plateaus were fabricated on Si wafers and Pt foils using a self-assembled monolayer (SAM) and a complex metal
alkoxide solution. The micro-plateaus are delineated by metal masks, which are used for shadowing against the ultraviolet
(UV) irradiation for decomposition of SAM to make the surface hydrophilic. The micro-plateaus crystallized to a ferroelectric
phase with random orientation. The crystallization depended on the SAM-derived ultra thin layers at the surface of the substrates.
The primitive PFM measurements without any top electrodes confirmed that the micro-plateaus exhibited the piezoresponse behaviors.
The piezoelectric constant, d33, had some distribution, and the maximum d33 was confirmed as about 45 pm/V, which is identical to the d33 of the polar-axis oriented CBTi144 thin films.
PACS 77.84.-s; 81.20.Fw; 77.65.-j 相似文献
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Generation of Optical Vortex Using a Spiral Phase Plate Fabricated in Quartz by Direct Laser Writing and Inductively Coupled Plasma Etching 下载免费PDF全文
A simple, economical and reliable technique is proposed for fabricating a spiral phase plate (SPP) in a quartz substrate to generate optical vortex with a unit topological charge at the wavelengths of 632.8nm. The spiral phase plate is first formed in the photoresist by direct laser writing lithography and then transferred into the quartz substrate by inductively coupled plasma etching. The performance of the fabricated SPP is verified by using beam intensity distribution, which is in agreement with the theoretical calculation result. The interference measurement suggests that we have succeeded to generate optical vortex with a unit topological charge with the fabricated SPP. 相似文献
12.
由铁电液晶(FLC)手性近晶C相下螺旋结构的理论近似计算得出FLC一个螺距内平均折射率的表达式,根据表达式可得出一个螺距内的FLC分子作为一个整体可以看成一个向列相液晶分子模型的结论.当FLC沿螺旋轴方向的厚度等于FLC螺距的整数倍时,液晶盒内垂直取向的FLC分子可看作向列相液晶模型组成的集合.ZLI-3654型FLC与5CB型向列相液晶的实验结果验证了上述结论,理论结果和实验结果一致.这一理论可为畸变螺旋FLC和垂直排列畸变螺旋FLC器件的制备以及FLC的应用提供理论指导和更深的认识.
关键词:
铁电液晶
螺距
平均折射率
向列相液晶 相似文献
13.
Jingjing WangDa Chen Yaoguo GanXuejun Sun Yingying Jin 《Applied Surface Science》2011,257(9):4365-4369
We fabricated a self-assembled monolayer (SAM) modified solid mounted resonator (SMR) for organophosphate vapor detection. The SMR device consisted of a piezoelectric stack and an all-metal Bragg's reflector. The electrode surface is chemically modified with a Cu2+/11-mercaptoundecanoic acid SAM to capture organophosphate compounds. After chemical modification, both the resonance frequency and the Q-factor decrease. Fourier transform infrared external reflection spectroscopy was performed to verify the formation of SAM. Adsorption of organophosphate compounds onto the SAM increases its mass, and the resonance frequency proportionally goes down. The testing results show that the modified SMR can yield a rapid, sensitive, reversible and reproducible response to nerve-agent (dimethyl methyl phosphonate) vapor. This study proves that using the SAM modified SMR to detect trace organophosphate vapor is feasibility. 相似文献
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J.J. Carvajal M.C. Pujol M. Aguiló J.R. Vázquez de Aldana P. Moreno T. Trifonov R. Alcubilla J. Ferré-Borrull L.F. Marsal R. Macovez 《Journal of luminescence》2009,129(12):1441-1447
We revisited two different strategies to fabricate 1D photonic crystals of nonlinear optical dielectric materials based on ultrafast laser ablation of the surface of an RbTiOPO4 crystal, and selective etching of ferroelectric domains of the surface of a periodically poled LiNbO4 crystal. We evaluated their behaviour as Bragg diffraction gratings. We also presented the recent advances we developed in a new procedure of fabrication of 2D and 3D photonic crystals of KTiOPO4 (KTP) grown on the surface of a KTP substrate by liquid phase epitaxial means within the pores of a silicon macroporous template. Optical, structural, morphological, and compositional characterization for the photonic crystals produced through this technique are presented. 相似文献
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P. Stein N. Aßfalg H. Finkelmann P. Martinoty 《The European physical journal. E, Soft matter》2001,4(3):255-262
We investigate the behavior of the complex shear modulus of a series of elastomers including mono-domain and poly-domain liquid
crystal samples, and a non-mesomorphic sample. We find that the dynamics of the glass transition are strongly modified by
the nematic order. This result explains why the truly elastic response of liquid crystal elastomers can only be observed in
the isotropic phase at very high temperatures and at very low frequencies. Between the elastic regime and the glassy state,
the elastomers have a visco-elastic regime, which is characterized by a Rouse-like behavior for mono-domain and poly-domain
samples, and by a Zimm-like behavior for the non-mesomorphic sample. We also show that the mono-domain sample exhibits marked
anisotropy of the shear-modulus G
′. This anisotropy, which is observed for the first time, is a function of frequency and is inverted between low and high frequencies,
due to relaxation effects of the orientational order.
Received 28 January 2000 and Received in final form 16 October 2000 相似文献
16.
PREPARATION OF STRIPE-SHAPED DOMAIN STRUCTURE IN FERROELECTRIC LIQUID CRYSTAL AND THE FABRICATION OF SPATIAL LIGHT MODULATOR 下载免费PDF全文
The stripe-shaped domain (SSD) structure was prepared in the initial ferroelectric liquid crystal (FLC) alignment without the application of an external electric field, which was realized by the aligning layer modification through the doping of tin tetra-2, 4-dimethyl phenoxy phthalocyanine (SnPc) into the rubbed polyimide films. Atomic force microscopy was used to investigate the alignment films and the corresponding aligning ability was evaluated through the pre-tilt angle measurement. The memory capability and the contrast ratio of thus aligned SSFLC cells have been enhanced and improved with the appearance of the SSD structure. The electrically controlled 64×64 FLC spatial light modulator was fabricated using the improved ligning method, which proves valuable for the practical device fabrication. 相似文献
17.
To eliminate the occurrence of disclination lines in the hole patterned electrode liquid crystal microlens array (LC MLA), inserting an ultrathin dielectric slab was proved to be an effective method. The thickness of the dielectric slab played an important role in effecting the optical performance of the liquid crystal microlens array device, including the dynamic focal range, focus diameter and symmetry of phase profile. In this paper, we studied the effect of dielectric slab thickness on the optical performance of the liquid crystal microlens array by numerical simulation. It is indicated that the optical performance of the device could be improved by reducing the dielectric slab thickness, assuming that the dielectric slab thickness was larger than the threshold thickness. The dependence of the threshold thickness on some key parameters was investigated and the associated effect on the optical performance by changing these key parameters was also studied. In the end, the approaches to enhance the optical performance, namely the dynamic focal range of the liquid crystal microlens array was proposed and proved to be in effect by numerical simulation results. 相似文献
18.
The formation of molecular-scale patterns at surfaces as a self-assembled monolayer (SAM) demands adsorbate mobility, whereas devices require stability. We describe a method of photo- or electron-imprinting a SAM of CH3Br(ad) as covalently-bound Br-Si(s) at Si(1 1 1)7 × 7, with pattern-retention. This imprinting process, it is proposed, involves charge-transfer to the adsorbate, followed by downward recoil of Br− to give chemical attachment of Br at the reactive Si-atom beneath the parent physisorbed methyl bromide. The electron may subsequently be returned to the substrate along with the excess energy, accounting for the localised Br-imprint. 相似文献
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S. Nagaoka E. Okada S. Doi M. Mitsui A. Nakajima 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):239-242
V(benzene)2 sandwich cluster cations produced in the gas phase
were size-selectively deposited onto a self-assembled monolayer of
n-hexadecanethiols (HDT-SAM) chemisorbed on a Au(111) surface as well as onto
a bare Au(111) surface. The thermal chemistry of the neutralized clusters on
each substrate was studied with temperature programmed desorption (TPD).
From the analyses of the threshold in the TPD, the desorption
activation energies of the clusters deposited were determined to be 64.4
±12.8 kJ/mol for the Au(111) and 130 ±10 kJ/mol for the HDT-SAM.
The remarkably large desorption activation energy from the SAM suggests that
the deposited clusters are incorporated into the SAM matrix and
firmly trapped inside the alkyl chains of the SAM. 相似文献