F-Products and Nonstandard Hulls for Strongly Continuous One-parameter Semigroups of Linear Operators

We give an overview of the F-product construction and the corresponding nonstandard constructions for strongly continuous one-parameter semigroups of linear operators, and show that (in the case of bounded ultrapowers) both constructs are isomorphic. From this we also deduce a "classical" corollary about the nonexistace of certain semigroups.Comment: 13 page

Pyroelectric activity of ferroelectric PT/PVDF-TRFE

Author name used in this publication: F. G. ShinAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: C. L. Choy2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Separate poling of inclusions and matrix in PT/P(VDF-TrFE) 0-3 composites

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Generation and subwavelength focusing of longitudinal magnetic fields in a metallized fiber tip

We demonstrate experimentally and numerically that in fiber tips as they are used in NSOMs azimuthally polarized electrical fields (|E$_{\text{azi}}$|$^2$/|E$_{\text{tot}}$|$^2$ $\approx$ 55% $\pm$ 5% for 1.4\mu m tip aperture diameter and \lambda$_0$ = 1550nm), respectively subwavelength confined (FWHM $\approx$ 450nm $\approx$ \lambda$_0$/3.5) magnetic fields, are generated for a certain tip aperture diameter (d = 1.4\mu m). We attribute the generation of this field distribution in metal-coated fiber tips to symmetry breaking in the bend and subsequent plasmonic mode filtering in the truncated conical taper.Comment: 11 pages, 6 figure

Internal fields in PT/PVDF-TrFE 0-3 composites

Author name used in this publication: F. G. ShinRefereed conference paper2000-2001 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Pyroelectric or piezoelectric compensated ferroelectric composites

Author name used in this publication: F. G. ShinAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: C. L. ChoyVersion of RecordPublishe

Polarization features of optically pumped CdS nanowire lasers

High quality CdS nanowires suspended in air were optically pumped both below and above the lasing threshold. The polarization of the pump laser was varied while emission out of the end facet of the nanowire was monitored in a 'head-on' measurement geometry. Highest pump-efficiency and most efficient absorption of the pump radiation are demonstrated for an incident electric field being polarized parallel to the nanowire axis. This polarization dependence, which was observed both above the lasing threshold and in the regime of amplified spontaneous emission, is caused by an enhanced absorption for parallel polarized optical pumping. Measured Stokes parameters of the nanowire emission reveal that due to the onset of lasing the degree of polarization rapidly increases from approximately 15% to 85%. Both, Stokes parameters and degree of polarization of the nanowire lasing emission are independent of the excitation polarization. The transversal lasing mode is therefore not notably affected by the polarization of the pumping beam, although the supply with optical gain is significantly enhanced for an excitation polarization parallel to the nanowire axis

Young's Double-Slit, Invisible Objects and the Role of Noise in an Optical Epsilon-near-Zero Experiment

Epsilon-near-zero (ENZ) media disclose the peculiarities of electrodynamics in the limit of infinite wavelength but non-zero frequency for experiments and applications. Theory suggests that wave interaction with obstacles and disturbances dramatically changes in this domain. To investigate the optics of those effects we fabricated a nanostructured 2D optical ENZ multilayer waveguide that is probed with wavelength-tuned laser light via a nanoscale wave launch configuration. In this experimental framework we directly optically measure wave propagation and diffraction in a realistic system with the level and scale of imperfection that is typical in nanooptics. As we scan the wavelength from 1.0 $\mu$m to 1.7 $\mu$m, we approach the ENZ regime, and observe the interference pattern of a micro-scale Young's double slit to steeply diverge. By evaluating multiple diffraction orders we experimentally determine the effective refractive index $n_{eff}$ and its zero-crossing as an intrinsic measured reference, which is in agreement with theoretical predictions. We further verify that the double-slit and specifically placed scattering objects become gradually invisible when approaching the ENZ regime. We also observe that light-matter-interaction intensifies towards ENZ and quantify how speckle noise, caused by tiny random imperfections, increasingly dominates the optical response and blue-shifts the cut-off frequency.Comment: 24 pages manuscript with 4 figures and 40 pages supplementary information with 27 figure

Poling of ferroelectric composites

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Influence of electric potential on the apparent viscosity of an ionic liquid: facts and artifacts

A study on the electro-rheology of an ionic liquid that identifies and explains the occurrence of measurement artifacts in cone-on-plate viscometry.</p