Leaky-wave exploration of two-stage switch-on in a nematic pi-cell

Copyright © 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 86 (2005) and may be found at http://link.aip.org/link/?APPLAB/86/052502/1The two-stage switch-on dynamics of a nematic pi-cell are explored in detail using a convergent beam fully-leaky guided mode technique. The cell shows an initial switch-on with a time scale in the range several ms to tens of ms (depending on drive voltage) from the symmetrical H state to a new and semistable H state. It then slowly changes (over several hundred ms) to the final stable asymmetrical H state

Microwave liquid-crystal variable phase grating

Copyright © 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 85 (2004) and may be found at http://link.aip.org/link/?APPLAB/85/2041/1A voltage-controlled variable phase grating, at microwave frequencies, is described and its response characterized. It comprises a stack of 71 aluminium strips of 1 mm thickness separated by 75 µm spaces, filled with aligned nematic liquid crystal. For microwaves polarized normal to the grating strips there are a set of resonant transmitted frequencies. By varying the voltages applied across the liquid crystal layers and their distribution, a variable phase microwave grating is realized. This allows low-voltage control of output beam profile and intensity

Differential ellipsometric surface plasmon resonance sensors with liquid crystal polarization modulators

Copyright © 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 85 (2004) and may be found at http://link.aip.org/link/?APPLAB/85/3017/1Differential ellipsometric interrogation of surface plasmon (SP) resonances is a technique that gives ultrahigh sensitivity to refractive index changes, and it may provide the basis for chemical and biological sensors. In this study, a liquid crystal polarization modulator has been developed to provide such a differential technique. A refractive index sensitivity of 2×10–7 refractive index units is demonstrated, which is at least as sensitive as more established SP sensing techniques. The use of a liquid crystal modulator allows for low-voltage signal modulation and also feedback locking to zero. Possibly more important, it leads to pixelization for array sensing and for potential imaging

Dispersion of surface plasmon polaritons on short-pitch metal gratings

Ian R. Hooper and J. Roy Sambles, Physical Review B, Vol. 65, article 165432 (2002). "Copyright © 2002 by the American Physical Society."The dispersion of surface plasmon polaritons (SPPs) has been calculated for short-pitch metal gratings for various depths. For gratings with depths greater than their pitch very flat SPP bands are formed in the zero-order region of the spectrum which may be resonantly excited with radiation polarized with its electric field in the plane of incidence of the radiation, which also contains the grating vector. The dispersion curves of these modes evolve as deformations of the familiar shallow grating dispersion curve due to the opening of very large band gaps, and interactions of the SPP bands with both the light line and other SPP bands. Also presented are the dispersion curves for the equivalent modes excited by radiation having its plane of incidence perpendicular to the grating vector, but polarized with its electric field parallel to this grating vector. The full dispersion curve of these SPP bands for all orientations of the grating relative to the plane of incidence is also presented

Slow waves caused by cuts perpendicular to a single subwavelength slit in metal

Copyright © 2007 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is the published version of an article published in New Journal of Physics Vol. 9, article 1. DOI: 10.1088/1367-2630/9/1/001Resonant transmission of microwaves through a subwavelength slit in a thick metal plate, into which subwavelength cuts have been made, is explored. Two orientations of the cuts, parallel and perpendicular to the long axis of the slit, are examined. The results show that the slits act as though filled with a medium with anisotropic effective relative permeability which at low mode numbers has the two values ~(1, 9.1), increasing to ~(1, 14.4) for higher mode numbers

Coupled surface plasmon polaritons on thin metal slabs corrugated on both surfaces

Ian R. Hooper and J. Roy Sambles, Physical Review B, Vol. 70, article 045421 (2004). "Copyright © 2004 by the American Physical Society."A modelling study of the effect of coupled surface plasmon polaritons (SPPs) on the optical response of a thin metal film corrugated on both surfaces is presented. Initially the case of conformally corrugated metal films (the corrugations on each surface are identical and in phase with each other) is considered. Sinusoidal structures, and those having an additional first harmonic, 2kg (where kg is the grating vector) component, are investigated. This 2kg component opens up significant band gaps in the SPP dispersion curves, and also causes anticrossing behavior between the long range SPPs and short range SPPs. It is shown that this anticrossing, and the band gap, have a common explanation. Following this, nonconformally corrugated films are examined, and strongly enhanced resonant transmission is shown to occur, which can be almost independent of the in-plane wave vector. The results presented show that, though the enhanced transmission through hole arrays which has provoked extensive recent investigation is of great interest from a physics viewpoint, other structures which exhibit enhanced transmission may provide more benefits, including higher transmission, for some applications

Reply to “Comment on ‘Optical determination of flexoelectric coefficients and surface polarization in a hybrid aligned nematic cell’ ”

A. Mazzulla, F. Ciuchi, and J. Roy Sambles, Physical Review E, Vol. 68, article 023702 (2003). "Copyright © 2003 by the American Physical Society."In their Comment [G. Barbero and L. R. Evangelista, Phys. Rev. E 68, 023701] on our paper [A. Mazzulla, F. Ciuchi, and J. R. Sambles, Phys. Rev. E 64, 021708 (2001)], Barbero and Evangelista conclude that the procedure followed by us to fit the reflectivity data from the half leaky guided mode technique is questionable. In the absence of a model that is able to reproduce the experimentally obtained tilt angle profiles, their argument is unsubstantiated. To further refute their arguments, we also illustrate and discuss additional experimental data (that were not shown in our paper) that strongly support our conclusions

Exploration of the surface director profile in a liquid crystal cell using coupling between the surface plasmon and half-leaky optical guided modes

Copyright © 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 92 (2008) and may be found at http://link.aip.org/link/?APPLAB/92/151103/1The half-leaky guided mode geometry with a thin metal tunnel barrier as one cladding layer is used to explore the distribution of the director very near to the surface in a hybrid aligning nematic liquid crystal cell. From theoretical analysis together with numerical modeling, it is shown how the coupled p-polarized surface plasmon/s-like guided modes excited in the geometry leads to extremely sensitive to the surface director tilt profile near the metal wall—a sensitivity which is even higher than that of the surface plasmon resonance alone. The experimental results have fully confirmed the model predictions

Electromagnetic Properties of Ultrathin Quadrifilar Spirals and Their Complementary Structures

Published

Microwave surface-plasmon-like modes on thin metamaterials

Matthew J. Lockyear, Alastair P. Hibbins, and J. Roy Sambles, Physical Review Letters, Vol. 102, article 073901 (2009). Copyright © 2009 by the American Physical Society.It has recently been shown that the structured surface of a perfect conductor can support surface-plasmon-like modes [Pendry et al., Science 305, 847 (2004)]. Such structures have a thickness of at least the order of the wavelength. Here, using microwave wavelength radiation incident beyond the critical angle of a wax prism, we quantify the surface-plasmon-like dispersion for a metamaterial surface with a thickness very much smaller than the incident wavelength