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I C Khoo

Publications and source records attributed to I C Khoo.

5 recordsLinked to original sources
PubMed2006

Nanosphere dispersed liquid crystals for tunable negative-zero-positive index of refraction in the optical and terahertz regimes.

An analysis of aligned nematic liquid crystal cells containing core-shell nanospheres shows that it is possible to devise a new type of metamaterial whose index of refraction is tunable from negative, through zero, to positive values. The design parameters for the constituents can be scaled for application in the optical as well as very long wavelength (e.g., terahertz and microwave) regions.

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PubMed2004

Finite-size effect on one-dimensional coupled-resonator optical waveguides.

We study the finite-size effect on the dispersion relation, group velocity, and transmission curves of one-dimensional finite-size coupled-resonator optical waveguide (CROW) structures. Both the dispersion relation and the group velocity curves of a finite-size CROW oscillate along those of the corresponding infinite-extended ones. The oscillations can be suppressed by matching the equivalent admittance of the surrounding medium to that of the unit cell. Thelen's method is used to find the parameters of the matching layer to reduce oscillations on the group velocity and transmission spectra, and to analyze the structure parameters that determine the bandwidth and the group velocity.

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PubMed2003

All-optical neural-net-like image processing with photosensitive nonlinear nematic film.

Received June 30, 2003 We demonstrate that some neural-net image-processing operations can be realized in an all-optical manner by use of the natural diffraction property of light in conjunction with the photosensitivity and optical nonlinearities of a transparent thin film. An example of image edge enhancement is illustrated with photosensitive supranonlinear nematic liquid-crystal films.

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PubMed2003

Nonlinear dynamics in laser polarization conversion by stimulated scattering in nematic liquid crystal films.

We present a study of the nonlinear dynamics of a coherent polarization conversion process in nematic liquid crystal films. This effect is mediated by two-beam coupling between the incident polarized laser and its orthogonally polarized (lower-frequency) noise component scattered by the director axis fluctuations. A complete model for the director dynamics derived from the basic equations is presented. The existence of complex, time-, and intensity-dependent dynamics of the director motion such as oscillations and various bifurcations including period doubling is revealed.

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