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Proceedings Paper

FTIR and Raman investigation of vertically etched silicon as a 1D photonic crystal
Author(s): Vladimir A. Tolmachev; Tatiana S. Perova; Jagdish K. Vij; Ekaterina V. Astrova; Kevin Berwick; Alan Moore
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Paper Abstract

The reflection spectra of composite materials on the base of grooved silicon and grooved silicon infiltrated with nematic liquid crystal (LC) have been calculated using the optimal parameters of a grooved silicon matrix suitable for the infrared range. The grooved silicon structures with different lattice constants (A=16, 12, 8 and 4 mm) have been designed and prepared. An important parameter of these structures is the thickness of the silicon walls (DSi). This has been obtained using simulations of the spectra. This parameter was used for further analysis of the spectra of composite material grooved Si-LC. The experimental reflection is reaching of 65% in maximum (with signal modulation from maximum to minimum up to 55%) for the composite structures with a small number of lattice periods that makes these structures very perspective with a potential applications. The analysis of the polarised infrared spectra of Si structures infiltrated with LC allows one to determine the orientation and the refractive index (NLC) of the liquid crystal. For the samples with a distance between Si walls of 6-10 mm, it was found that the refractive index was NLC=~ 1.5 for polarised light and NLC 1.5 for s-polarised light. This leads to the conclusion on the planar orientation of liquid crystal molecules with respect to the Si walls. For the samples with distance between Si walls less than 3 mm, a homeotropic alignment of liquid crystal molecules has been found. Micro-Raman spectroscopy has been applied for analysis of stress in such Si structures. The maximum stress of about 2 GPa was obtained on the top of Si walls (under Si dioxide layer).

Paper Details

Date Published: 27 August 2003
PDF: 10 pages
Proc. SPIE 4876, Opto-Ireland 2002: Optics and Photonics Technologies and Applications, (27 August 2003); doi: 10.1117/12.463954
Show Author Affiliations
Vladimir A. Tolmachev, A.F. Ioffe Physico-Technical Institute (Russia)
Tatiana S. Perova, Trinity College Dublin (Ireland)
Jagdish K. Vij, Trinity College Dublin (Ireland)
Ekaterina V. Astrova, A.F. Ioffe Physico-Technical Institute (Russia)
Kevin Berwick, Dublin Institute of Technology (Ireland)
Alan Moore, Trinity College Dublin (Ireland)

Published in SPIE Proceedings Vol. 4876:
Opto-Ireland 2002: Optics and Photonics Technologies and Applications
Vincent Toal; Norman Douglas McMillan; Gerard M. O'Connor; Eon O'Mongain; Austin F. Duke; John F. Donegan; James A. McLaughlin; Brian D. MacCraith; Werner J. Blau, Editor(s)

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