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Proceedings Paper

Holographic recording of sub-micron period gratings and photonic crystals in the photoresist SU8
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Paper Abstract

SU8 is a commercial negative photoresist, which is highly transparent in the visible and near-infrared and extremely resistant to many organic solvents. Here we show that sub-micron period diffraction gratings, and 2D photonic crystal structures, can be readily formed holographically over extended areas. By coating the SU8 layer with a suitable gain medium, such structures may be used as feedback and output-coupling gratings for organic waveguide lasers. Thin films of SU8, were initially deposited by spin casting onto glass substrates. These films were then mounted in one arm of a Lloyd's mirror interferometer and exposed with the expanded beam of a HeCd laser, operating at 325 nm. Subsequent baking and developing steps lead to both volume gratings with index contrast of 0.014, and surface gratings with corrugation depths of up to 140 nm. By varying the incidence angle of the HeCd laser beam to the SU8 film we have tuned the microstructure period from 500 nm down to 200 nm. Using multiple exposures, both doubly-periodic diffraction gratings and square-lattice crystal structures have been produced.

Paper Details

Date Published: 27 August 2005
PDF: 7 pages
Proc. SPIE 5931, Nanoengineering: Fabrication, Properties, Optics, and Devices II, 59311B (27 August 2005); doi: 10.1117/12.616718
Show Author Affiliations
Fiona M. Bain, Univ. of St. Andrews (United Kingdom)
Andreas E. Vasdekis, Univ. of St. Andrews (United Kingdom)
Graham A. Turnbull, Univ. of St. Andrews (United Kingdom)

Published in SPIE Proceedings Vol. 5931:
Nanoengineering: Fabrication, Properties, Optics, and Devices II
Elizabeth A. Dobisz; Louay A. Eldada, Editor(s)

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