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Your search keyword '"Edwardson, S. P."' showing total 5 results
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5 results on '"Edwardson, S. P."'

1. NUV femtosecond laser inscription of volume Bragg gratings in poly (methyl) methacrylate with linear and circular polarizations

Author

Ye, L, Perrie, Walter, Allegre, Olivier, Jin, Y, Kuang, Z., Scully, Patricia, Fearon, E, Eckford, D, Edwardson, S P, and Dearden, Geoff

Abstract

Large, high efficiency, volume Bragg gratings with dimensions of 5 mm× 5 mm and thickness between 1 and 7 mm with 20 μm pitch have been inscribed in poly (methyl) methacrylate (PMMA) with 180 fs, 387 nm parallel beams using both linear and circular polarizations. Linear polarization (perpendicular to the scan direction) produced the highest refractive index contrast, while circular polarization produced the lowest. The measured first-order diffraction efficiency with grating thickness L agrees well with theoretical expectations, and reached a maximum of 94% near L= 4 mm, the highest yet observed in pure PMMA. The source of the variation in refractive index contrast was investigated, and it was found to be due to the polarization-dependent nonlinear filamentation, the first such observation in a pure polymer.

Published
2013
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5. Multiple Beam Internal Structuring of Poly(methyl methacrylate).

Author

Dun LIU, PERRIE, Walter, Zheng KUANG, SCULLY, P. J., BAUM, A., LIANG, S., TARANU, A., EDWARDSON, S. P., FEARON, E., DEARDEN, G., and WATKINS, K. G

Subjects
SPATIAL light modulators, OPTICAL modulators, FEMTOSECOND lasers, METHYL methacrylate, INDUSTRIAL lasers, NANOMECHANICS, LASER microscopy, NANOTECHNOLOGY
Abstract

Spatial light modulator addressed with computer generated holograms is used to diffract femtosecond laser pulses into > 15 parallel beams and focused simultaneously inside poly(methyl methacrylate) (PMMA) for high throughput 3D refractive index modification. Uniform modification throughout the structure is demonstrated and used to create a 19 μm pitch, 5 × 5 × 3.5 mm³ thick volume grating in < 50 minutes with first order Bragg diffraction efficiency > 65%. Thick volume phase gratings are created by carefully stitching filamentary modifications. PMMA shows a remarkable time dependent Δn, related to the photochemistry during and after exposure. [ABSTRACT FROM AUTHOR]

Published
2012
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