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Open Access Nano Express

Multilayer porous silicon diffraction gratings operating in the infrared

Meifang Lai13, Gayathri M Sridharan2, Giacinta Parish3, Shanti Bhattacharya2 and Adrian Keating1*

Author Affiliations

1 School of Mechanical and Chemical Engineering, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia, 6009, Australia

2 Department of Electrical Engineering, IIT Madras, Chennai, 600036, India

3 School of Electrical, Electronic and Computer Engineering, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia, 6009, Australia

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Nanoscale Research Letters 2012, 7:645  doi:10.1186/1556-276X-7-645

Published: 24 November 2012

Abstract

Transmission diffraction gratings operating at 1,565 nm based on multilayer porous silicon films are modeled, fabricated, and tested. Features down to 2 μm have been patterned into submicron-thick mesoporous films using standard photolithographic and dry etching techniques. After patterning of the top porous film, a second anodization can be performed, allowing an under-layer of highly uniform porosity and thickness to be achieved. High transmission greater than 40% is measured, and modeling results suggest that a change in diffraction efficiency of 1 dB for a 1% change in normalized refractive index can be achieved. Preliminary measurement of solvent vapor shows a large signal change from the grating sensor in agreement with models.

Keywords:
Porous silicon; Diffraction grating; Diffraction efficiency; Photolithography; Etching; Infrared; Sensor