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Mid-infrared silicon photonics for sensing applications

Published online by Cambridge University Press:  28 May 2012

Goran Z. Mashanovich ,
Milan M. Milosevic ,
Milos Nedeljkovic ,
David Cox ,
Vittorio M. N. Passaro ,
Harold M. H. Chong  and
Richard Soref
Goran Z. Mashanovich
Affiliation:
School of Electronics and Computer Science, University of Southampton, Southampton, UK*
Milan M. Milosevic
Affiliation:
Advanced Technology Institute, University of Surrey, Guildford, Surrey, UK
Milos Nedeljkovic
Affiliation:
School of Electronics and Computer Science, University of Southampton, Southampton, UK*
David Cox
Affiliation:
Advanced Technology Institute, University of Surrey, Guildford, Surrey, UK
Vittorio M. N. Passaro
Affiliation:
Dipartimento di Elettrotecnica ed Elettronica, Politecnico di Bari, 70125 Bari, Italy
Harold M. H. Chong
Affiliation:
School of Electronics and Computer Science, University of Southampton, Southampton, UK*
Richard Soref
Affiliation:
Physics and Engineering Departments, University of Massachusetts at Boston, Boston, MA 02125 USA
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Abstract

The mid-infrared wavelength region offers a plethora of possible applications ranging from sensing, medical diagnostics and free space communications, to thermal imaging and IR countermeasures. Hence group IV mid-infrared photonics is attracting more research interest lately. Sensing is an especially attractive area as fundamental vibrations of many important gases are found in the 3 to 14 μm spectral region. To realise group IV photonic mid-infrared sensors several serious challenges need to be overcome. The first challenge is to find suitable material platforms for the mid-infrared. In this paper we present experimental results for passive mid-infrared photonic devices realised in silicon-on-insulator (SOI), silicon-on-sapphire (SOS), and silicon on porous silicon (SiPSi). Although silicon dioxide is lossy in most parts of the mid-infrared, we have shown that it has potential to be used in the 3-4 μm region. We have characterized SOI waveguides with < 1 dB/cm propagation loss. We have also designed and fabricated SOI passive devices such as MMIs and ring resonators. For longer wavelengths SOS or SiPSi structures could be used. An important active device for long wavelength group IV photonics will be an optical modulator. We present relationships for the free-carrier induced electro-refraction and electro-absorption in silicon in the mid-infrared wavelength range. Electro-absorption modulation is calculated from impurity-doping spectra taken from the literature, and a Kramers-Kronig analysis of these spectra is used to predict electro-refraction modulation. We have examined the wavelength dependence of electro-refraction and electro-absorption, and found that the predictions suggest longer-wave modulator designs will in many cases be different than those used in the telecom range.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1437: Symposium L – Group IV Photonics for Sensing and Imaging , 2012 , mrss12-1437-l02-03
Copyright
Copyright © Materials Research Society 2012

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References

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