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Miniature infrared gas sensors using photonic crystals

 
: Pergande, D.; Geppert, T.; Rhein, A. von; Schweizer, S.; Wehrspohn, R.; Moretton, S.; Lambrecht, A.

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Postprint urn:nbn:de:0011-n-1610454 (4.3 MByte PDF)
MD5 Fingerprint: 04614cb70f1189be3ffa17333764dd6f
Erstellt am: 23.5.2014


Journal of applied physics 109 (2011), Nr.8, Art. 083117, 7 S.
ISSN: 0021-8979
ISSN: 1089-7550
Englisch
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer IWM ()
Fraunhofer IPM ()
optical gas sensor; photonic crystal; infrared

Abstract
We present an optical gas sensor based on the classical nondispersive infrared technique using ultracompact photonic crystal gas cells. The ultracompact device is conceptually based on low group velocities inside a photonic crystal gas cell and low-reflectivity antireflection layers coupling light into the device. Experimentally, an enhancement of the CO2 infrared absorption by a factor of 2.6 to 3.5 as compared to an empty cell, due to slow light inside a 2D silicon photonic crystal gas cell, was observed; this is in excellent agreement with numerical simulations. We show that, theoretically, for an optimal design enhancement factors of up to 60 are possible in the region of slow light. However, the overall transmission of bulk photonic crystals, and thus the performance of the device, i s limited by fluctuations of the pore diameter. Numerical estimates suggest that the positional variations and pore diameter fluctuations have to be well below 0.5% to allow for a reasonable transmission of a 1 mm device.

: http://publica.fraunhofer.de/dokumente/N-161045.html