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Proceedings Paper

Optical and mechanical design of an InP-based tunable detector for gas-sensing applications
Author(s): Paolo Bondavalli; Taha Benyattou; Michel Garrigues; Jean Louis Leclercq; Philippe Regreny; K. Sun; Pierre Viktorovitch; Sebastein Cortial; Xavier Hugon; Christophe Pautet
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Paper Abstract

It has been shown that it is possible to produce highly selective and continuously tunable filters based on InP material using surface micro-machining. One interesting issue for this kind of device is NIR absorption spectroscopy for gas analysis. In this work, we present the design of a Resonant Cavity Enhanced tunable photodiode for operation around 1.6 micrometer near the C-H stretching frequency for organic molecules such as benzene. For this type of application, the required performances are a large tunability, a high selectivity, a weak temperature dependence and a constant absorption level over the tuning range. To meet these requirements the micro-system must be optimized from the optical and mechanical point of view. The RCE photodiode structure is composed of an air/InP bottom Bragg mirror and a dielectric top Bragg mirror. The cavity includes an air-gap and the InP layer containing a p.i.n. photodiode with absorption in a few strained InGaAs Quantum Wells (QWs). Tuning is obtained by actuating electrostatically the air micro-cavity thickness. A prospective device meeting the optical requirements has been designed. It is based on an absorption region composed of three InGaAS QWs conveniently located in the cavity standing wave pattern in order to optimize the resonant absorption over the tuning range. Optical simulation shows that an absorption level greater than 50% can be achieved. The temperature dependence of the resonance wavelength can be kept below 0.08 nm/(Delta) T(C degrees) at room temperature. The mechanical properties of the micromachined structure has been investigated using finite element analysis.

Paper Details

Date Published: 2 September 1999
PDF: 11 pages
Proc. SPIE 3878, Miniaturized Systems with Micro-Optics and MEMS, (2 September 1999); doi: 10.1117/12.361259
Show Author Affiliations
Paolo Bondavalli, Institut National des Sciences Appliquees de Lyon (France)
Taha Benyattou, Institut National des Sciences Appliquees de Lyon (France)
Michel Garrigues, Ecole Centrale de Lyon (France)
Jean Louis Leclercq, Ecole Centrale de Lyon (France)
Philippe Regreny, Ecole Centrale de Lyon (France)
K. Sun, Ecole Centrale de Lyon (France)
Pierre Viktorovitch, Ecole Centrale de Lyon (France)
Sebastein Cortial, Thomson-CSF (France)
Xavier Hugon, Thomson-CSF (France)
Christophe Pautet, Thomson-CSF (France)


Published in SPIE Proceedings Vol. 3878:
Miniaturized Systems with Micro-Optics and MEMS
M. Edward Motamedi; Rolf Goering, Editor(s)

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