Open AccessCompact gas cell integrated with a linear variable optical filter
Author(s) -
N. Pelin Ayerden,
G. de Graaf,
R.F. Wolffenbuttel
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.002981
Subject(s) - resonator , optics , materials science , miniaturization , microelectromechanical systems , microfabrication , optical cavity , absorption (acoustics) , optoelectronics , fabrication , physics , laser , nanotechnology , medicine , alternative medicine , pathology
A miniaturized methane (CH(4)) sensor based on nondispersive infrared absorption is realized in MEMS technology. A high level of functional integration is achieved by using the resonance cavity of a linear variable optical filter (LVOF) also as a gas absorption cell. For effective detection of methane at λ = 3.39 µm, an absorption path length of at least 5 mm is required. Miniaturization therefore necessitates the use of highly reflective mirrors and operation at the 15th-order mode with a resonator cavity length of 25.4 µm. The conventional description of the LVOF in terms of the Fabry-Perot resonator is inadequate for analyzing the optical performance at such demanding boundary conditions. We demonstrate that an approach employing the Fizeau resonator is more appropriate. Furthermore, the design and fabrication in a CMOS-compatible microfabrication technology are described and operation as a methane sensor is demonstrated.