Details

Autor(en) / Beteiligte

• Cardador, D.
• Vega, D.
• Segura, D.
• Trifonov, T.
• Rodríguez, A.

Titel

Enhanced geometries of macroporous silicon photonic crystals for optical gas sensing applications

Ist Teil von

• Photonics and nanostructures, 2017-07, Vol.25, p.46-51

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• •3-d Photonic Crystals based on macroporous silicon with a cavity inserted in the middle of the structure have been explored to find an optimum Q-factor of their transmission peak.•It is demonstrated both theoretically and experimentally an increasing of almost an order of magnitude in the Q-factor of the transmitted peaks.•Its response to CO2 has been simulated and has been found that for the optimized PhC structure, a large variation of 70% in transmitted peak amplitude can be obtained with a sensitivity of 0.8%/c%.•The conclusion driven is that such PhCs are suitable for the detection of strong absorbing gases by non-dispersive infrared spectroscopy. A macroporous silicon photonic crystal is designed and optimized theoretically for its use in gas sensing applications and IR optical filters. Light impinges perpendicularly onto the sample surface (vertical propagation) so a three-dimensional (3d) structure is used. For gas sensing, a sharp resonance is desired in order to isolate an absorption line of the gas of interest. The high Q-factors needed mandate the use of a plane defect inside the PhC to give rise to a resonant mode inside the bandgap tuned to the gas absorption line. Furthermore to allow gas passage through the device, an open membrane is required. This can affect the mechanical resilience. To improve the strength of the photonic crystal the pores are extended after the “active” 3d part. The number of modulations, and the extension length have been optimized to obtain the largest Q-factor with reasonable transmitted power. These proposed structures have been experimentally performed, probing an enhancement of almost an order of magnitude in the Q-factor in respect with the basic case. Simulations considering CO2 have been performed showing that the proposed structures are promising as precise optical gas sensors.