E5.3 - Photonic Microstructures for Gas Detection in the MIR
- AMA Conferences 2015
2015-05-19 - 2015-05-21
- Proceedings SENSOR 2015
- E5 - Gas Sensors I
- C. Kraeh, A. Popescu - Siemens AG, München (Germany), J. Martinez-Hurtado, J. Finley - Technische Universität München, Garching (Germany)
- 668 - 673
This paper reports on the fabrication and the investigation of photonic microstructures, which are capable of enhancing the sensitivity of spectroscopic gas sensors in the mid-infrared spectral region, and thus provides routes towards fully integrated and miniaturized on-chip solutions. The presented photonic crystal structures consist of high aspect ratio microtube arrays. The microtubes are produced by etching an array of macropores into a silicon substrate using a photoassisted electrochemical etching technique, subsequently filling these pores via chemical vapor deposition and removing the silicon substrate via anisotropic etching. These photonic crystal structures are optimized for strong transmittance in the mid-infrared from 5-8 μm, whereas a major part of the electromagnetic density propagates in-between the microtubes, where it can be absorbed by gas molecules. By using slow light effects, i.e. reduced group velocities of the propagating light, absorption by gas molecules was enhanced by roughly a factor of 10 inside the photonic crystal.