Terahertz active photonic crystals for condensed gas sensing

The terahertz (THz) spectral region, covering frequencies from 1 to 10 THz, is highly interesting for chemical sensing. The energy of rotational and vibrational transitions of molecules lies within this frequency range. Therefore, chemical fingerprints can be derived, allowing for a simple detection...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2011-06, Vol.11 (6), p.6003-6014
Main Authors: Benz, Alexander, Deutsch, Christoph, Brandstetter, Martin, Andrews, Aaron M, Klang, Pavel, Detz, Hermann, Schrenk, Werner, Strasser, Gottfried, Unterrainer, Karl
Format: Article
Language:English
Subjects:
active resonator
Algorithms
Argon - chemistry
Biosensing Techniques
Equipment Design
Gases - analysis
Lasers
Optical Devices
optical microsensor
Oxygen - chemistry
Photons
Quantum dots
Quantum Theory
quantum-cascade laser
Radiation
Refractometry
Reproducibility of Results
Sensors
terahertz
Terahertz Radiation
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Summary:The terahertz (THz) spectral region, covering frequencies from 1 to 10 THz, is highly interesting for chemical sensing. The energy of rotational and vibrational transitions of molecules lies within this frequency range. Therefore, chemical fingerprints can be derived, allowing for a simple detection scheme. Here, we present an optical sensor based on active photonic crystals (PhCs), i.e., the pillars are fabricated directly from an active THz quantum-cascade laser medium. The individual pillars are pumped electrically leading to laser emission at cryogenic temperatures. There is no need to couple light into the resonant structure because the PhC itself is used as the light source. An injected gas changes the resonance condition of the PhC and thereby the laser emission frequency. We achieve an experimental frequency shift of 10(-3) times the center lasing frequency. The minimum detectable refractive index change is 1.6 × 10(-5) RIU.
ISSN:1424-8220
1424-8220
DOI:10.3390/s110606003