Optical-feedback cavity-enhanced absorption spectroscopy with a quantum cascade laser
Optical-feedback cavity-enhanced absorption spectroscopy is demonstrated in the mid-IR by using a quantum cascade laser (emitting at 4.46 μm). The laser linewidth reduction and frequency locking by selective optical feedback from the resonant cavity field turns out to be particularly advantageous in...
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| Published in | Optics letters Vol. 35; no. 21; p. 3607 |
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| Main Authors | , , , |
| Format | Journal Article |
| Language | English |
| Published |
United States
01.11.2010
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| Online Access | Get more information |
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| Summary: | Optical-feedback cavity-enhanced absorption spectroscopy is demonstrated in the mid-IR by using a quantum cascade laser (emitting at 4.46 μm). The laser linewidth reduction and frequency locking by selective optical feedback from the resonant cavity field turns out to be particularly advantageous in this spectral range: It allows strong cavity transmission, which compensates for low light sensitivity, especially when using room-temperature detectors. We obtain a noise equivalent absorption coefficient of 3 × 10(-9)/cm for 1 s averaging of spectra composed by 100 independent points. At 4.46 μm, this yields a detection limit of 35 parts in 10(12) by volume for N(2)O at 50 mbar, corresponding to 4 × 10(7) molecules/cm(3), or still to 1 fmol in the sample volume. |
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| ISSN: | 1539-4794 |
| DOI: | 10.1364/OL.35.003607 |