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Real-time spectroscopy enabled by external cavity QCLs with MOEMS diffraction gratings

: Butschek, Lorenz; Hugger, Stefan; Jarvis, Jan-Philip; Härtelt, Marko; Merten, André; Grahmann, Jan; Boskovic, Dusan; Fuchs, Frank; Ostendorf, Ralf; Schilling, Christian; Rattunde, Marcel; Wagner, Joachim


Razeghi, M. (Ed.) ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Quantum Sensing and Nano Electronics and Photonics XIV : San Francisco, California, United States, January 28, 2017
Bellingham, WA: SPIE, 2017 (Proceedings of SPIE 10111)
ISBN: 978-1-5106-0663-0
ISBN: 978-1-5106-0664-7
Paper 101112G, 11 S.
Conference "Quantum Sensing and Nano Electronics and Photonics" <14, 2017, San Francisco/Calif.>
Fraunhofer IAF ()
Fraunhofer IPMS ()
Fraunhofer ICT ()
quantum cascade lasers; MOEMS; external cavity laser; mid-IR spectroscopy; real-time spectroscopy; Key Publication

In this contribution, we report on real-time mid-IR spectroscopy enabled by rapidly tunable External Cavity Quantum Cascade Lasers (EC-QCLs). High speed spectral scanning in a Littrow-type resonator is realized by employing a resonantly driven micro-opto-electro-mechanical-systems (MOEMS) grating as wavelength selective element. Oscillating at a frequency of 1 kHz with mechanical amplitudes of up to 10°, the MOEMS grating is able to cover the whole spectral range provided even by broad-gain QCL chips in just 500 μs. In addition to the high spectral scanning frequency, the MOEMS approach also allows for a miniaturized and rugged design of the EC-QCL. An evaluation of this laser source with regard to spectral reproducibility of consecutive scans, pulse intensity noise, and spectral resolution will be given. Furthermore, we present spectroscopic measurements in backscattering as well as in transmission geometry, demonstrating the real-time capability in different scenarios.