Quantum cascade lasers comb spectrometers
Prof Jérôme Faist, Quantum Optoelectronics Group, ETH Zurich, Switzerland
The quantum cascade laser has demonstrated operation over an extremely wide wavelength range extending from the mid-infrared at 2.9 μm to the Terahertz at 360 μm. One very important feature of this device is its ability to provide gain over a very broad wavelength range. Recently, we have shown that such broadband devices, when operated in continuous wave, emit as a coherent optical comb  in which the phase relation between the comb modes corresponds approximately to a FM modulated laser. These new comb lasers enables the fabrication of a dual comb spectrometer based on a quantum cascade laser that offers a broadband, all solid-state spectrometer with no moving parts and a ultrafast acquisition time. We discuss also the extension of these ideas to the THz.
 A. Hugi, G. Villares, S. Blaser, H. C. Liu and J. Faist, Nature 492 (7428), 229-233 (2012).
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