Gas spectroscopy with integrated frequency monitoring through self-mixing in a terahertz quantum-cascade laser

作者：Chhantyal Pun Rabi; Valavanis Alexander^*; Keeley James T; Rubino Pierluigi; Kundu Iman; Han Yingjun; Dean Paul; Li Lianhe; Davies A Giles; Linfield Edmund H

来源：Optics Letters, 2018, 43(10): 2225-2228.

DOI：10.1364/OL.43.002225

We demonstrate a gas spectroscopy technique, using self-mixing in a 3.4 terahertz quantum-cascade laser (QCL). All previous QCL spectroscopy techniques have required additional terahertz instrumentation (detectors, mixers, or spectrometers) for system pre-calibration or spectral analysis. By contrast, our system self-calibrates the laser frequency (i.e., with no external instrumentation) to a precision of 630 MHz (0.02%) by analyzing QCL voltage perturbations in response to optical feedback within a 0-800 mm round-trip delay line. We demonstrate methanol spectroscopy by introducing a gas cell into the feedback path and show that a limiting absorption coefficient of similar to 1 x 10(-4) cm(-1) is resolvable. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.

• 出版日期2018-5-15