CC BY
12THz-I-11
High resolution spectroscopy based on frequency sweeping with using THz quantum cascade lasers
V.Vaks1, V.A.Anfertev1, E.G.Domracheva1, S.I.Pripolzin1, M.B.Chernyaeva1, A.Baranov2
1 -IPMRAS, 7, Akademicheskaya str., Afonino village, Nizhny Novgorod region, 603087Russia 2-Institute of Electronics and Systems (IES), UMR 5214 CNRS - University of Montpellier, France
vax@ipmras. ru
Actual problems in the gas analysis are associated with developing the methods of analysis of multicomponent gas mixtures for various applications including the spectroscopy methods. The main problem of high precise spectroscopy is development of high-stable tunable coherent radiation sources. The modern spectroscopic requirements to THz radiation sources are frequency stabilization with accuracy ~10-8 -10-10 from carrier frequency, Doppler resolution, high spectral purity and smooth tuning of frequency in wide frequency range.
The development of semiconductor technology will allow achieving a high level for production of the radiation sources and detectors for terahertz spectroscopy. The review of modern semiconductor radiation sources of THz ranges is presented.
The special consideration is given to possibility of using the behavior THz quantum cascade lasers (QCL) for application in spectroscopy. QCL working in continuous and pulse modes will be used for THz frequency range. The development of THz emitters based on QCL up to 3-4 THz is presented. One of the promising methods for high resolution spectroscopy is approach on the base of fast frequency sweeping [1]. Fast frequency sweeping mode is the method of detecting the spectrum in sufficiently wide frequency range during the short time (about milliseconds) in current importance. This approach is used in high resolution gas spectroscopy in low frequency part of terahertz frequency range [2], in particular, at the analysis of multicomponent gas mixtures allowing to detect all substances, which have intensive absorption lines lying in frequency range of spectrometer and which are presented in gas mixtures at recording the spectrum. QCL working in pulse mode allows to realize the frequency sweeping of radiation. The possibility of elaboration of THz spectrometer with radiation source with fast sweeping mode based on THz QCL is investigated.
Elaboration of new semiconductor radiation sources allows developing the THz nonstationary spectroscopy for fast analysis of composition of multicomponent gas mixture, that can be important for various applications. In particularly it is important for medical diagnostics where this approach allows to detect such substances are, e.g., metabolites concerned with cancer disease for its early diagnostics.
The authors acknowledge the support from Russian Foundation for Basic Research (grant N18-52-16017).
[1] V. Khodos, D. Ryndyk, V. Vaks. Fast passage microwave molecular spectroscopy with frequency sweeping. Eur.Phys.J.Appl.Phys. vol. 25. pp. 203-208, (2004).
[2] V. Vaks, V. Anfertev, V. Balakirev, S. Basov, E. Domracheva, A. Illyuk, P. Kupriyanov, S. Pripolzin, M. Chernyaeva. High resolution terahertz spectroscopy for analytical applications. Phys. Usp. vol. 63, pp. 708-720, (2020).
