Journal articles: 'Quantum cascade laser, frequency comb, infrared spectroscopy'

1

Faist, Jérôme, Gustavo Villares, Giacomo Scalari, Markus Rösch, Christopher Bonzon, Andreas Hugi, and Mattias Beck. "Quantum Cascade Laser Frequency Combs." Nanophotonics 5, no. 2 (June 1, 2016): 272–91. http://dx.doi.org/10.1515/nanoph-2016-0015.

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AbstractIt was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100mW and frequency coverage of 100 cm-1 in the mid-infrared region. In the THz range, 10mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four-wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the first dual-comb spectroscopy measurements. The capability of the structure to integrate monothically nonlinear optical elements as well as to operate as a detector shows great promise for future chip integration of dual-comb systems.

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Sterczewski, Lukasz Antoni, Jonas Westberg, and Gerard Wysocki. "Tuning properties of mid-infrared Fabry-Pérot quantum cascade lasers for multiheterodyne spectroscopy." Photonics Letters of Poland 8, no. 4 (December 31, 2016): 113. http://dx.doi.org/10.4302/plp.2016.4.08.

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Injection current tuning properties of an 8.5 um Fabry-Pérot mid-infrared quantum cascade laser are evaluated by analyzing the mode-by-mode frequency tuning behavior with an identification of high-noise regimes in a delayed self-heterodyne experiment. We find that modes on the edges of the spectral envelope exhibit anomalous tuning coefficients compared to those in the center. Furthermore, the frequencies of individual modes are susceptible to parasitic etalons, likely causing laser frequency pulling. Despite the complicated tuning behavior, low phase-noise operating regimes exist, and are compatible with high resolution multiheterodyne spectroscopy of gases. Full Text: PDF ReferencesJ. Faist, F. Capasso, D.L. Sivco, C. Sirtori, A.L. Hutchinson, A.Y. Cho, "Quantum Cascade Laser", Science 264 (1994) 553?556. CrossRef A. Hugi, G. Villares, S. Blaser, H.C. Liu, J. Faist, "Mid-infrared frequency comb based on a quantum cascade laser", Nature 492 (2012) 229?233. CrossRef G. Villares, A. Hugi, S. Blaser, J. Faist,"Dual-comb spectroscopy based on quantum-cascade-laser frequency combs", Nat. Commun. 5 (2014) 5192. CrossRef G. Villares, S. Riedi, J. Wolf, D. Kazakov, M.J. Süess, P. Jouy, M. Beck, J. Faist, "Dispersion engineering of quantum cascade laser frequency combs", Optica 3 (2016) 252. CrossRef Y. Wang, M.G. Soskind, W. Wang, G. Wysocki, "High-resolution multi-heterodyne spectroscopy based on Fabry-Perot quantum cascade lasers", Appl. Phys. Lett. 104 (2014) 31114. CrossRef A. Hangauer, J. Westberg, E. Zhang, G. Wysocki, "Wavelength modulated multiheterodyne spectroscopy using Fabry-Pérot quantum cascade lasers", Opt. Express 24 (2016) 25298. CrossRef D. Burghoff, Y. Yang, D.J. Hayton, J.-R. Gao, J.L. Reno, Q. Hu, "Evaluating the coherence and time-domain profile of quantum cascade laser frequency combs", Opt. Express 23 (2015) 1190?1202. CrossRef A. Gordon, C.Y. Wang, L. Diehl, F.X. Kärtner, A. Belyanin, D. Bour, S. Corzine, G. Höfler, H.C. Liu, H. Schneider, T. Maier, M. Troccoli, J. Faist, F. Capasso, "Multimode regimes in quantum cascade lasers: From coherent instabilities to spatial hole burning", Phys. Rev. A 77 (2008). CrossRef S. Blaser, D.A. Yarekha, L. Hvozdara, Y. Bonetti, A. Muller, M. Giovannini, J. Faist, "Room-temperature, continuous-wave, single-mode quantum-cascade lasers at ?=5.4?m", Appl. Phys. Lett. 86 (2005) 41109. CrossRef S. Schiller, "Spectrometry with frequency combs", Opt. Lett. 27 (2002) 766?768. CrossRef T. Tsai, G. Wysocki, "Active wavelength control of an external cavity quantum cascade laser", Appl. Phys. B Lasers Opt. 109 (2012) 415?421. CrossRef

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Szczepaniak, Urszula, Samuel Hayes Schneider, Raphael Horvath, Jacek Kozuch, and Markus Geiser. "Vibrational Stark Spectroscopy of Fluorobenzene Using Quantum Cascade Laser Dual Frequency Combs." Applied Spectroscopy 74, no. 3 (December 23, 2019): 347–56. http://dx.doi.org/10.1177/0003702819888503.

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We demonstrate the performance of a dual frequency comb quantum cascade laser (QCL) spectrometer for the application of vibrational Stark spectroscopy. Measurements performed on fluorobenzene with the dual-comb spectrometer (DCS) were compared to results obtained using a conventional Fourier transform infrared (FT-IR) instrument in terms of spectral response, parameter estimation, and signal-to-noise ratio (S/N). The dual-comb spectrometer provided similar qualitative and quantitative data as the FT-IR setup in 250 times shorter acquisition time. For fluorobenzene, the DCS measurement resulted in a more precise estimation of the fluorobenzene Stark tuning rate ((0.81 ± 0.09) cm−1/(MV/cm)) than with the FT-IR system ((0.89 ± 0.15) cm−1/(MV/cm)). Both values are in accordance with the previously reported value of 0.84 cm−1/(MV/cm). We also point to an improvement of signal-to-noise ratio in the DCS configuration. Additional characteristics of the dual-comb spectrometer applicable to vibrational Stark spectroscopy and their scaling properties for future applications are discussed.

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Vitiello, Miriam S., Luigi Consolino, Massimo Inguscio, and Paolo De Natale. "Toward new frontiers for terahertz quantum cascade laser frequency combs." Nanophotonics 10, no. 1 (October 7, 2020): 187–94. http://dx.doi.org/10.1515/nanoph-2020-0429.

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AbstractBroadband, quantum-engineered, quantum cascade lasers (QCLs) are the most powerful chip-scale sources of optical frequency combs (FCs) across the mid-infrared and the terahertz (THz) frequency range. The inherently short intersubband upper state lifetime spontaneously allows mode proliferation, with large quantum efficiencies, as a result of the intracavity four-wave mixing. QCLs can be easily integrated with external elements or engineered for intracavity embedding of nonlinear optical components and can inherently operate as quantum detectors, providing an intriguing technological platform for on-chip quantum investigations at the nanoscale. The research field of THz FCs is extremely vibrant and promises major impacts in several application domains crossing dual-comb spectroscopy, hyperspectral imaging, time-domain nanoimaging, quantum science and technology, metrology and nonlinear optics in a miniaturized and compact architecture. Here, we discuss the fundamental physical properties and the technological performances of THz QCL FCs, highlighting the future perspectives of this frontier research field.

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Consolino, Luigi, Malik Nafa, Michele De Regis, Francesco Cappelli, Saverio Bartalini, Akio Ito, Masahiro Hitaka, et al. "Direct Observation of Terahertz Frequency Comb Generation in Difference-Frequency Quantum Cascade Lasers." Applied Sciences 11, no. 4 (February 4, 2021): 1416. http://dx.doi.org/10.3390/app11041416.

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Terahertz quantum cascade laser sources based on intra-cavity difference frequency generation from mid-IR devices are an important asset for applications in rotational molecular spectroscopy and sensing, being the only electrically pumped device able to operate in the 0.6–6 THz range without the need of bulky and expensive liquid helium cooling. Here we present comb operation obtained by intra-cavity mixing of a distributed feedback laser at λ = 6.5 μm and a Fabry–Pérot device at around λ = 6.9 μm. The resulting ultra-broadband THz emission extends from 1.8 to 3.3 THz, with a total output power of 8 μW at 78 K. The THz emission has been characterized by multi-heterodyne detection with a primary frequency standard referenced THz comb, obtained by optical rectification of near infrared pulses. The down-converted beatnotes, simultaneously acquired, confirm an equally spaced THz emission down to 1 MHz accuracy. In the future, this setup can be used for Fourier transform based evaluation of the phase relation among the emitted THz modes, paving the way to room-temperature, compact, and field-deployable metrological grade THz frequency combs.

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Fujita, Kazuue, Seungyong Jung, Yifan Jiang, Jae Hyun Kim, Atsushi Nakanishi, Akio Ito, Masahiro Hitaka, Tadataka Edamura, and Mikhail A. Belkin. "Recent progress in terahertz difference-frequency quantum cascade laser sources." Nanophotonics 7, no. 11 (September 27, 2018): 1795–817. http://dx.doi.org/10.1515/nanoph-2018-0093.

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AbstractTerahertz quantum cascade laser (QCL) sources based on intra-cavity difference frequency generation are currently the only electrically pumped monolithic semiconductor light sources operating at room temperature in the 1–6-THz spectral range. Relying on the active regions with the giant second-order nonlinear susceptibility and the Cherenkov phase-matching scheme, these devices demonstrated drastic improvements in performance in the past several years and can now produce narrow-linewidth single-mode terahertz emission that is tunable from 1 to 6 THz with power output sufficient for imaging and spectroscopic applications. This paper reviews the progress of this technology. Recent efforts in wave function engineering using a new active region design based on a dual-upper-state concept led to a significant enhancement of the optical nonlinearity of the active region for efficient terahertz generation. The transfer of Cherenkov devices from their native semi-insulating InP substrates to high-resistivity silicon substrates resulted in a dramatic improvement in the outcoupling efficiency of terahertz radiation. Cherenkov terahertz QCL sources based on the dual-upper-state design have also been shown to exhibit ultra-broadband comb-like terahertz emission spectra with more than one octave of terahertz frequency span. The broadband terahertz QCL sources operating in continuous-wave mode produces the narrow inter-mode beat-note linewidth of 287 Hz, which indicates frequency comb operation of mid-infrared pumps and thus supports potential terahertz comb operation. Finally, we report the high-quality terahertz imaging obtained by a THz imaging system using terahertz QCL sources based on intra-cavity difference frequency generation.

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Klocke, Jessica L., Markus Mangold, Pitt Allmendinger, Andreas Hugi, Markus Geiser, Pierre Jouy, Jérôme Faist, and Tilman Kottke. "Single-Shot Sub-microsecond Mid-infrared Spectroscopy on Protein Reactions with Quantum Cascade Laser Frequency Combs." Analytical Chemistry 90, no. 17 (August 6, 2018): 10494–500. http://dx.doi.org/10.1021/acs.analchem.8b02531.

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8

Norahan, Mohamad Javad, Raphael Horvath, Nathalie Woitzik, Pierre Jouy, Florian Eigenmann, Klaus Gerwert, and Carsten Kötting. "Microsecond-Resolved Infrared Spectroscopy on Nonrepetitive Protein Reactions by Applying Caged Compounds and Quantum Cascade Laser Frequency Combs." Analytical Chemistry 93, no. 17 (April 21, 2021): 6779–83. http://dx.doi.org/10.1021/acs.analchem.1c00666.

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9

Seitner, Lukas, Johannes Popp, Michael Riesch, Michael Haider, and Christian Jirauschek. "Group velocity dispersion in terahertz frequency combs within a generalized Maxwell-Bloch framework." Journal of Physics: Conference Series 2090, no. 1 (November 1, 2021): 012082. http://dx.doi.org/10.1088/1742-6596/2090/1/012082.

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Abstract As many molecules have their rotovibrational resonance frequencies in the mid-infrared or terahertz regime, efficient generation of corresponding frequency combs may lead to large progress in gas spectroscopy and sensing. Quantum cascade lasers (QCLs) are among the most promising candidates for a compact and cheap radiation source in this frequency range. This contribution presents a full-wave numerical solution of the Maxwell-Liouville-von Neumann equations, thus avoiding the limited applicability of the rotating wave approximation to moderate field strengths and spectral bandwidths. We include losses and chromatic dispersion of the optically active material in the QCL. The semiclassical approach uses the finite-difference time-domain (FDTD) method to derive update equations for the electric field, starting from the one-dimensional Maxwell equations. There, the optical full-wave propagation is coupled to the electronic quantum system via a polarization term that arises from the evolution of the density matrix. Furthermore, dispersion effects are considered through a classical polarization term and losses are introduced by a finite material conductivity. This work mainly focuses on the integration of group velocity dispersion (GVD) due to the bulk material and, if applicable, the waveguide geometry into the update equations. It is known to be one of the main degradation mechanisms of terahertz frequency combs, but has not yet been added to the existing full-wave solver. The implementation is carried out as Lorentz model and is applied to an experimentally investigated QCL frequency comb setup from the literature. The reported results are in good agreement with the experimental data. Especially, they confirm the need for dispersion compensation for the generation of terahertz frequency combs in QCLs.

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Silvestri, Carlo, Xiaoqiong Qi, Thomas Taimre, Karl Bertling, and Aleksandar D. Rakić. "Frequency combs in quantum cascade lasers: An overview of modeling and experiments." APL Photonics 8, no. 2 (February 1, 2023): 020902. http://dx.doi.org/10.1063/5.0134539.

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Over the past decade, the demonstration of frequency combs has been reported in a wide range of quantum cascade lasers. These combs have huge potential in applications, including spectroscopy, sensing, imaging, and communication domains. In this perspective review, we explore the modeling and experimental state of the art on frequency combs in mid-infrared and terahertz quantum cascade lasers, 10 years since the first demonstrations that these devices can spontaneously generate combs.

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Hugi, Andreas, Gustavo Villares, Stéphane Blaser, H. C. Liu, and Jérôme Faist. "Mid-infrared frequency comb based on a quantum cascade laser." Nature 492, no. 7428 (December 2012): 229–33. http://dx.doi.org/10.1038/nature11620.

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Meng, Bo, Matthew Singleton, Mehran Shahmohammadi, Filippos Kapsalidis, Ruijun Wang, Mattias Beck, and Jérôme Faist. "Mid-infrared frequency comb from a ring quantum cascade laser." Optica 7, no. 2 (February 3, 2020): 162. http://dx.doi.org/10.1364/optica.377755.

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13

Lu, Q. Y., S. Manna, D. H. Wu, S. Slivken, and M. Razeghi. "Shortwave quantum cascade laser frequency comb for multi-heterodyne spectroscopy." Applied Physics Letters 112, no. 14 (April 2, 2018): 141104. http://dx.doi.org/10.1063/1.5020747.

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Michaud, Sarah. "Mid-IR frequency comb and quantum-cascade laser system improves precision spectroscopy." Scilight 2018, no. 18 (April 30, 2018): 180001. http://dx.doi.org/10.1063/1.5037447.

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Lu, Q. Y., S. Manna, S. Slivken, D. H. Wu, and M. Razeghi. "Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output." AIP Advances 7, no. 4 (April 2017): 045313. http://dx.doi.org/10.1063/1.4982673.

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Galli, I., M. Siciliani de Cumis, F. Cappelli, S. Bartalini, D. Mazzotti, S. Borri, A. Montori, et al. "Comb-assisted subkilohertz linewidth quantum cascade laser for high-precision mid-infrared spectroscopy." Applied Physics Letters 102, no. 12 (March 25, 2013): 121117. http://dx.doi.org/10.1063/1.4799284.

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Schubert, Luiz, Pit Langner, David Ehrenberg, Victor A. Lorenz-Fonfria, and Joachim Heberle. "Protein conformational changes and protonation dynamics probed by a single shot using quantum-cascade-laser-based IR spectroscopy." Journal of Chemical Physics 156, no. 20 (May 28, 2022): 204201. http://dx.doi.org/10.1063/5.0088526.

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Mid-IR spectroscopy is a powerful and label-free technique to investigate protein reactions. In this study, we use quantum-cascade-laser-based dual-comb spectroscopy to probe protein conformational changes and protonation events by a single-shot experiment. By using a well-characterized membrane protein, bacteriorhodopsin, we provide a comparison between dual-comb spectroscopy and our homebuilt tunable quantum cascade laser (QCL)-based scanning spectrometer as tools to monitor irreversible reactions with high time resolution. In conclusion, QCL-based infrared spectroscopy is demonstrated to be feasible for tracing functionally relevant protein structural changes and proton translocations by single-shot experiments. Thus, we envisage a bright future for applications of this technology for monitoring the kinetics of irreversible reactions as in (bio-)chemical transformations.

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Komagata, K. N., M. Gianella, P. Jouy, F. Kapsalidis, M. Shahmohammadi, M. Beck, R. Matthey, et al. "Absolute frequency referencing in the long wave infrared using a quantum cascade laser frequency comb." Optics Express 30, no. 8 (April 4, 2022): 12891. http://dx.doi.org/10.1364/oe.447650.

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Singleton, Matthew, Mattias Beck, and Jérôme Faist. "Pulses from a mid-infrared quantum cascade laser frequency comb using an external compressor." Journal of the Optical Society of America B 36, no. 6 (May 29, 2019): 1676. http://dx.doi.org/10.1364/josab.36.001676.

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Дюделев, В. В., Д. А. Михайлов, А. В. Бабичев, С. Н. Лосев, Е. А. Когновицкая, А. В. Лютецкий, С. О. Слипченко, et al. "Динамика спектров квантово-каскадных лазеров, генерирующих частотные гребенки в длинноволновом инфракрасном диапазоне." Журнал технической физики 90, no. 8 (2020): 1333. http://dx.doi.org/10.21883/jtf.2020.08.49544.78-20.

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The studies of the spectral and dynamic characteristics of quantum-cascade lasers emitting in the long-wave infrared range are presented. It has been shown that lasers with a short resonator (~ 1 mm) generating frequency combs in a very wide spectral range. The dynamics of the the frequency comb generation mode was studied. It is shown that the intensity of the longitudinal modes of laser generation changes during the pump pulse. At the same time, simultaneous generation of all longitudinal modes of the frequency comb during flat part of the pumping pulse is observed.

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Ma, Yu, Wei-Jiang Li, Yun-Fei Xu, Jun-Qi Liu, Ning Zhuo, Ke Yang, Jin-Chuan Zhang, et al. "Flat Top Optical Frequency Combs Based on a Single-Core Quantum Cascade Laser at Wavelength of ∼ 8.7 μm." Chinese Physics Letters 40, no. 1 (January 1, 2023): 014201. http://dx.doi.org/10.1088/0256-307x/40/1/014201.

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We present optical frequency combs with a spectral emission of 48 cm−1 and an output power of 420 mW based on a single-core quantum cascade laser at λ ∼ 8.7 μm. A flat top spectrum sustains up to 130 comb modes delivering ∼ 3.2 mW of optical power per mode, making it a valuable tool for dual comb spectroscopy. The homogeneous gain medium, relying on a slightly diagonal bound-to-continuum structure, promises to provide a broad and stable gain for comb operating. Remarkably, the dispersion of this device is measured within 300 fs2/mm to ensure stable comb operation over 90% of the total current range. The comb is observed with a narrow beatnote linewidth around 2 kHz and has weak dependence on the applied current for stable comb operation.

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Peng, Chen, Gang Chen, Jianping Tang, Lijun Wang, Zhongquan Wen, Haijun Zhou, and Rainer Martini. "High-Speed Mid-Infrared Frequency Modulation Spectroscopy Based on Quantum Cascade Laser." IEEE Photonics Technology Letters 28, no. 16 (August 15, 2016): 1727–30. http://dx.doi.org/10.1109/lpt.2016.2554359.

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23

Lu, Q. Y., M. Razeghi, S. Slivken, N. Bandyopadhyay, Y. Bai, W. J. Zhou, M. Chen, et al. "High power frequency comb based on mid-infrared quantum cascade laser at λ ∼ 9 μm." Applied Physics Letters 106, no. 5 (February 2, 2015): 051105. http://dx.doi.org/10.1063/1.4907646.

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Dal Cin, Sandro, Florian Pilat, Aleš Konečný, Nikola Opačak, Gottfried Strasser, and Benedikt Schwarz. "Coherent control of transverse modes in semiconductor laser frequency combs via radio-frequency injection." Applied Physics Letters 121, no. 7 (August 15, 2022): 071106. http://dx.doi.org/10.1063/5.0098474.

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Increasing the output power of semiconductor laser frequency combs, while maintaining a single-lobe far-field characteristic is of great interest for mid-infrared sensing applications. Broadening of the ridge waveguide represents the most common approach for power scaling, however, the excitement of higher-order transverse modes often limits general applicability. Here, we demonstrate that the coherent control of the longitudinal laser modes enables control over the transverse modes of a quantum cascade laser. Modulating the laser in a frequency range 60 ± 3 MHz above the free-running laser beatnote and applying modulation powers above 25 dBm provides reliable fundamental transverse mode operation, observable as single-lobe, Gaussian-like characteristic in the recorded far-field. Furthermore, coherent comb operation for both fundamental and higher-order transverse mode states is demonstrated.

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Corrias, Nicola, Tecla Gabbrielli, Paolo De Natale, Luigi Consolino, and Francesco Cappelli. "Analog FM free-space optical communication based on a mid-infrared quantum cascade laser frequency comb." Optics Express 30, no. 7 (March 14, 2022): 10217. http://dx.doi.org/10.1364/oe.443483.

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Shehzad, Atif, Pierre Brochard, Renaud Matthey, Filippos Kapsalidis, Mehran Shahmohammadi, Mattias Beck, Andreas Hugi, et al. "Frequency noise correlation between the offset frequency and the mode spacing in a mid-infrared quantum cascade laser frequency comb." Optics Express 28, no. 6 (March 5, 2020): 8200. http://dx.doi.org/10.1364/oe.385849.

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Knabe, Kevin, Paul A. Williams, Fabrizio R. Giorgetta, Michael B. Radunsky, Chris M. Armacost, Sam Crivello, and Nathan R. Newbury. "Absolute spectroscopy of N_2O near 45 μm with a comb-calibrated, frequency-swept quantum cascade laser spectrometer." Optics Express 21, no. 1 (January 9, 2013): 1020. http://dx.doi.org/10.1364/oe.21.001020.

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Gatti, D., A. Gambetta, A. Castrillo, G. Galzerano, P. Laporta, L. Gianfrani, and M. Marangoni. "High-precision molecular interrogation by direct referencing of a quantum-cascade-laser to a near-infrared frequency comb." Optics Express 19, no. 18 (August 22, 2011): 17520. http://dx.doi.org/10.1364/oe.19.017520.

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Koziol, Paulina, Magda K. Raczkowska, Justyna Skibinska, Nicholas J. McCollum, Slawka Urbaniak-Wasik, Czeslawa Paluszkiewicz, Wojciech M. Kwiatek, and Tomasz P. Wrobel. "Denoising influence on discrete frequency classification results for quantum cascade laser based infrared microscopy." Analytica Chimica Acta 1051 (March 2019): 24–31. http://dx.doi.org/10.1016/j.aca.2018.11.032.

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Bertrand, Mathieu, Aleksandr Shlykov, Mehran Shahmohamadi, Mattias Beck, Stefan Willitsch, and Jérôme Faist. "High-Power, Narrow-Linewidth Distributed-Feedback Quantum-Cascade Laser for Molecular Spectroscopy." Photonics 9, no. 8 (August 19, 2022): 589. http://dx.doi.org/10.3390/photonics9080589.

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Quantum cascade lasers are versatile light sources in the mid-infrared range for molecular spectroscopy which find a wide range of applications from high-resolution studies to sensing. While devices with either high power or narrow spectral linewidth have previously been reported, there is still a lack of sources combining both of these characteristics which are particularly important for precision measurements of weak spectroscopic transitions. In this article, we describe and characterize a novel master-oscillator power-amplifier distributed-feedback quantum cascade laser designed to fill this gap. At an output power of 300 mW, the device features a free-running linewidth of 1.3 MHz, measured with a frequency discriminator technique, at an emission wavenumber of 2185 cm−1. This linewidth is sufficiently narrow to enable a further reduction by a tight lock to a high-Q oscillator.

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Koyama, Takuya, Naoto Shibata, Saiko Kino, Atsushi Sugiyama, Naota Akikusa, and Yuji Matsuura. "A Compact Mid-Infrared Spectroscopy System for Healthcare Applications Based on a Wavelength-Swept, Pulsed Quantum Cascade Laser." Sensors 20, no. 12 (June 18, 2020): 3438. http://dx.doi.org/10.3390/s20123438.

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A mid-infrared spectroscopic system using a high-speed wavelength-swept and pulsed quantum cascade laser (QCL) for healthcare applications such as blood glucose measurement is proposed. We developed an attenuated total reflection measurement system comprising the QCL with a micro-electromechanical system (MEMS)-scanning grating, hollow optical fibers, and InAsSb detector and tested its feasibility for healthcare applications. A continuous spectrum was obtained by integrating comb-shaped spectra, the timing of which was slightly shifted. As this method does not require complex calculations, absorption spectra are obtained in real-time. We found that the signal-to-noise ratio of the obtained spectrum had been improved by increasing the number of spectra that were integrated into the spectrum calculation. Accordingly, we succeeded in measuring the absorption spectrum of a 0.1% aqueous glucose solution. Furthermore, the absorption spectra of human lips were measured, and it was shown that estimation of blood glucose levels were possible using a model equation derived using a partial least squares regression analysis of the measured absorption spectra. The spectroscopic system based on the QCL with MEMS-scanning grating has the advantages of compactness and low cost over conventional Fourier transform infrared-based systems and common spectroscopic systems with a tunable QCL that has a relatively large, movable grating.

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Mikołajczyk, Janusz, and Dariusz Szabra. "Integrated IR Modulator with a Quantum Cascade Laser." Applied Sciences 11, no. 14 (July 13, 2021): 6457. http://dx.doi.org/10.3390/app11146457.

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This paper presents an infrared pulsed modulator into which quantum cascade lasers and a current driver are integrated. The main goal of this study was to determine the capabilities of a new modulator design based on the results of its electrical model simulation and laboratory experiments. A simulation model is a unique tool because it includes the electrical performance of the lasing structure, signal wiring, and driving unit. In the laboratory model, a lasing structure was mounted on the interfacing poles as close to the switching electronics as possible with direct wire bonding. The radiation pulses and laser biasing voltage were registered to analyze the influence of laser module impedance. Both simulation and experimental results demonstrated that the quantum cascade laser (QC laser) design strongly influenced the shape of light, driving current, and biasing voltage pulses. It is a complex phenomenon depending on the laser construction and many other factors, e.g., the amplitude and time parameters of the supplying current pulses. However, this work presents important data to develop or modify numerical models describing QC laser operation. The integrated modulator provided pulses with a 20–100 ns duration and a frequency of 1 MHz without any active cooling. The designed modulator ensured the construction of a sensor based on direct laser absorption spectroscopy, applying the QC laser with spectral characteristics matched to absorption lines of the detected substances. It can also be used in optical ranging and recognition systems.

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Gambetta, A., D. Gatti, A. Castrillo, G. Galzerano, P. Laporta, L. Gianfrani, and M. Marangoni. "Mid-infrared quantitative spectroscopy by comb-referencing of a quantum-cascade-laser: Application to the CO2 spectrum at 4.3 μm." Applied Physics Letters 99, no. 25 (December 19, 2011): 251107. http://dx.doi.org/10.1063/1.3671081.

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Terabayashi, Ryohei, Keisuke Saito, Volker Sonnenschein, Yuki Okuyama, Kazuki Iwamoto, Kazune Mano, Yuta Kawashima, et al. "V-cavity stabilized quantum cascade laser-based cavity ringdown spectroscopy for rapid detection of radiocarbon below natural abundance." Journal of Applied Physics 132, no. 8 (August 28, 2022): 083102. http://dx.doi.org/10.1063/5.0101732.

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Mid-infrared laser absorption spectroscopy utilizing a high-finesse optical cavity enables high precision trace analysis of gas molecules. In particular, optical detection of radiocarbon (14C) based on cavity ringdown spectroscopy using a quantum cascade laser (QCL) is gaining attention as an alternative to accelerator mass spectrometry. This paper reports a compact-packaged narrow-linewidth QCL system utilizing resonant optical feedback from an external V-shaped cavity. Based on frequency noise analysis, the derived laser linewidth is 44 kHz for 100 μs integration time with the capability to perform seamless frequency scanning around 10 GHz. We installed this laser system within a table-top cavity ringdown spectrometer for 14CO2. A single-shot detection limit of 1.2 × 10−9 cm−1 Hz−1/2 leading to a detectable abundance evaluated from a noise analysis of 0.2 in fraction modern 14C for a 10-s averaging time was achieved. This capability of rapid analysis for 14CO2 is suitable for various applications requiring trace 14C analysis.

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Wang, Zhen, Kin-Pang Cheong, Mingsheng Li, Qiang Wang, and Wei Ren. "Theoretical and Experimental Study of Heterodyne Phase-Sensitive Dispersion Spectroscopy with an Injection-Current-Modulated Quantum Cascade Laser." Sensors 20, no. 21 (October 29, 2020): 6176. http://dx.doi.org/10.3390/s20216176.

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We report the theoretical and experimental study of calibration-free heterodyne phase-sensitive dispersion spectroscopy (HPSDS) in the mid-infrared using a direct current modulated mid-infrared quantum cascade laser (QCL). The modulation of QCL current at several hundred MHz or higher generates the synchronous frequency and intensity modulation of the QCL emission. An analytical model of the phase of the beat note signal in HPSDS is derived by considering the absorption and dispersion processes and incorporating the QCL modulation parameters. In the experiment, a 4.5 μm QCL modulated at 350 MHz was used to measure N2O at 200 Torr in a 10 cm gas cell. The N2O concentrations inferred from the analytical model were compared with the nominal values to show good agreement over the concentration range of 189−805 ppm with a standard deviation <3%. When the QCL wavelength was locked at the line-center of the molecular transition, it was of interest to find that the theoretical model was simplified to that used for near-infrared HPSDS with an electro-optical modulator for laser modulation.

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Hu, Mengyuan, Andrea Ventura, Juliano Grigoleto Hayashi, Francesco Poletti, and Wei Ren. "Mid-Infrared Frequency Modulation Spectroscopy of NO Detection in a Hollow-Core Antiresonant Fiber." Photonics 9, no. 12 (December 3, 2022): 935. http://dx.doi.org/10.3390/photonics9120935.

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Mid-infrared frequency modulation spectroscopy (FMS) in a tellurite hollow-core antiresonant fiber (HC-ARF) is investigated for gas detection. The spectroscopic system is demonstrated for nitric oxide (NO) detection by exploiting its strong absorption line at 1900.08 cm−1 with a quantum cascade laser (QCL). By modulating the injection current of the QCL at 250 MHz and measuring NO in a 35 cm long HC-ARF, we achieve a noise equivalent concentration of 67 ppb at an averaging time of 0.1 s. Compared to direct absorption spectroscopy with a low-pass filter for etalon noise reduction, the FMS technique shows an improvement factor of 22. The detection limit of FMS can be further improved to 6 ppb at a longer averaging time of 100 s, corresponding to a noise equivalent absorption coefficient of 1.0 × 10−7 cm−1.

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Gambetta, Alessio, Marco Cassinerio, Nicola Coluccelli, Eugenio Fasci, Antonio Castrillo, Livio Gianfrani, Davide Gatti, Marco Marangoni, Paolo Laporta, and Gianluca Galzerano. "Direct phase-locking of a 86-μm quantum cascade laser to a mid-IR optical frequency comb: application to precision spectroscopy of N_2O." Optics Letters 40, no. 3 (January 19, 2015): 304. http://dx.doi.org/10.1364/ol.40.000304.

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Wang, Min, Jie Chen, Niu Liu, and Ya Wang. "Inter-Pulse Spectroscopy Based on Room-Temperature Pulsed Quantum-Cascade Laser for N₂O Detection." Applied Mechanics and Materials 128-129 (October 2011): 607–10. http://dx.doi.org/10.4028/www.scientific.net/amm.128-129.607.

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Mid-infrared lasers are very suitable for high-sensitive trace-gases detection for their wavelengths cover the fundamental absorption lines of most gases. Quantum-cascade (QC) lasers have been demonstrated to be ideal light sources with its special power, tuning and capability of operating in room-temperature. All these merits make it appropriate for the high resolution spectrum analysis. The absorption spectrum monitoring technology based on the QC laser pulsed operating in the room temperature, combining with the strong absorption of the gas molecule in the basic frequency, has become an effective way to monitor the trace gas with the characteristic of high sensitivity, good selectivity and fast response. In this paper, the inter-pulse spectroscopy based on a room-temperature distributed-feedback pulsed QC laser was introduced. Our approach to trace gas monitoring with QC lasers relies on short current pulses which are designed to produce even shorter light pulses. Each pulse corresponds to a single point in a spectrum. The N2O absorption spectrum centered at 2178.2cm-1was also obtained.

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Sun, Qibing, Wei Wu, Yi Wang, Yu Yang, Lei Shi, Xianshun Ming, Leiran Wang, Keyi Wang, Wei Zhao, and Wenfu Zhang. "Mid-infrared optical parametric oscillation spanning 3.4–8.2 μm in a MgF₂ microresonator." Nanotechnology 33, no. 21 (March 4, 2022): 210003. http://dx.doi.org/10.1088/1361-6528/ac52bf.

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Abstract Mid-infrared optical parametric oscillators (OPOs) offer a compelling route for accessing the ‘molecular fingerprint’ region and, thus, can find intensive applications such as precision spectroscopy and trace gas detection. Yet it still remains rather a challenge to realize broadband mid-infrared OPOs within a single cavity, usually limited by strict phase-matching conditions for wide spectral coverage and available pump power for adequate frequency generation. Here, we report the mid-infrared parametric oscillation spanning from 3.4 to 8.2 μm, based on four-wave mixing in a high-Q MgF2 microresonator with optimized dispersion. The center wavelength at 4.78 μm is determined by the continuous tunable quantum cascade laser source, which contributes to effective expansion towards longer wavelength, as well as systemic miniaturization with smaller pump module. Such results could not only shed light on new ultimates of crystal and other microresonators, but also inspire explorations on their growing potentials in near future.

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Kroon, P. S., A. Hensen, H. J. J. Jonker, M. S. Zahniser, W. H. van 't Veen, and A. T. Vermeulen. "Suitability of quantum cascade laser spectroscopy for CH<sub>4</sub> and N<sub>2</sub>O eddy covariance flux measurements." Biogeosciences 4, no. 5 (August 31, 2007): 715–28. http://dx.doi.org/10.5194/bg-4-715-2007.

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Abstract. A quantum cascade laser spectrometer was evaluated for eddy covariance flux measurements of CH4 and N2O using three months of continuous measurements at a field site. The required criteria for eddy covariance flux measurements including continuity, sampling frequency, precision and stationarity were examined. The system operated continuously at a dairy farm on peat grassland in the Netherlands from 17 August to 6 November 2006. An automatic liquid nitrogen filling system for the infrared detector was employed to provide unattended operation of the system. The electronic sampling frequency was 10 Hz, however, the flow response time was 0.08 s, which corresponds to a bandwidth of 2 Hz. A precision of 2.9 and 0.5 ppb Hz−1/2 was obtained for CH4 and N2O, respectively. Accuracy was assured by frequent calibrations using low and high standard additions. Drifts in the system were compensated by using a 120 s running mean filter. The average CH4 and N2O exchange was 512 ngC m−2 s−1 (2.46 mg m−2 hr−1) and 52 ngN m−2 s−1 (0.29 mg m−2 hr−1). Given that 40% of the total N2O emission was due to a fertilizing event.

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Barzaghi, Andrea, Virginia Falcone, Stefano Calcaterra, Raffaele Giani, Andrea Ballabio, Giovanni Isella, Daniel Chrastina, Michele Ortolani, Michele Virgilio, and Jacopo Frigerio. "Germanium Quantum Wells for Non-Linear Integrated Photonics." ECS Meeting Abstracts MA2022-02, no. 32 (October 9, 2022): 1176. http://dx.doi.org/10.1149/ma2022-02321176mtgabs.

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In recent years, mid-infrared integrated photonics has raised an increasing interest due to the envisioned applications in molecular sensing, environmental monitoring and security. The Silicon-on-insulator (SOI) based technology, operating at wavelengths λ < 3.2 μm has already reached a significant technology readiness level. By leveraging the maturity of the SOI technology and taking advantage of the high index contrast between Si and SiO2 many functionalities such as low loss waveguiding, modulation and frequency comb generation have already been demonstrated. However, the wavelength range is limited by the absorption of the SiO2 layer. Many material platforms, such as III-V semiconductors, halides and chalcogenides are under investigation to fill this gap. Of particular interest is the Ge-rich SiGe-on-Si material platform, thanks to its compatibility to already existing foundry processes and its wide transparency at the wavelengths of interest. Nevertheless, key functionalities such as wavelength conversion, photodetection and high-speed modulation are still missing. A viable way to achieve such advanced functionalities is the exploitation of intersubband transitions (ISBTs) in hole-doped Ge/SiGe quantum wells (QWs). In particular, ISBTs in can be leveraged to engineer an artificial second-order optical nonlinearity in group IV materials, where it is normally absent for symmetry reasons. In this work, we exploit ISBTs in asymmetric coupled Ge/SiGe (ACQWs) (see Fig.1) to achieve highly efficient second harmonic generation at mid-infrared frequencies. The ACQW has been designed with an advanced semi-empirical first neighbor sp3d5s* tight-binding model, which has been used to calculate the second-order nonlinear susceptibility χ(2) (see fig 1b). The ACQW has been then grown by Low-Energy Plasma-Enhanced Chemical Vapor Deposition (LEPECVD) and structurally characterized by x-ray diffraction (XRD) and high-resolution scanning transmission electron microscopy (STEM) . For the optical measurements, samples were cut in a 2 mm single-pass surface-plasmon waveguide with the side facets shaped to 70° with respect to the growth plane and the top facet close to the ACQWs region coated by a Ti/Au layer. Then the samples (cooled at 10 K) have been pumped with a CW quantum cascade laser emitting at λ =10.3 μm. The light coming out from the samples have been then filtered and collected by an MCT detector. The second harmonic emission has been recorded as a function of the input power (see fig. 1c) and a c(2) = 6x104 pm/V has been extracted from the measurement, a two orders of magnitude improvement with respect to the best nonlinear crystals. Finally, the possibility to integrate ACQWs in waveguides has been theoretically investigated. Since artificial nonlinearities based on ISBTs involve real quantum states, as opposite to the virtual quantum states employed in standard nonlinear crystals, significative optical absorption at the pump and at the second harmonic wavelengths must be considered. Therefore, the length of the ACQW waveguide must be carefully designed in order to limit the optical losses. By solving the coupled wave equations with optical absorption at the pump and second harmonic wavelengths, we show that high conversion efficiencies around ≈ 10% can be achieved with waveguide integrated ACQWs for an optimal waveguide length of a ≈200 μm. The integration scheme, shown in fig 2a, consists in a stack of ACQW integrated in a waveguide containing a periodic corrugation, which is necessary to achieve quasi-phase matching between the pump and the second harmonic. Input and output coupling of the light is achieved through adiabatic tapers by integrating the ACQW stack on a Si0.3Ge0.7 waveguide, where the light is injected and from which it is collected and measured. The pump and the second harmonic mode are fairly overlapped in the ACQW region, as shown in fig 2b and 2c, where the distribution of the first TM mode has been simulated using the Lumerical software package. In conclusion, Ge/SiGe ACQW are very promising to expand the functionalities available in MIR integrated photonic circuits, especially in the important spectral region up to 10 μm. In particular, the experimental data obtained from the material characterization, as well as the preliminary studies of waveguide integration show that Ge/SiGe ACQW has the potential to realize highly efficient integrated wavelength converters. Acknowledgments: This work has been supported by Fondazione Cariplo, grant n° 2020-4427. Figure 1

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Bartalini, S., L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, et al. "Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy." Physical Review X 4, no. 2 (April 9, 2014). http://dx.doi.org/10.1103/physrevx.4.021006.

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Villares, Gustavo, Andreas Hugi, Stéphane Blaser, and Jérôme Faist. "Dual-comb spectroscopy based on quantum-cascade-laser frequency combs." Nature Communications 5, no. 1 (October 13, 2014). http://dx.doi.org/10.1038/ncomms6192.

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Zhou, Lian, Yang Liu, Gehui Xie, Chenglin Gu, Zejiang Deng, Zhiwei Zhu, Cheng Ouyang, et al. "Mid-infrared optical frequency comb in the 2.7–4.0 μm range via difference frequency generation from a compact laser system." High Power Laser Science and Engineering 8 (2020). http://dx.doi.org/10.1017/hpl.2020.32.

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Abstract We report on the generation of a mid-infrared (mid-IR) frequency comb with a maximum average output power of 250 mW and tunability in the 2.7–4.0 μm region. The approach is based on a single-stage difference frequency generation (DFG) starting from a compact Yb-doped fiber laser system. The repetition rate of the near-infrared (NIR) comb is locked at 75 MHz. The phase noise of the repetition rate in the offset-free mid-IR comb system is measured and analyzed. Except for the intrinsic of NIR comb, environmental noise at low frequency and quantum noise at high frequency from the amplifier chain and nonlinear spectral broadening are the main noise sources of broadening the linewidth of comb teeth, which limits the precision of mid-IR dual-comb spectroscopy.

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Yu, Ma, Li Wei-Jiang, Xu Yun-Fei, Liu Jun-Qi, Zhuo Ning, Yang Ke, Zhang Jin-Chuan, et al. "Flat top optical frequency combs based on a single-core quantum cascade laser at the wavelength of ~8.7 μm." Chinese Physics Letters, November 23, 2022. http://dx.doi.org/10.1088/0256-307x/40/01/014201.

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Abstract We present optical frequency combs with a spectral emission of 48 cm-1 and an output power of 420 mW based on a single-core quantum cascade laser at λ~8.7 μm. A flat top spectrum sustains up to 130 comb modes delivering ~3.2 mW of optical power per mode, making it a valuable tool for dual comb spectroscopy. The homogeneous gain medium, relying on a slightly-diagonal bound-to-continuum structure, promises to provide broad and stable gain for comb operating. Remarkably, the dispersion of this device is measured within 300 fs2/mm to ensure stable comb operation over 90% of the total current range. The comb is observed with a narrow beatnote linewidth around 2 kHz and has weak dependence on the applied current for stable comb operation.

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Shim, Euijae, Andres Gil-Molina, Ohad Westreich, Yamac Dikmelik, Kevin Lascola, Alexander L. Gaeta, and Michal Lipson. "Tunable single-mode chip-scale mid-infrared laser." Communications Physics 4, no. 1 (December 2021). http://dx.doi.org/10.1038/s42005-021-00770-6.

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AbstractPortable mid-infrared (mid-IR) spectroscopy and sensing applications require widely tunable, chip-scale, single-mode sources without sacrificing significant output power. However, no such lasers have been demonstrated beyond 3 μm due to the challenge of building tunable, high quality-factor (Q) on-chip cavities. Here we demonstrate a tunable, single-mode mid-IR laser at 3.4 μm using a tunable high-Q silicon microring cavity and a multi-mode Interband Cascade Laser. We achieve single-frequency lasing with 0.4 mW output power via self-injection locking and a wide tuning range of 54 nm with 3 dB output power variation. We further estimate an upper-bound effective linewidth of 9.1 MHz and a side mode suppression ratio of 25 dB from the locked laser using a scanning Fabry-Perot interferometer. Our laser platform based on a tunable high-Q microresonator can be expanded to higher wavelength quantum-cascade lasers and lead to the development of compact, high-performance mid-IR sensors for spectroscopic applications.

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Lei, Hongbin, Jinping Yao, Jing Zhao, Hongqiang Xie, Fangbo Zhang, He Zhang, Ning Zhang, et al. "Ultraviolet supercontinuum generation driven by ionic coherence in a strong laser field." Nature Communications 13, no. 1 (July 14, 2022). http://dx.doi.org/10.1038/s41467-022-31824-0.

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AbstractSupercontinuum (SC) light sources hold versatile applications in many fields ranging from imaging microscopic structural dynamics to achieving frequency comb metrology. Although such broadband light sources are readily accessible in the visible and near infrared regime, the ultraviolet (UV) extension of SC spectrum is still challenging. Here, we demonstrate that the joint contribution of strong field ionization and quantum resonance leads to the unexpected UV continuum radiation spanning the 100 nm bandwidth in molecular nitrogen ions. Quantum coherences in a bunch of ionic levels are found to be created by dynamic Stark-assisted multiphoton resonances following tunneling ionization. We show that the dynamical evolution of the coherence-enhanced polarization wave gives rise to laser-assisted continuum emission inside the laser field and free-induction decay after the laser field, which jointly contribute to the SC generation together with fifth harmonics. As proof of principle, we also show the application of the SC radiation in the absorption spectroscopy. This work offers an alternative scheme for constructing exotic SC sources, and opens up the territory of ionic quantum optics in the strong-field regime.

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Riepl, J., J. Raab, P. Abajyan, H. Nong, J. R. Freeman, L. H. Li, E. H. Linfield, et al. "Field-resolved high-order sub-cycle nonlinearities in a terahertz semiconductor laser." Light: Science & Applications 10, no. 1 (December 2021). http://dx.doi.org/10.1038/s41377-021-00685-5.

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AbstractThe exploitation of ultrafast electron dynamics in quantum cascade lasers (QCLs) holds enormous potential for intense, compact mode-locked terahertz (THz) sources, squeezed THz light, frequency mixers, and comb-based metrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operational THz QCLs. Here, we employ high-field THz pulses to perform the first ultrafast two-dimensional spectroscopy of a free-running THz QCL. Strong incoherent and coherent nonlinearities up to eight-wave mixing are detected below and above the laser threshold. These data not only reveal extremely short gain recovery times of 2 ps at the laser threshold, they also reflect the nonlinear polarization dynamics of the QCL laser transition for the first time, where we quantify the corresponding dephasing times between 0.9 and 1.5 ps with increasing bias currents. A density-matrix approach reproducing the emergence of all nonlinearities and their ultrafast evolution, simultaneously, allows us to map the coherently induced trajectory of the Bloch vector. The observed high-order multi-wave mixing nonlinearities benefit from resonant enhancement in the absence of absorption losses and bear potential for a number of future applications, ranging from efficient intracavity frequency conversion, mode proliferation to passive mode locking.

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Journal articles on the topic 'Quantum cascade laser, frequency comb, infrared spectroscopy'

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