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1. A mid-infrared dual-comb spectrometer in step-sweep mode for high-resolution molecular spectroscopy

Author

Lepère, Muriel, Browet, Olivier, Clément, Jean, Vispoel, Bastien, Allmendinger, Pitt, Hayden, Jakob, Eigenmann, Florian, Hugi, Andreas, and Mangold, Markus

Subjects
Physics - Optics, Physics - Instrumentation and Detectors
Abstract

To meet the challenges of high-resolution molecular spectroscopy, increasingly sophisticated spectroscopic techniques were developed. For a long time FTIR and laser-based spectroscopies were used for these studies. The recent development of dual-comb spectroscopy at high-resolution makes this technique a powerful tool for gas phase studies. We report on the use and characterization of the IRis-F1, a tabletop mid-infrared dual-comb spectrometer, in the newly developed step-sweep mode. The resolution of the wavenumber axis is increased by step-wise tuning (interleaving) and accurate measurement of the laser center wavelength and repetition frequency. Doppler limited measurements of N2O and CH4 reveal a wavenumber accuracy of 1E-4 cm-1 on the covered range of > 50 cm-1. Measured half-widths of absorption lines show no systematic broadening, indicating a negligible instrument response function. Finally, measurements of nitrogen pressure broadening coefficients in the v4 band of methane show that quantum cascade laser dual-comb spectroscopy in step-sweep mode is well adapted for measurements of precision spectroscopic data, in particular line shape parameters.

Published
2024
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2. Dual-comb Spectroscopy of Ammonia Formation in Non-thermal Plasmas

Author

Sadiek, Ibrahim, Fleisher, Adam J., Hayden, Jakob, Huang, Xinyi, Hugi, Andreas, Engeln, Richard, Lang, Norbert, and van Helden, Jean-Pierre H.

Subjects
Physics - Chemical Physics
Abstract

Plasma-activated chemical transformations promise the efficient synthesis of salient chemical products. However, the reaction pathways that lead to desirable products are often unknown, and key quantum-state-resolved information regarding the involved molecular species is lacking. Here we use quantum cascade laser dual-comb spectroscopy (QCL-DCS) to probe plasma-activated NH$_3$ generation with rotational and vibrational state resolution, quantifying state-specific number densities via broadband spectral analysis. The measurements reveal unique translational, rotational and vibrational temperatures for NH$_3$ products, indicative of a highly reactive, non-thermal environment. Ultimately, we postulate on the energy transfer mechanisms that explain trends in temperatures and number densities observed for NH$_3$ generated in low-pressure nitrogen-hydrogen (N$_2$-H$_2$) plasmas.

Published
2023
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4. High-resolution and gapless dual comb spectroscopy with current-tuned quantum cascade lasers

Author

Gianella, Michele, Nataraj, Akshay, Tuzson, Béla, Jouy, Pierre, Kapsalidis, Filippos, Beck, Mattias, Mangold, Markus, Hugi, Andreas, Faist, Jérôme, and Emmenegger, Lukas

Subjects
Physics - Applied Physics, Physics - Optics
Abstract

We present gapless, high-resolution absorption and dispersion spectra obtained with quantum cascade laser frequency combs covering 55 cm$^{-1}$. Using phase-sensitive dual comb design, the comb lines are gradually swept over 10 GHz, corresponding to the free spectral range of the laser devices, by applying a current modulation. We show that with interleaving the spectral point spacing is reduced by more than four orders of magnitude over the full spectral span of the frequency comb. The potential of this technique for high-precision gas sensing is illustrated by measuring the low pressure (107 hPa) absorption and dispersion spectra of methane spanning the range of 1170 cm$^{-1}$ - 1225 cm$^{-1}$ with a resolution of 0.001 cm$^{-1}$.

Published
2019
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7. Quantum Cascade Laser Frequency Combs

Author

Faist, Jérôme, Villares, Gustavo, Scalari, Giacomo, Rösch, Markus, Bonzon, Christopher, Hugi, Andreas, and Beck, Mattias

Subjects
Physics - Optics
Abstract

It 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 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW 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 monolithically non-linear optical element as well as to operate as a detector show great promise for future chip integration of dual-comb systems.

Published
2015

8. On-chip Dual-comb based on Quantum Cascade Laser Frequency Combs

Author

Villares, Gustavo, Wolf, Johanna, Kazakov, Dmitry, Süess, Martin J, Hugi, Andreas, Beck, Mattias, and Faist, Jérôme

Subjects
Physics - Optics
Abstract

Dual-comb spectroscopy is emerging as one of the most appealing applications of mid-infrared frequency combs for high-resolution molecular spectroscopy, as it leverages on the unique coherence properties of frequency combs combined with the high sensitivities achievable by mid-infrared molecular spectroscopy. Here we present an on-chip dual-comb source based on mid-infrared quantum cascade laser frequency combs, where two frequency combs are integrated on a single chip. Control of the combs repetition and offset frequencies is obtained by integrating micro-heaters next to each laser. We show that a full control of the dual-comb system is possible, by measuring a multi-heterodyne beating corresponding to an optical bandwidth of 32 cm$^{-1}$ at a center frequency of 1330 cm$^{-1}$ (7.52 $\mu$m), demonstrating that this device is ideal for compact dual-comb spectroscopy systems.

Published
2015
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9. Coherent Frequency Combs produced by Self Frequency Modulation in Quantum Cascade Lasers

Author

Khurgin, Jacob, Dikmelik, Yamac, Hugi, Andreas, and Faist, Jerome

Subjects
Physics - Optics
Abstract

One salient characteristic of Quantum Cascade Laser (QCL) is its very shor gain recovery time that so far thwarted the attempts to achieve self-mode locking of the device into a train of single pulses. We show theoretically that four wave mixing, combined with the short gain recovery time causes QCL to operate in the self-frequency-modulated regime characterized by a constant power in time domain and stable coherent comb in the frequency domain.Coherent frequency comb may enable many potential applications of QCL in sensing and measurement.

Published
2013
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11. Mid-infrared dual-comb spectroscopy with quantum cascade lasers.

Author

Hayden, Jakob, Geiser, Markus, Gianella, Michele, Horvath, Raphael, Hugi, Andreas, Sterczewski, Lukasz, and Mangold, Markus

Subjects
MID-infrared spectroscopy, QUANTUM cascade lasers, LIGHT sources, COLD gases
Abstract

Since its invention in 1994, the quantum cascade laser (QCL) has emerged as a versatile light source of wavelength 4–12 µm, covering most of the mid- and long-wavelength infrared spectral ranges. Its application range has widened even further since frequency comb operation and its use as a light source for dual-comb spectroscopy (DCS) was demonstrated. In this tutorial, we introduce the unique properties of QCL frequency combs, such as high optical power, multi-GHz repetition rate, and narrow optical linewidths. Implemented in a dual-comb spectroscopy setup, this allows for broadband, low-noise measurements of strongly absorbing samples with sub-microsecond time resolution, and spectral resolution better than 10−3 cm−1/30 MHz. The advantages of QCL DCS will be discussed in the context of its broad range of applications. The high optical power (both total and per comb tooth) is leveraged for measurements in aqueous solution or at large stand-off distances. Microsecond temporal resolution measurements address the demand for probing rapid protein dynamics and combustion diagnostics. MHz-level spectral resolution, in turn, facilitates accurate line parameter studies in low pressure and cold molecular gases. Future development directions of the technology are discussed, including sub-microsecond response DCS, instrument miniaturization, or its expansion toward THz frequencies. Overall, the tutorial aims at giving a broad introduction to QCL DCS and its applications. [ABSTRACT FROM AUTHOR]

Published
2024
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12. A multiplex inhalation platform to model in situ like aerosol delivery in a breathing lung-on-chip

Author

Sengupta, Arunima, primary, Dorn, Aurélien, additional, Jamshidi, Mohammad, additional, Schwob, Magali, additional, Hassan, Widad, additional, De Maddalena, Lea Lara, additional, Hugi, Andreas, additional, Stucki, Andreas O., additional, Dorn, Patrick, additional, Marti, Thomas M., additional, Wisser, Oliver, additional, Stucki, Janick D., additional, Krebs, Tobias, additional, Hobi, Nina, additional, and Guenat, Olivier T., additional

Published
2023
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14. Quantum Cascade Laser Frequency Combs

Author

Faist Jérôme, Villares Gustavo, Scalari Giacomo, Rösch Markus, Bonzon Christopher, Hugi Andreas, and Beck Mattias

Subjects
spectroscopy, mid-infrared, dual-comb, multiheterodyne, Physics, QC1-999
Abstract

It 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.

Published
2016
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15. A multiplex inhalation platform to model in situ like aerosol delivery in a breathing lung-on-chip

Author

Sengupta, Arunima, Dorn, Aurélien, Jamshidi, Mohammad, Schwob, Magali, Hassan, Widad, De Maddalena, Lea Lara, Hugi, Andreas, Stucki, Andreas O., Dorn, Patrick, Marti, Thomas M., Wisser, Oliver, Stucki, Janick D., Krebs, Tobias, Hobi, Nina, and Guenat, Olivier T.

Subjects
Pharmacology, 570 Life sciences, biology, 610 Medicine & health, Pharmacology (medical)
Abstract

Prolonged exposure to environmental respirable toxicants can lead to the development and worsening of severe respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and fibrosis. The limited number of FDA-approved inhaled drugs for these serious lung conditions has led to a shift from in vivo towards the use of alternative in vitro human-relevant models to better predict the toxicity of inhaled particles in preclinical research. While there are several inhalation exposure models for the upper airways, the fragile and dynamic nature of the alveolar microenvironment has limited the development of reproducible exposure models for the distal lung. Here, we present a mechanistic approach using a new generation of exposure systems, the Cloud α AX12. This novel in vitro inhalation tool consists of a cloud-based exposure chamber (VITROCELL) that integrates the breathing AXLung-on-chip system (AlveoliX). The ultrathin and porous membrane of the AX12 plate was used to create a complex multicellular model that enables key physiological culture conditions: the air-liquid interface (ALI) and the three-dimensional cyclic stretch (CS). Human-relevant cellular models were established for a) the distal alveolar-capillary interface using primary cell-derived immortalized alveolar epithelial cells (AXiAECs), macrophages (THP-1) and endothelial (HLMVEC) cells, and b) the upper-airways using Calu3 cells. Primary human alveolar epithelial cells (AXhAEpCs) were used to validate the toxicity results obtained from the immortalized cell lines. To mimic in vivo relevant aerosol exposures with the Cloud α AX12, three different models were established using: a) titanium dioxide (TiO2) and zinc oxide nanoparticles b) polyhexamethylene guanidine a toxic chemical and c) an anti-inflammatory inhaled corticosteroid, fluticasone propionate (FL). Our results suggest an important synergistic effect on the air-blood barrier sensitivity, cytotoxicity and inflammation, when air-liquid interface and cyclic stretch culture conditions are combined. To the best of our knowledge, this is the first time that an in vitro inhalation exposure system for the distal lung has been described with a breathing lung-on-chip technology. The Cloud α AX12 model thus represents a state-of-the-art pre-clinical tool to study inhalation toxicity risks, drug safety and efficacy.

Published
2023
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21. Mid-infrared frequency comb based on a quantum cascade laser

Author

Hugi, Andreas, Villares, Gustavo, Blaser, Stephane, Liu, H.C., and Faist, Jerome

Subjects
Quantum chemistry -- Research, Infrared spectroscopy -- Research, Lasers -- Properties -- Usage, Laser, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Optical frequency combs (1) act as rulers in the frequency domain and have opened new avenues in many fields such as fundamental time metrology, spectroscopy and frequency synthesis. In particular, [...]

Published
2012
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23. TOWARDS REAL-TIME PROCESSING OF DUAL-COMB SPECTROSCOPY DATA WITH QUANTUM CASCADE LASERS

Author

Gianella, Michele, primary, Emmenegger, Lukas, additional, Faist, Jérôme, additional, Beck, Mattias, additional, Hillbrand, Johannes, additional, Kapsalidis, Filippos, additional, Jouy, Pierre, additional, Mangold, Markus, additional, Hugi, Andreas, additional, Südmeyer, Thomas, additional, Schilt, Stéphane, additional, Komagata, Kenichi, additional, Nataraj, Akshay, additional, Tuzson, Béla, additional, and Vogel, Simon, additional

Published
2021
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24. Gapless high-resolution QCL dual-comb spectroscopy with real-time data processing for dynamic gas-phase measurements

Author

Gianella, Michele, primary, Vogel, Simon, additional, Komagata, Kenichi, additional, Hillbrand, Johannes, additional, Kapsalidis, Filippos, additional, Tuzson, Bela, additional, Nataraj, Akshay, additional, Beck, Mattias, additional, Hugi, Andreas, additional, Mangold, Markus, additional, Jouy, Pierre, additional, Sudmeyer, Thomas, additional, Faist, Jerome, additional, and Emmenegger, Lukas, additional

Published
2021
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25. Frequency noise correlation between the offset frequency and the mode spacing in a mid-infrared quantum cascade laser frequency comb

Author

Shehzad, Atif, Brochard, Pierre, Matthey, Renaud, Kapsalidis, Filippos, Shahmohammadi, Mehran, Beck, Mattias, Hugi, Andreas, Jouy, Pierre, Faist, Jérôme, Südmeyer, Thomas, and Schilt, Stéphane

Subjects
Physics::Optics, Physics::Atomic Physics
Abstract

The generation of frequency combs in the mid-infrared (MIR) spectral range by quantum cascade lasers (QCLs) has the potential for revolutionizing dual-comb multi-heterodyne spectroscopy in the molecular fingerprint region. However, in contrast to frequency combs based on passively mode-locked ultrafast lasers, their operation relies on a completely different mechanism resulting from a four-wave mixing process occurring in the semiconductor gain medium that locks the modes together. As a result, these lasers do not emit pulses and no direct self-referencing of a QCL comb spectrum has been achieved so far. Here, we present a detailed frequency noise characterization of a MIR QCL frequency comb operating at a wavelength of 8 μm with a mode spacing of ~ 7.4 GHz. Using a beat measurement with a narrow-linewidth single-mode QCL in combination with a dedicated electrical scheme, we measured the frequency noise properties of an optical mode of the QCL comb, and indirectly of its offset frequency for the first time, without detecting it by the standard approach of nonlinear interferometry applied to ultrafast mode-locked lasers. In addition, we also separately measured the noise of the comb mode spacing extracted electrically from the QCL. We observed a strong anti-correlation between the frequency fluctuations of the offset frequency and mode spacing, leading to optical modes with a linewidth slightly below 1 MHz in the free-running QCL comb (at 1-s integration time), which is narrower than the individual contributions of the offset frequency and mode spacing that are at least 2 MHz each.

Published
2020

29. Frequency noise correlation between the offset frequency and the mode spacing in a mid-infrared quantum cascade laser frequency comb

Author

Shehzad, Atif, primary, Brochard, Pierre, additional, Matthey, Renaud, additional, Kapsalidis, Filippos, additional, Shahmohammadi, Mehran, additional, Beck, Mattias, additional, Hugi, Andreas, additional, Jouy, Pierre, additional, Faist, Jérôme, additional, Südmeyer, Thomas, additional, and Schilt, Stéphane, additional

Published
2020
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31. Noise Correlation Between the Two Degrees of Freedom of a Mid-Infrared Quantum Cascade Laser Frequency Comb

Author

Shehzad, Atif, primary, Brochard, Pierre, additional, Komagata, Kenichi, additional, Matthey, Renaud, additional, Kapsalidis, Filippos, additional, Shahmohammadi, Mehran, additional, Beck, Mattias, additional, Hugi, Andreas, additional, Jouy, Pierre, additional, Faist, Jérôme, additional, Südmeyer, Thomas, additional, and Schilt, Stéphane, additional

Published
2020
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