scholarly journals Mid-infrared feed-forward dual-comb spectroscopy

2019 ◽  
Vol 116 (9) ◽  
pp. 3454-3459 ◽  
Author(s):  
Zaijun Chen ◽  
Theodor W. Hänsch ◽  
Nathalie Picqué
Keyword(s):  
Molecular Spectroscopy ◽  
Signal To Noise Ratio ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Mid Infrared ◽  
Frequency Combs ◽  
Line Shapes ◽  
Frequency Scale ◽  
Invaluable Tool ◽  
Spectral Profiles

Mid-infrared high-resolution spectroscopy has proven an invaluable tool for the study of the structure and dynamics of molecules in the gas phase. The advent of frequency combs advances the frontiers of precise molecular spectroscopy. Here we demonstrate, in the important 3-µm spectral region of the fundamental CH stretch in molecules, dual-comb spectroscopy with experimental coherence times between the combs that exceed half an hour. Mid-infrared Fourier transform spectroscopy using two frequency combs with self-calibration of the frequency scale, negligible contribution of the instrumental line shape to the spectral profiles, high signal-to-noise ratio, and broad spectral bandwidth opens up opportunities for precision spectroscopy of small molecules. Highly multiplexed metrology of line shapes may be envisioned.

Mid-infrared optical parametric oscillators and frequency combs for molecular spectroscopy

2016 ◽  
Vol 18 (6) ◽  
pp. 4266-4294 ◽  
Author(s):  
M. Vainio ◽  
L. Halonen
Keyword(s):  
Molecular Spectroscopy ◽  
Gas Detection ◽  
High Resolution Spectroscopy ◽  
Trace Gas ◽  
Optical Parametric Oscillators ◽  
Mid Infrared ◽  
Frequency Combs ◽  
Parametric Oscillators ◽  
Optical Parametric ◽  
Fundamental Research

Review of mid-infrared optical parametric oscillators and frequency combs for high-resolution spectroscopy, including applications in trace gas detection and fundamental research.

scholarly journals Mid-infrared photoacoustic gas monitoring driven by a gas-filled hollow-core fiber laser

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yazhou Wang ◽  
Yuyang Feng ◽  
Abubakar I. Adamu ◽  
Manoj K. Dasa ◽  
J. E. Antonio-Lopez ◽  
...  
Keyword(s):  
Fiber Laser ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Laser Source ◽  
High Signal ◽  
Mid Infrared ◽  
Raman Fiber Laser ◽  
Custom Made ◽  
Core Fiber ◽  
Detection Technologies

AbstractDevelopment of novel mid-infrared (MIR) lasers could ultimately boost emerging detection technologies towards innovative spectroscopic and imaging solutions. Photoacoustic (PA) modality has been heralded for years as one of the most powerful detection tools enabling high signal-to-noise ratio analysis. Here, we demonstrate a novel, compact and sensitive MIR-PA system for carbon dioxide (CO2) monitoring at its strongest absorption band by combining a gas-filled fiber laser and PA technology. Specifically, the PA signals were excited by a custom-made hydrogen (H2) based MIR Raman fiber laser source with a pulse energy of ⁓ 18 μJ, quantum efficiency of ⁓ 80% and peak power of ⁓ 3.9 kW. A CO2 detection limit of 605 ppbv was attained from the Allan deviation. This work constitutes an alternative method for advanced high-sensitivity gas detection.

scholarly journals High Signal-to-Noise Ratio Mid-Infrared Quasar Spectral Templates

2013 ◽  
Vol 9 (S304) ◽  
pp. 315-318
Author(s):  
Allison R. Hill ◽  
S. C. Gallagher ◽  
R. P. Deo ◽  
E. Peeters ◽  
Gordon T. Richards
Keyword(s):  
Star Formation ◽  
Signal To Noise Ratio ◽  
Host Galaxy ◽  
High Signal ◽  
Host Galaxies ◽  
Signal To Noise ◽  
Mid Infrared ◽  
High Ionization ◽  
Noise Ratio ◽  
Luminous Objects

AbstractMid-infrared (MIR) quasar spectra exhibit a suite of emission features including high ionization coronal lines from the narrow line region (NLR) illuminated by the ionizing continuum, and hot dust features from grains, as well as polycyclic aromatic hydrocarbons (PAH) features from star formation in the host galaxy. Few features are detected in most spectra because of typically low signal-to-noise ratio (S/N) data. By generating spectral composites in three different luminosity bins from over 180 Spitzer Ifnfrared Spectrograph (IRS) observations, we boost the S/N and reveal important features in the complex spectra. We detect high-ionization, forbidden emission lines in all templates, PAH features in all but the most luminous objects, and broad silicate and graphite features in emission whose strength increases relative to the continuum with luminosity. We find that the intrinsic quasar spectrum for all luminosity templates is consistent, and the differences in the spectra can be explained by host galaxy contamination in the lower luminosity templates. We also posit that star formation may be active in most quasar host galaxies, but the spectral features of star formation are only detectable if the quasar is faint.

scholarly journals Broadband high-resolution molecular spectroscopy with interleaved mid-infrared frequency combs

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
A. V. Muraviev ◽  
D. Konnov ◽  
K. L. Vodopyanov
Keyword(s):  
High Resolution ◽  
Molecular Spectroscopy ◽  
Frequency Comb ◽  
Acquisition Time ◽  
Sampling Point ◽  
Dual Frequency ◽  
Mid Infrared ◽  
Frequency Combs ◽  
Spectral Bands ◽  
Primary Frequency

Abstract Traditionally, there has been a trade-off in spectroscopic measurements between high resolution, broadband coverage, and acquisition time. Originally envisioned for precision spectroscopy of the hydrogen atom in the ultraviolet, optical frequency combs are now commonly used for probing molecular ro-vibrational transitions throughout broad spectral bands in the mid-infrared providing superior resolution, speed, and the capability of referencing to the primary frequency standards. Here we demonstrate the acquisition of 2.5 million spectral data points over the continuous wavelength range of 3.17–5.13 µm (frequency span 1200 cm−1, sampling point spacing 13–21 MHz), via interleaving comb-tooth-resolved spectra acquired with a highly-coherent broadband dual-frequency-comb system based on optical subharmonic generation. With the original comb-line spacing of 115 MHz, overlaying eight spectra with gradually shifted comb lines we fully resolve the amplitude and phase spectra of molecules with narrow Doppler lines, such as carbon disulfide (CS2) and its three isotopologues.

scholarly journals Recent Helioseismological Results from Space: Solar p-mode Oscillations from IPHIR on the PHOBOS Mission

1990 ◽  
Vol 121 ◽  
pp. 279-288
Author(s):  
C. Fröhlich ◽  
T. Toutain ◽  
R.M. Bonnet ◽  
A.V. Bruns ◽  
J.P. Delaboudinière ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Spectral Irradiance ◽  
High Signal ◽  
Line Shapes ◽  
Solar Spectral Irradiance ◽  
Evaluation Of Data ◽  
Very High ◽  
Better Than

AbstractIPHIR (Interplanetary Helioseismology by IRradiance measurements) is a solar irradiance experiment on the USSR planetary mission PHOBOS to Mars and its satellite Phobos. The experiment was built by an international consortium including PMOD/WRC, LPSP, SSD/ESA, KrAO and CRIP. The sensor is a three channel sunphotometer (SPM) which measures the solar spectral irradiance at 335, 500 and 865 nm with a precision of better than 1 part-per-million (ppm). It is the first experiment dedicated to the investigation of solar oscillations from space. The results presented here are from a first evaluation of data gathered during 160 days of the cruise phase of PHOBOS II, launched on July, 12th 1988. The long uninterrupted observation produces a spectrum of the solar p-mode oscillations in the 5-minute range with a very high signal-to-noise ratio, which allows an accurate determination of frequencies and line shapes of these modes.

scholarly journals A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808

2019 ◽  
Vol 631 ◽  
pp. A14 ◽  
Author(s):  
M. Latour ◽  
T.-O. Husser ◽  
B. Giesers ◽  
S. Kamann ◽  
F. Göttgens ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Signal To Noise Ratio ◽  
Spectral Lines ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Multiple Populations ◽  
Synthetic Populations ◽  
Central Regions ◽  
Chromosome Maps ◽  
Red Giant

Context. Galactic globular clusters (GCs) are now known to host multiple populations displaying particular abundance variations. The different populations within a GC can be well distinguished following their position in the pseudo two-colors diagrams, also referred to as “chromosome maps”. These maps are constructed using optical and near-UV photometry available from the Hubble Space Telescope (HST) UV survey of GCs. However, the chemical tagging of the various populations in the chromosome maps is hampered by the fact that HST photometry and elemental abundances are both only available for a limited number of stars. Aims. The spectra collected as part of the MUSE survey of globular clusters provide a spectroscopic counterpart to the HST photometric catalogs covering the central regions of GCs. In this paper, we use the MUSE spectra of 1115 red giant branch (RGB) stars in NGC 2808 to characterize the abundance variations seen in the multiple populations of this cluster. Methods. We used the chromosome map of NGC 2808 to divide the RGB stars into their respective populations. We then combined the spectra of all stars belonging to a given population, resulting in one high signal-to-noise ratio spectrum representative of each population. Results. Variations in the spectral lines of O, Na, Mg, and Al are clearly detected among four of the populations. In order to quantify these variations, we measured equivalent width differences and created synthetic populations spectra that were used to determine abundance variations with respect to the primordial population of the cluster. Our results are in good agreement with the values expected from previous studies based on high-resolution spectroscopy. We do not see any significant variations in the spectral lines of Ca, K, and Ba. We also do not detect abundance variations among the stars belonging to the primordial population of NGC 2808. Conclusions. We demonstrate that in spite of their low resolution, the MUSE spectra can be used to investigate abundance variations in the context of multiple populations.

scholarly journals Nonradial pulsations in the open cluster NGC 3766

2009 ◽  
Vol 5 (S266) ◽  
pp. 518-521
Author(s):  
Rachael M. Roettenbacher ◽  
Ernest C. Amouzou ◽  
M. Virginia McSwain
Keyword(s):  
Signal To Noise Ratio ◽  
Large Fraction ◽  
Open Cluster ◽  
Spectroscopic Studies ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Be Stars ◽  
B Stars ◽  
Be Star ◽  
Large Telescopes

AbstractNonradial pulsations (NRPs) are a proposed mechanism for the formation of decretion disks around Be stars. They are important tools to study the internal structure of stars. NGC 3766 has an unusually large fraction of transient Be stars, so it is an excellent location to study the formation mechanism of Be-star disks. High-resolution spectroscopy can reveal line-profile variations from NRPs, allowing measurements of both the degree, l, and azimuthal order, m. However, spectroscopic studies require large amounts of time with large telescopes to achieve the necessary high signal-to-noise ratio and time-domain coverage. On the other hand, multicolor photometry can be performed more easily with small telescopes to measure l only. Here, we present representative light curves of Be stars and nonemitting B stars in NGC 3766 from the CTIO 0.9m telescope in an effort to study NRPs in this cluster.

scholarly journals Application of High-Speed Quantum Cascade Detectors for Mid-Infrared, Broadband, High-Resolution Spectroscopy

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5706
Author(s):  
Tatsuo Dougakiuchi ◽  
Naota Akikusa
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Dynamic Range ◽  
Molecular Spectroscopy ◽  
Low Noise ◽  
Heterodyne Detection ◽  
High Resolution Spectroscopy ◽  
Mid Infrared ◽  
Quantum Cascade ◽  
Noise Characteristics

Broadband, high-resolution, heterodyne, mid-infrared absorption spectroscopy was performed with a high-speed quantum cascade (QC) detector. By strictly reducing the device capacitance and inductance via air-bridge wiring and a small mesa structure, a 3-dB frequency response over 20 GHz was obtained for the QC detector, which had a 4.6-μm peak wavelength response. In addition to the high-speed, it exhibited low noise characteristics limited only by Johnson–Nyquist noise, bias-free operation without cooling, and photoresponse linearity over a wide dynamic range. In the detector characterization, the noise-equivalent power was 7.7 × 10−11 W/Hz1/2 at 4.6 μm, and it had good photoresponse linearity up to 250 mW, with respect to the input light power. Broadband and high-accuracy molecular spectroscopy based on heterodyne detection was demonstrated by means of two distributed-feedback 4.5-μm QC lasers. Specifically, several nitrous oxide absorption lines were acquired over a wavelength range of 0.8 cm−1 with the wide-band QC detector.

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