| 1. |
- Abd Alrahman, Chadi, et al.
(författare)
-
Cavity-enhanced optical frequency comb spectroscopy of high-temperature H2O in a flame
- 2014
-
Ingår i: Optics Express. - 1094-4087. ; 22:11, s. 13889-13895
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate near-infrared cavity-enhanced optical frequency comb spectroscopy of water in a premixed methane/air flat flame. The detection system is based on an Er:fiber femtosecond laser, a high finesse optical cavity containing the flame, and a fast-scanning Fourier transform spectrometer (FTS). High absorption sensitivity is obtained by the combination of a high-bandwidth two-point comb-cavity lock and auto-balanced detection in the FTS. The system allows recording high-temperature water absorption spectra with a resolution of 1 GHz and a bandwidth of 50 nm in an acquisition time of 0.4 s, with absorption sensitivity of 4.2 x 10 (9) cm(-1) Hz(-1/2) per spectral element.
|
|
| 2. |
- Foltynowicz, Aleksandra, 1981-, et al.
(författare)
-
Broadband molecular detection with cavity-enhanced optical frequency comb spectroscopy
- 2014
-
Ingår i: Optical instrumentation for energy and environmental applications, E2 2014. - Washington, D.C. : Optical Society of America (OSA). - 9781557527561
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate detection of atmospheric species in air and combustion environment using near-infrared cavity-enhanced optical frequency comb spectroscopy based on an Er:fiber femtosecond laser and a fast-scanning Fourier transform spectrometer.
|
|
| 3. |
- Foltynowicz, Aleksandra, 1981-, et al.
(författare)
-
Cavity-enhanced optical frequency combs spectroscopy in the near- and mid-infrared
- 2016
-
Ingår i: Imaging and applied optics 2016. - : OSA - The Optical Society. - 9781943580156
-
Konferensbidrag (refereegranskat)abstract
- We present the recent developments in high-resolution Fourier transform spectroscopy based on optical frequency combs for precision measurements and combustion diagnostics, and the first implementation of continuous-filtering Vernier spectroscopy in the mid-infrared wavelength range for fast multispecies detection.
|
|
| 4. |
- Henderson, Ben, et al.
(författare)
-
Laser spectroscopy for breath analysis : towards clinical implementation
- 2018
-
Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Berlin/Heidelberg. - 0946-2171 .- 1432-0649. ; 124:8
-
Tidskriftsartikel (refereegranskat)abstract
- Detection and analysis of volatile compounds in exhaled breath represents an attractive tool for monitoring the metabolic status of a patient and disease diagnosis, since it is non-invasive and fast. Numerous studies have already demonstrated the benefit of breath analysis in clinical settings/applications and encouraged multidisciplinary research to reveal new insights regarding the origins, pathways, and pathophysiological roles of breath components. Many breath analysis methods are currently available to help explore these directions, ranging from mass spectrometry to laser-based spectroscopy and sensor arrays. This review presents an update of the current status of optical methods, using near and mid-infrared sources, for clinical breath gas analysis over the last decade and describes recent technological developments and their applications. The review includes: tunable diode laser absorption spectroscopy, cavity ring-down spectroscopy, integrated cavity output spectroscopy, cavity-enhanced absorption spectroscopy, photoacoustic spectroscopy, quartz-enhanced photoacoustic spectroscopy, and optical frequency comb spectroscopy. A SWOT analysis (strengths, weaknesses, opportunities, and threats) is presented that describes the laser-based techniques within the clinical framework of breath research and their appealing features for clinical use.
|
|
| 5. |
- Johansson, Alexandra C., et al.
(författare)
-
Faraday rotation spectroscopy using an optical frequency comb
- 2017
-
Ingår i: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). - : IEEE. - 9781509067367
-
Konferensbidrag (refereegranskat)abstract
- Summary form only given. The mid-infrared (MIR) part of the optical spectrum (3-12 μm) houses the fundamental absorption bands of a multitude of environmentally important molecules, but the abundance of water absorption often causes interference with the target species and makes concentration measurement inaccurate. The broad spectral coverage of optical frequency comb spectroscopy (OFCS) provides access to entire ro-vibrational bands and allows more accurate concentration quantification and retrieval of sample temperature. To further improve detection sensitivity of paramagnetic species in the presence of interfering species, we combine a MIR optical frequency comb with the Faraday rotation spectroscopy (FRS) technique [I], which is insensitive to interferences from diamagnetic molecules, such as H 2 O, CO 2 , and CO. In FRS, the rotation of the polarization induced by an external magnetic field in the vicinity of paramagnetic molecular transitions is translated to an intensity change by the use of a polarization analyzer, which effectively removes the influence of any non-paramagnetic species. In the proof of principle demonstration of OFC-FRS we detect nitric oxide (NO) in the presence of water at 5.3 μm using a Fourier transform spectrometer.
|
|
| 6. |
- Johansson, Alexandra C., 1987-, et al.
(författare)
-
Fourier-transform-based noise-immune cavity-enhanced optical frequency comb spectroscopy
- 2016
-
Ingår i: Light, Energy and the Environment. - : Optica Publishing Group (formerly OSA). - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We describe the principles and implementation of Fourier-transform-based cavityenhanced optical frequency comb spectroscopy that uses phase modulation at the cavity free spectral range frequency to achieve high sensitivity over broad spectral range.
|
|
| 7. |
- Johansson, Alexandra C., et al.
(författare)
-
Signal line shapes of Fourier-transform cavity-enhanced frequency modulation spectroscopy with optical frequency combs
- 2017
-
Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 34:2, s. 358-365
-
Tidskriftsartikel (refereegranskat)abstract
- We present a thorough analysis of the signal line shapes of Fourier-transform-based noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS). We discuss the signal dependence on the ratio of the modulation frequency, f(m), to the molecular linewidth, G. We compare a full model of the signals and a simplified absorption-like analytical model that has high accuracy for low f(m)/G ratios and is much faster to compute. We verify the theory experimentally by measuring and fitting the NICE-OFCS spectra of CO2 at 1575 nm using a system based on an Er: fiber femtosecond laser and a cavity with a finesse of similar to 11000.
|
|
| 8. |
- Khodabakhsh, Amir, et al.
(författare)
-
Cavity-Enhanced Continuous-Filtering Vernier Spectroscopy at 3.3 mu m using a Femtosecond Optical Parametric Oscillator
- 2017
-
Ingår i: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC). - : IEEE. - 9781509067367 ; , s. CH_2_2-
-
Konferensbidrag (refereegranskat)abstract
- Optical frequency comb spectroscopy in the mid-infrared fingerprint region combines broad spectral bandwidth with high detection sensitivity and allows simultaneous detection of trace amounts of many molecular species. We have recently demonstrated a continuous-filtering Vernier spectrometer based on a mid-infrared optical frequency comb and an enhancement cavity for fast and sensitive detection of CH4 [1]. Here we present an improved, fully automatized and frequency calibrated continuous-filtering Vernier spectrometer, schematically shown in Fig. 1(a). The comb source is a doubly resonant optical parametric oscillator (DROPO) based on an orientation-patterned GaAs crystal synchronously pumped by a Tm:fiber femtosecond laser (125 MHz repetition rate, frep). The signal comb (3.1–3.4 µm, 30 mW) is mode matched to a 60-cm long Vernier enhancement cavity with a finesse of ~350 at 3.25 μm, placed in an enclosure that can be filled with the gas sample. The output mirror is attached to a PZT and mounted on a translation stage. When the cavity free spectral range is perfectly matched to twice the frep (250 MHz) every other signal comb mode is transmitted through the cavity. By detuning the cavity length from this perfect match position the cavity resonances act as a filter and transmit groups of comb modes called Vernier orders [2]. A diffraction grating mounted on a galvo-scanner separates these orders after the cavity and the chosen order is sent to the detection system. The Vernier order is tuned across the signal comb spectrum by scanning the cavity length (at 20 Hz) and the grating is rotated synchronously to fix the order in space and allow acquisition of the entire spectrum in 25 ms. Any residual mismatch between the cavity length scan and the grating rotation is compensated by a feedback loop acting on the frep of the pump laser and the PZT of the Vernier cavity [2]. A Fabry-Perot etalon is used for frequency calibration of the spectrometer. Figure 1(b) shows in black the normalized transmission spectrum of a sample containing 5.0 ppm CH4 and 160 ppm water. The red and blue curves show the corresponding fit of the Vernier spectrum [3] of CH4 and water, respectively, calculated using Voigt profiles, line parameters from the HITRAN database, and the experimentally determined cavity finesse. The figure of merit of the spectrometer is 1×10−9cm−1 Hz−1∕2 per spectral element and multiline fitting yields minimum detectable concentration of CH4 of 2 ppb in 25 ms, translating into 400 ppt Hz−1∕2 Since the spectrum of the signal comb covers the fundamental C-H stretch transitions we expect low detection limits for other hydrocarbons as well. In conclusion, mid-infrared comb-based continuous-filtering Vernier spectroscopy allows fast and highly sensitive measurement of broadband absorption spectra using a robust and compact detection system.
|
|
| 9. |
|
|
| 10. |
- Khodabakhsh, Amir, et al.
(författare)
-
Cavity-Enhanced Optical Frequency Comb Spectroscopy of High-Temperature Water in a Flame
- 2015
-
Ingår i: 2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO). - 9781557529688
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate detection of broadband high-temperature water spectra in a laminar, premixed methane/air flat flame using high-resolution near-infrared cavity-enhanced optical frequency comb spectroscopy incorporating a fast-scanning Fourier transform spectrometer.
|
|
