| 1. |
- Foltynowicz, Aleksandra, 1981-, et al.
(författare)
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Measurement and assignment of double-resonance transitions to the 8900-9100- cm-1 levels of methane
- 2021
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 103:2
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Tidskriftsartikel (refereegranskat)abstract
- Optical-optical double-resonance spectroscopy with a continuous wave pump and frequency comb probe allows measurement of sub-Doppler transitions to highly excited molecular states over a wide spectral range with high frequency accuracy. We report on assessment and characterization of sub-Doppler double-resonance transitions in methane measured using a 3.3-μm continuous wave optical parametric oscillator as a pump and a 1.67-μm frequency comb as a probe. The comb spectra were recorded using a Fourier transform spectrometer with comb-mode-limited resolution. With the pump tuned to nine different transitions in the ν3 fundamental band, we detected 36 ladder-type transitions to the 3ν3 overtone band region, and 18 V-type transitions to the 2ν3 overtone band. We describe in detail the experimental approach and the pump stabilization scheme, which currently limits the frequency accuracy of the measurement. We present the data analysis procedure used to extract the frequencies and intensities of the probe transitions for parallel and perpendicular relative pump-probe polarization. We compare the center frequencies and relative intensities of the ladder-type transitions to theoretical predictions from the TheoReTS and ExoMol line lists, demonstrating good agreement with TheoReTS.
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| 2. |
- Foltynowicz, Aleksandra, 1981-, et al.
(författare)
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Sub-Doppler Double-Resonance Spectroscopy of Methane Using a Frequency Comb Probe
- 2021
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 126:6
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurement of sub-Doppler molecular response using a frequency comb by employing the comb as a probe in optical-optical double-resonance spectroscopy. We use a 3.3 μm continuous wave pump and a 1.67 μm comb probe to detect sub-Doppler transitions to the 2ν3 and 3ν3 bands of methane with ∼1.7 MHz center frequency accuracy. These measurements provide the first verification of the accuracy of theoretical predictions from highly vibrationally excited states, needed to model the high-temperature spectra of exoplanets. Transition frequencies to the 3ν3 band show good agreement with the TheoReTS line list.
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| 3. |
- Foltynowicz, Aleksandra, 1981-, et al.
(författare)
-
Sub-doppler double-resonance spectroscopy of methane using a frequency comb probe
- 2020
-
Ingår i: Conference on Lasers and Electro-Optics. - : Optica Publishing Group (formerly OSA). - 9781943580767 - 9781728144184
-
Konferensbidrag (refereegranskat)abstract
- We use a 3.3 µm continuous wave optical parametric oscillator as a pump and a 1.67 µm frequency comb as a probe to record 36 sub-Doppler double-resonance transitions in the 3v3 band of methane (including 26 previously unreported) with ~1.5 MHz center frequency accuracy.
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| 4. |
- Germann, Matthias, et al.
(författare)
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A methane line list with sub-MHz accuracy in the 1250 to 1380 cm−1 range from optical frequency comb Fourier transform spectroscopy
- 2022
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073 .- 1879-1352. ; 288
-
Tidskriftsartikel (refereegranskat)abstract
- We use a Fourier transform spectrometer based on a difference frequency generation optical frequency comb to measure high-resolution, low-pressure, room-temperature spectra of methane in the 1250 – 1380-cm−1 range. From these spectra, we retrieve line positions and intensities of 678 lines of two isotopologues: 157 lines from the 12CH4 ν4 fundamental band, 131 lines from the 13CH4 ν4 fundamental band, as well as 390 lines from two 12CH4 hot bands, ν2 + ν4 – ν2 and 2ν4 – ν4. For another 165 lines from the 12CH4 ν4 fundamental band we retrieve line positions only. The uncertainties of the line positions range from 0.19 to 2.3 MHz, and their median value is reduced by a factor of 18 and 59 compared to the previously available data for the 12CH4 fundamental and hot bands, respectively, obtained from conventional FTIR absorption measurements. The new line positions are included in the global models of the spectrum of both methane isotopologues, and the fit residuals are reduced by a factor of 8 compared to previous absorption data, and 20 compared to emission data. The experimental line intensities have relative uncertainties in the range of 1.5 – 7.7%, similar to those in the previously available data; 235 new 12CH4 line intensities are included in the global model.
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| 5. |
- Germann, Matthias, et al.
(författare)
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An Accurate Methane Line List in the 7.2-8.0 µm Range from Comb-Based Fourier Transform Spectroscopy
- 2022
-
Ingår i: CLEO: 2022. - : Optica Publishing Group. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We use comb-based Fourier transform spectroscopy to record high-resolution spectra of 12CH4 and 13CH4 from 1250 to 1380 cm-1. We obtain line positions and intensities of 4 bands with uncertainties of ~450 kHz and ~3%, respectively, which we use to improve a global fit of the effective Hamiltonian.
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| 6. |
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| 7. |
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| 8. |
- Germann, Matthias, et al.
(författare)
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Optical frequency comb Fourier transform spectroscopy of formaldehyde in the 1250 to 1390 cm−1 range : experimental line list and improved MARVEL analysis
- 2024
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 312
-
Tidskriftsartikel (refereegranskat)abstract
- We use optical frequency comb Fourier transform spectroscopy to record high-resolution, low-pressure, room-temperature spectra of formaldehyde (H212C16O) in the range of 1250 to 1390 cm−1. Through line-by-line fitting, we retrieve line positions and intensities of 747 rovibrational transitions: 558 from the ν6 band, 129 from the ν4 band, and 14 from the ν3 band, as well as 46 from four different hot bands. We incorporate the accurate and precise line positions (0.4 MHz median uncertainty) into the MARVEL (measured active vibration-rotation energy levels) analysis of the H2CO spectrum. This increases the number of MARVEL-predicted energy levels by 82 and of rovibrational transitions by 5382, and substantially reduces uncertainties of MARVEL-derived H2CO energy levels over a large range: from pure rotational levels below 200 cm−1 up to multiply excited vibrational levels at 6000 cm−1. This work is an important step toward filling the gaps in formaldehyde data in the HITRAN database.
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| 9. |
- Gluszek, Aleksander, et al.
(författare)
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Compact mode-locked Er-doped fiber laser for broadband cavity-enhanced spectroscopy
- 2020
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer. - 0946-2171 .- 1432-0649. ; 126:8
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Tidskriftsartikel (refereegranskat)abstract
- We report the design and characteristics of a simple and compact mode-locked Er-doped fiber laser and its application to broadband cavity-enhanced spectroscopy. The graphene mode-locked polarization maintaining oscillator consumes less than 5 W of power. It is thermally stabilized, enclosed in a 3D printed box, and equipped with three actuators that control the repetition rate: fast and slow fiber stretchers, and metal-coated fiber section. This allows wide tuning of the repetition rate and its stabilization to an external reference source. The applicability of the laser to molecular spectroscopy is demonstrated by detecting CO(2)in air using continuous-filtering Vernier spectroscopy with absorption sensitivity of 5.5 x 10(-8)cm(-1)in 50 ms.
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| 10. |
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| 11. |
- Hjältén, Adrian, 1988-, et al.
(författare)
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Accurate measurement and assignment of high rotational energy levels of the 3v3 ← v3 band of methane
- 2023
-
Ingår i: 2023 conference on lasers and electro-optics, CLEO 2023. - : IEEE. - 9781957171258 - 9781665455688
-
Konferensbidrag (refereegranskat)abstract
- We use optical-optical double-resonance spectroscopy with a high-power continuous wave pump and a cavity-enhanced comb probe to expand sub-Doppler measurements of the 3v3 ← v3 band of CH4 to higher rotational levels. We assign the final states using combination differences, i.e., by reaching the same state using different pump/probe combinations.
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| 12. |
- Hjältén, Adrian, et al.
(författare)
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Fourier transform spectroscopy using difference frequency generation comb sources at 3.3 µm and 7.8 µm
- 2021
-
Ingår i: Proceedings OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES). - : Optical Society of America. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We use offset-frequency-free difference frequency generation comb sources and a Fourier transform spectrometer with comb-mode-width limited resolution to measure and analyze spectra of molecular species of atmospheric relevance: CH3I and CH2Br2 around 3000 cm-1, and 14N216O around 1280 cm-1
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| 13. |
- Hjältén, Adrian, et al.
(författare)
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Optical frequency comb Fourier transform spectroscopy of 14N216O at 7.8 µm
- 2021
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 271
-
Tidskriftsartikel (refereegranskat)abstract
- We use a Fourier transform spectrometer based on a compact mid-infrared difference frequency generation comb source to perform broadband high-resolution measurements of nitrous oxide, 14N216O, and retrieve line center frequencies of the ν1 fundamental band and the ν1 + ν2 – ν2 hot band. The spectrum spans 90 cm−1 around 1285 cm−1 with a sample point spacing of 3 × 10−4 cm−1 (9 MHz). We report line positions of 72 lines in the ν1 fundamental band between P(37) and R(38), and 112 lines in the ν1 + ν2 – ν2 hot band (split into two components with e/f rotationless parity) between P(34) and R(33), with uncertainties in the range of 90-600 kHz. We derive upper state constants of both bands from a fit of the effective ro-vibrational Hamiltonian to the line center positions. For the fundamental band, we observe excellent agreement in the retrieved line positions and upper state constants with those reported in a recent study by AlSaif et al. using a comb-referenced quantum cascade laser [J Quant Spectrosc Radiat Transf, 2018;211:172-178]. We determine the origin of the hot band with precision one order of magnitude better than previous work based on FTIR measurements by Toth [http://mark4sun.jpl.nasa.gov/n2o.html], which is the source of the HITRAN2016 data for these bands.
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| 14. |
- Hjältén, Adrian, et al.
(författare)
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Precision measurements of 14N216O using a comb-based fourier transform spectrometer at 7.8 µm
- 2021
-
Ingår i: CLEO: Science and Innovations. - : Optical Society of America. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- Using a compact fiber-based difference frequency generation comb and a Fourier transform spectrometer we record spectra of the N2O ν1 band at 1285 cm-1 in the Doppler limit. Fitting Gaussian line shapes to the individual absorption lines yields center frequencies with <200 kHz average precision.
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| 15. |
- Khodabakhsh, Amir, et al.
(författare)
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Cavity-Enhanced Continuous-Filtering Vernier Spectroscopy at 3.3 mu m using a Femtosecond Optical Parametric Oscillator
- 2017
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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.
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| 16. |
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| 17. |
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| 18. |
- Krzempek, Karol, et al.
(författare)
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Compact 6.5 – 9 μm frequency comb source for fourier transform spectroscopy
- 2020
-
Ingår i: Optics and Photonics for Sensing the Environment. - : The Optical Society. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a compact fully-stabilized fiber-based optical frequency comb based on difference frequency generation tunable from 6.5 to 9 μm and its application to Fourier transform spectroscopy of nitrous oxide (N2O).
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| 19. |
- Krzempek, Karol, et al.
(författare)
-
Compact fiber-based mid-infrared frequency comb sources
- 2022
-
Ingår i: Optica High-brightness Sources and Light-driven Interactions Congress 2022. - : Optica Publishing Group (formerly OSA). - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We report the development of compact, stabilized fiber-based mid-infrared frequency comb sources covering the 7–9 μm and 3.1–3.4 μm spectral ranges. Both sources enable high-precision Fourier-transform spectroscopy of greenhouse gases.
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| 20. |
- Krzempek, Karol, et al.
(författare)
-
Fiber-based optical frequency comb at 3.3 μm for broadband spectroscopy of hydrocarbons [Invited]
- 2021
-
Ingår i: Chinese Optics Letters (COL). - : The Optical Society. - 1671-7694. ; 19:8
-
Tidskriftsartikel (refereegranskat)abstract
- A 125 MHz fiber-based frequency comb source in the mid-infrared wavelength region is presented. The source is based on difference frequency generation from a polarization-maintaining Er-doped fiber pump laser and covers a spectrum between 2900 cm−1 and 3400 cm−1 with a simultaneous bandwidth of 170 cm−1 and an average output power up to 70 mW. The source is equipped with actuators and active feedback loops, ensuring long-term stability of the repetition rate, output power, and spectral envelope. An absorption spectrum of ethane and methane was measured using a Fourier transform spectrometer to verify the applicability of the mid-infrared comb to multispecies detection. The robustness and good long- and short-term stability of the source make it suitable for optical frequency comb spectroscopy of hydrocarbons.
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| 21. |
- Krzempek, Karol, et al.
(författare)
-
Mid-infrared frequency comb covering the 6.5 – 9 µm range with active output power stabilization
- 2020
-
Ingår i: Proceedings <em>OSA High-brightness Sources and Light-driven Interactions Congress 2020 (EUVXRAY, HILAS, MICS)</em>. - : The Optical Society. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We report a compact, actively stabilized fiber-based mid-infrared frequency comb source covering the 6.5 – 9 µm wavelength range with up to 5 mW of average output power at 125 MHz repetition frequency.
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| 22. |
- Krzempek, Karol, et al.
(författare)
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Stabilized all-fiber source for generation of tunable broadband fCEO-free mid-IR frequency comb in the 7–9 µm range
- 2019
-
Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 27:26, s. 37435-37445
-
Tidskriftsartikel (refereegranskat)abstract
- A compact and robust all-fiber difference frequency generation-based source of broadband mid-infrared radiation is presented. The source emits tunable radiation in the range between 6.5 µm and 9 µm with an average output power up to 5 mW at 125 MHz repetition frequency. The all-in-fiber construction of the source along with active stabilization techniques results in long-term repetition rate stability of 3 Hz per 10 h and a standard deviation of the output power better than 0.8% per 1 h. The applicability of the presented source to laser spectroscopy is demonstrated by measuring the absorption spectrum of nitrous oxide (N2O) around 7.8 µm. The robustness and good long- and short-term stability of the source opens up for applications outside the laboratory.
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| 23. |
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| 24. |
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| 25. |
- Lu, Chuang, et al.
(författare)
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Robust and High-Speed Cavity-Enhanced Vernier Spectrometer
- 2021
-
Ingår i: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021. - : IEEE Lasers and Electro-Optics Society. - 9781665418768
-
Konferensbidrag (refereegranskat)abstract
- Sensitive in situ detection of multiple atmospheric species at fast acquisition rates is needed for environmental monitoring. For field applications, robust and compact design is also demanded. Continuous-filtering Vernier spectroscopy (CF-VS) [1] is a cavity-enhanced frequency-comb-based technique that provides broad spectral bandwidth and high absorption sensitivity in short acquisition times. In CF-VS, groups of comb lines (Vernier orders, VOs) are transmitted through the cavity when its free spectral range (FSR) is slightly detuned from the comb repetition rate ( f rep ) and continuously swept across the broadband laser spectrum (by scanning the FSR). In previous implementations [1] - [3] , a diffraction grating rotating on a galvo scanner was used to image one VO on the detector during the spectral scan, limiting the acquisition rates to 20 Hz. Moreover, high-bandwidth stabilization was needed to synchronize the scans of the galvo and the cavity FSR. Here we present an improved design of CF-VS based on a compact Er:fiber laser and a moving aperture that follows and selects one VO. This removes the requirement of tight active stabilization and enables faster acquisition rates.
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| 26. |
- Lu, Chuang, et al.
(författare)
-
Robust, fast and sensitive near-infrared continuous-filtering Vernier spectrometer
- 2021
-
Ingår i: Optics Express. - : The Optical Society. - 1094-4087. ; 29:19, s. 30155-30167
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new design of a robust cavity-enhanced frequency comb-based spectrometer operating under the continuous-filtering Vernier principle. The spectrometer is based on a compact femtosecond Er-doped fiber laser, a medium finesse cavity, a diffraction grating, a custom-made moving aperture, and two photodetectors. The new design removes the requirement for high-bandwidth active stabilization present in the previous implementations of the technique, and allows scan rates up to 100 Hz. We demonstrate the spectrometer performance over a wide spectral range by detecting CO2 around 1575 nm (1.7 THz bandwidth and 6 GHz resolution) and CH4 around 1650 nm (2.7 THz bandwidth and 13 GHz resolution). We achieve absorption sensitivity of 5 × 10−9 cm-1 Hz-1/2 at 1575 nm, and 1 × 10−7 cm-1 Hz-1/2 cm-1 at 1650 nm. We discuss the influence of the scanning speed above the adiabatic limit on the amplitude of the absorption signal.
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| 27. |
- Rolla, Dorota Tomaszewska, et al.
(författare)
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Mid-infrared optical frequency comb spectroscopy using an all-silica antiresonant hollow-core fiber
- 2024
-
Ingår i: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 32:6, s. 10679-10689
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first mid-infrared optical frequency comb spectrometer employing an absorption cell based on self-fabricated, all-silica antiresonant hollow-core fiber (ARHCF). The spectrometer is capable of measuring sub-mL sample volumes with 26 m interaction length and noise equivalent absorption sensitivity of 8.3 × 10−8 cm−1 Hz−1/2 per spectral element in the range of 2900 cm−1 to 3100 cm−1. Compared to a commercially available multipass cell, the ARHCF offers a similar interaction length in a 1000 times lower gas sample volume and a 2.8 dB lower transmission loss, resulting in better absorption sensitivity. The broad transmission windows of ARHCFs, in combination with a tunable optical frequency comb, make them ideal for multispecies detection, while the prospect of measuring samples in small volumes makes them a competitive technique to photoacoustic spectroscopy along with the robustness and prospect of coiling the ARHCFs open doors for miniaturization and out-of-laboratory applications.
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| 28. |
- Silva de Oliveira, Vinicius, et al.
(författare)
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Double-Resonance Spectroscopy of Methane Using a Comb Probe
- 2021
-
Ingår i: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021. - : IEEE Lasers and Electro-Optics Society. - 9781665418768
-
Konferensbidrag (refereegranskat)abstract
- Optical-optical double resonance (OODR) spectroscopy is a powerful tool for the experimental assignment of highly-excited molecular states, which in turn is needed for verification of the accuracy of theoretical predictions of high-temperature spectra observed in exoplanets and in combustion environments. Previous implementations of OODR used either continuous wave (cw) lasers, which limit the number of transitions that can be detected, or pulsed lasers, which limit the spectral resolution. Recently, we demonstrated OODR with a cw pump and a frequency comb probe and applied it to the detection and assignment of methane transitions in the 3ν 3 ← ν 3 range with sub-Doppler resolution over 200 cm -1 of bandwidth [1]. The pump [see Fig. 1(a) ] was a 1 W 3.3m idler of a cw optical parametric oscillator (cw-OPO), stabilized to the Lamb dip in a selected CH 4 transition in the ν 3 band using a signal from a reference cell. The probe was an amplified fully-stabilized Er:fiber comb ( f rep = 250 MHz), whose center wavelength was shifted to 1.67m using a soliton self-frequency shift fiber (SSSF). The sample of pure CH 4 was contained in an 80-cm-long single-pass cell cooled by liquid nitrogen. The probe spectra were detected using a Fourier transform spectrometer (FTS) with comb-mode-limited resolution [2] , and the final interleaved spectra had 2 MHz sampling point spacing. Figure 1(b) shows the 3ν 3 ← ν 3 R(1) transition at 6046.36008(5) cm -1 , detected with the pump on the ν 3 R(0) line. We measured, fit and assigned 36 probe transitions with the pump tuned to 9 different transitions. Figure 1(d) shows a comparison of the probe transition wavenumbers to predictions from the TheoReTS database [3] , demonstrating agreement within 1 cm -1.
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| 29. |
- Silva de Oliveira, Vinicius, et al.
(författare)
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Measurement and Assignment of Hot-Band Methane Transitions with Sub-MHz Accuracy
- 2022
-
Ingår i: CLEO: 2022. - : Optica Publishing Group. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We use double-resonance spectroscopy with cavity-enhanced comb probe to measure sub-Doppler transitions in the 3ν3←ν3 band of CH4. We assign the final states using different pump/probe combinations reaching the same state, and the dependence of line intensities on relative pump/probe polarization.
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| 30. |
- Silva de Oliveira, Vinicius, et al.
(författare)
-
Optical-optical double-resonance spectroscopy of methane using a cavity-enhanced comb probe
- 2021
-
Ingår i: OSA Technical Digest. - : Optical Society of America. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We implement a cavity to enhance the absorption of a frequency comb probe in a double-resonance measurement of sub-Doppler 3ν3 ← ν3 methane transitions. This yields two orders of magnitude better sensitivity in 15 times shorter acquisition time compared to previous work using a single-pass cell.
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| 31. |
- Silva de Oliveira, Vinicius, et al.
(författare)
-
Sub-doppler optical-optical double-resonance spectroscopy of methane using a frequency comb probe
- 2021
-
Ingår i: OSA Optical Sensors and Sensing Congress 2021 (AIS, FTS, HISE, SENSORS, ES). - : Optical Society of America. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- We use a 3.3 µm high-power continuous wave pump and a 1.67 µm comb probe to detect transitions in the 3ν3 ← ν3 range of methane with sub-Doppler resolution over 6 THz of bandwidth. We achieve high absorption sensitivity for the comb probe using an enhancement cavity and a Fourier transform spectrometer with auto-balanced detection.
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| 32. |
- Silva de Oliveira, Vinicius, et al.
(författare)
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Sub-Doppler optical-optical double-resonance spectroscopy using a cavity-enhanced frequency comb probe
- 2024
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate parameters of molecular hot-band transitions, i.e., those starting from vibrationally excited levels, are needed to accurately model high-temperature spectra in astrophysics and combustion, yet laboratory spectra measured at high temperatures are often unresolved and difficult to assign. Optical-optical double-resonance (OODR) spectroscopy allows the measurement and assignment of individual hot-band transitions from selectively pumped energy levels without the need to heat the sample. However, previous demonstrations lacked either sufficient resolution, spectral coverage, absorption sensitivity, or frequency accuracy. Here we demonstrate OODR spectroscopy using a cavity-enhanced frequency comb probe that combines all these advantages. We detect and assign sub-Doppler transitions in the spectral range of the 3ν3 ← ν3 resonance of methane with frequency precision and sensitivity more than an order of magnitude better than before. This technique will provide high-accuracy data about excited states of a wide range of molecules that is urgently needed for theoretical modeling of high-temperature data and cannot be obtained using other methods.
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| 33. |
- Soboń, Grzegorz, et al.
(författare)
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High-power broadband source tunable from 2.8 to 4 μm based on difference frequency generation
- 2017
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Ingår i: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). - : IEEE. - 9781509067367
-
Konferensbidrag (refereegranskat)abstract
- Mid-infrared (MIR) frequency comb sources enable high-speed and accurate detection of various species, since many molecules possess their fingerprints in this wavelength range. Usually, broadband radiation in this spectral region is obtained from optical parametric oscillators (OPOs), which provide high output power and broad tuning capabilities [1]. However, OPO sources require locking of the cavity to the pumping oscillator, which increases the complexity. MIR sources based on difference frequency generation (DFG) are interesting alternatives to OPOs, due to their simplicity, single-pass configuration, broad tunability, and fully passive cancellation of the carrier-envelope offset in the generated idler pulses. However, the conversion efficiency of the DFG process is usually insufficient to reach the output power levels easily achieved in OPO systems. Here, we demonstrate a widely tunable DFG source based on a mode-locked Yb-doped fiber laser, with average MIR output power reaching 165 mW, which is more than in previous reports on similar DFG systems [2,3].
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| 34. |
- Sobon, Grzegorz, et al.
(författare)
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High-power frequency comb source tunable from 2.7 to 4.2 mu m based on difference frequency generation pumped by an Yb-doped fiber laser
- 2017
-
Ingår i: Optics Letters. - : OPTICAL SOC AMER. - 0146-9592 .- 1539-4794. ; 42:9, s. 1748-1751
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a broadband mid-infrared (MIR) frequency comb source based on difference frequency generation (DFG) in periodically poled lithium niobate crystal. MIR radiation is obtained via mixing of the output of a 125 MHz repetition rate Yb-doped fiber laser with Raman-shifted solitons generated from the same source in a highly nonlinear fiber. The resulting idler is tunable in the range of 2.7-4.2 mu m, with average output power reaching 237 mW and pulses as short as 115 fs. The coherence of the MIR comb is confirmed by spectral interferometry and heterodyne beat measurements. Applicability of the developed DFG source for laser spectroscopy is demonstrated by measuring absorption spectrum of acetylene at 3.0-3.1 mu m. (C) 2017 Optical Society of America
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| 35. |
- Sobon, Grzegorz, et al.
(författare)
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Shot-to-shot performance analysis of an all-fiber supercontinuum source pumped at 2000 nm
- 2018
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 36:2, s. A15-A21
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report an all-fiber supercontinuum source pumped with ultra-short pulses at 1.9–2.0 μm, covering over an octave (1200–2400 nm). We investigated the shot-to-shot stability of the supercontinuum generated in a commercially available highly nonlinear fiber (HNLF) of different lengths, ranging from 5 to 80 cm, by employing the dispersive Fourier transform method. Our study shows that using shorter HNLFs significantly improves the shot-to-shot stability while maintaining the broad spectral coverage. The supercontinuum generated in HNLFs shorter than 10 cm is characterized by excellent stability despite the anomalous-dispersion characteristic of the fiber. The presented source is characterized by exceptional simplicity, showing readiness for outside-of-lab applications.
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| 36. |
- Szewczyk, Olga, et al.
(författare)
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Dual-wavelength pumped highly birefringent microstructured silica fiber for widely tunable soliton self-frequency shift
- 2021
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 39:10, s. 3260-3268
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Tidskriftsartikel (refereegranskat)abstract
- We report the design of a microstructured silica-based fiber for widely tunable soliton self-frequency shift, suitable for pumping with two most common fiber laser wavelengths: 1.04 μm and 1.55 μm. Depending on the pump source, the output spectrum can be continuously tuned up to 1.67 μm (pump at 1.04 μm) or 1.95 μm (pump at 1.55 μm) in the same 1.5 m-long fiber sample, with pump-to-soliton conversion efficiency higher than 20%. The fiber is highly birefringent, which results in an excellent polarization extinction ratio of the soliton, reaching 26 dB. The shifted solitons have a high degree of coherence confirmed by pulse-to-pulse interference measurement. The available soliton tuning range covers the wavelengths inaccessible for fiber lasers, e.g., 1.3 μm and 1.7 μm, highly important for multi-photon microscopy and imaging. Our work shows that it is possible to design and fabricate one universal optical fiber that supports soliton shift when pumped at two different wavelengths separated by over 500 nm.
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| 37. |
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| 38. |
- Tomaszewska-Rolla, Dorota, et al.
(författare)
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A comparative study of an Yb-doped fiber gain-managed nonlinear amplifier seeded by femtosecond fiber lasers
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we show that the nonlinear evolution of femtosecond seed pulses with different parameters (temporal and spectral shapes, repetition rate, pulse energy) in an Yb-fiber amplifier leads to gain-managed nonlinear amplification, enabling robust generation of high-peak-power and nearly transform-limited pulses after external compression. We demonstrate a compressed pulse duration of 33 fs with an energy of 80.5 nJ and a peak power of 2.29 MW for a source with a repetition rate of 30 MHz. For a second seed source with a repetition rate of 125 MHz, we obtained a pulse duration of 51 fs with an energy of 22.8 nJ and a peak power of 420 kW. Numerical simulations incorporating rate equations and nonlinear propagation in the amplifier provide evolutions that agree well with the experimental results. The discrepancies in the amplifier's absorption edge appearing at low repetition rates and higher pump powers are attributed to the temperature dependence of the amplifier's gain cross-sections. Here, we experimentally verify this attribution and thus underline the importance of accounting for the fiber core temperature for precise modelling of the short-wavelength spectral edge of the output pulses in nonlinear Yb-fiber amplifiers. We also measure, for the first time, the relative intensity noise of an amplifier operating in the gain-managed nonlinear regime. The measurements reveal a significant contribution of the amplification process to the overall output noise of the system.
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| 39. |
- Tomaszewska-Rolla, Dorota, et al.
(författare)
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Mid-IR optical frequency comb Fourier transform spectroscopy using an antiresonant hollow-core fiber
- 2023
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Ingår i: 2023 conference on lasers and electro-optics Europe & European quantum electronics conference (CLEO/Europe-EQEC). - : IEEE. - 9798350345995 - 9798350346008
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Konferensbidrag (refereegranskat)abstract
- Optical frequency combs (OFCs) enable high resolution, sensitivity, and speed in spectroscopic measurements. An efficient way of generating an optical frequency comb in the mid-infrared (mid-IR) is the difference frequency generation (DFG) process, which involves the interaction of two input waves in a non-linear crystal, resulting in the generation of a third wave with a frequency that is the difference in frequency of the two input beams [1]. The classical way of extending the path of light-gas interaction in spectroscopic measurements, thus increasing the sensitivity, is to use multi-pass cells (MPC). However, MPCs have disadvantages related to the difficulty of aligning laser light into the cell or optical fringes. An alternative approach is to use the so-called antiresonant hollow-core fibres (ARHCF) [2]. ARHCFs are characterized by a wide low-loss transmission range in the mid-IR, high quality of the delivered beam, and their air core can be filled with the target gas sample, which makes them well suited for laser-based gas sensing.
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| 40. |
- Vieira, Francisco Senna, et al.
(författare)
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Continuous-filtering Vernier spectrometer with improved design and performance
- 2020
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Ingår i: Optics InfoBase Conference Papers. - : The Optical Society. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- We present a robust cavity-enhanced comb-based spectrometer with a 6.6 GHz resolution and 60 Hz acquisition rate, based on the continuous-filtering Vernier principle, a fixed diffraction grating, a custom-made chopper wheel, and a low-bandwidth comb-cavity stabilization scheme. We measure a CO2 spectrum with 5 x 10-8 cm-1 sensitivity in 17 ms.
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| 41. |
- Vieira, Francisco Senna, et al.
(författare)
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Robust, Fast and Sensitive Near-Infrared Continuous-Filtering Vernier Spectrometer
- 2020
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Ingår i: 2020 Conference on Lasers and Electro-Optics (CLEO). - : IEEE. - 9781943580767 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- We present a new robust approach to cavity-enhanced comb spectroscopy based on Vernier filtering, a fixed diffraction grating, custom-made chopper wheel, and a low bandwidth comb-cavity stabilization scheme. We measure a CO2 spectrum with a few GHz resolution and 5 x 10-8 cm-1 sensitivity in 9.4 ms.
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