| 1. |
- Foltynowicz, Aleksandra, 1981-, et al.
(author)
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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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In: 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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Journal article (peer-reviewed)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.
(author)
-
Sub-Doppler Double-Resonance Spectroscopy of Methane Using a Frequency Comb Probe
- 2021
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 126:6
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Journal article (peer-reviewed)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.
(author)
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Sub-doppler double-resonance spectroscopy of methane using a frequency comb probe
- 2020
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In: Conference on Lasers and Electro-Optics. - : Optica Publishing Group (formerly OSA). - 9781943580767 - 9781728144184
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Conference paper (peer-reviewed)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. |
- Krzempek, Karol, et al.
(author)
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Compact 6.5 – 9 μm frequency comb source for fourier transform spectroscopy
- 2020
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In: Optics and Photonics for Sensing the Environment. - : The Optical Society. - 9781557528209
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Conference paper (peer-reviewed)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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| 5. |
- Krzempek, Karol, et al.
(author)
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Mid-infrared frequency comb covering the 6.5 – 9 µm range with active output power stabilization
- 2020
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In: Proceedings <em>OSA High-brightness Sources and Light-driven Interactions Congress 2020 (EUVXRAY, HILAS, MICS)</em>. - : The Optical Society. - 9781557528209
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Conference paper (peer-reviewed)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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| 6. |
- Krzempek, Karol, et al.
(author)
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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
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In: Optics Express. - : Optical Society of America. - 1094-4087. ; 27:26, s. 37435-37445
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Journal article (peer-reviewed)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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| 7. |
- Soboń, Grzegorz, et al.
(author)
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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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In: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). - : IEEE. - 9781509067367
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Conference paper (peer-reviewed)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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| 8. |
- Sobon, Grzegorz, et al.
(author)
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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
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In: Optics Letters. - : OPTICAL SOC AMER. - 0146-9592 .- 1539-4794. ; 42:9, s. 1748-1751
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Journal article (peer-reviewed)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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| 9. |
- Szewczyk, Olga, et al.
(author)
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Dual-wavelength pumped highly birefringent microstructured silica fiber for widely tunable soliton self-frequency shift
- 2021
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In: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 39:10, s. 3260-3268
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Journal article (peer-reviewed)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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