共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Berrou M. Raybaut A. Godard M. Lefebvre 《Applied physics. B, Lasers and optics》2010,98(1):217-230
An entangled cavity doubly resonant optical parametric oscillator (ECOPO) has been developed to provide tunable narrow line
width (<100 MHz) pulsed (8 ns) radiation over the 3.8–4.3 μm spectral range at a multi-kilohertz repetition rate with up to
100-W peak power. We demonstrate that coarse single mode tuning is obtained over the full spectral range of oscillation (300
cm−1), while automated mode-hop-free fine tuning is carried out over more than 100 GHz. High-resolution spectra of main greenhouse
gases (CO2, N2O, SO2 and CH4) have been obtained in good agreement with calculated spectra from the HITRAN database. These experiments outline the unique
capabilities of the ECOPO for multi-gas sensing based on direct absorption as well as photoacoustic spectroscopy. 相似文献
2.
A.K.Y. Ngai S.T. Persijn I.D. Lindsay A.A. Kosterev P. Gro? C.J. Lee S.M. Cristescu F.K. Tittel K.-J. Boller F.J.M. Harren 《Applied physics. B, Lasers and optics》2007,89(1):123-128
A continuous wave optical parametric oscillator, generating up to 300 mW idler output in the 3–4 μm wavelength region, and
pumped by a fiber-amplified DBR diode laser is used for trace gas detection by means of quartz-enhanced photoacoustic spectroscopy
(QEPAS). Mode-hop-free tuning of the OPO output over 5.2 cm-1 and continuous spectral coverage exceeding 16.5 cm-1 were achieved via electronic pump source tuning alone. Online monitoring of the idler wavelength, with feedback to the DBR
diode laser, provided an automated closed-loop control allowing arbitrary idler wavelength selection within the pump tuning
range and locking of the idler wavelength with a stability of 1.7×10-3 cm-1 over at least 30 min.
Using this approach, we locked the idler wavelength at an ethane absorption peak and obtained QEPAS data to verify the linear
response of the QEPAS signal at different ethane concentrations (100 ppbv-20 ppmv) and different power levels. The detection
limit for ethane was determined to be 13 ppbv (20 s averaging), corresponding to a normalized noise equivalent absorption
coefficient of 4.4×10-7 cm-1 W/Hz1/2.
PACS 42.55.Wd; 42.65.Yj; 42.62.Fi 相似文献
3.
M. Andachi T. Nakayama M. Kawasaki S. Kurokawa H.-P. Loock 《Applied physics. B, Lasers and optics》2007,88(1):131-135
Visible and near-infrared laser light pulses were coupled into two different types of optical fiber cavities. One cavity consisted
of a short strand of fiber waveguide that contained two identical fiber Bragg gratings. Another cavity was made using a loop
of optical fiber. In either cavity ∼40 ps laser pulses, which were generated using a custom-built gain-switched diode laser,
circulated for a large number of round trips. The optical loss of either cavity was determined from the ring-down times. Cavity
ring-down spectroscopy was performed on 200 pL volumes of liquid samples that were injected into the cavities using a 100 μm
gap in the fiber loop. A detection limit of 20 ppm of methylene blue dye in aqueous solution, corresponding to a minimum absorptivity
of εC<6 cm-1, was realized.
PACS 42.62.Fi; 42.81.-i 相似文献
4.
J. Peltola M. Vainio V. Ulvila M. Siltanen M. Metsälä L. Halonen 《Applied physics. B, Lasers and optics》2012,107(3):839-847
We demonstrate an off-axis cavity ring-down spectroscopy system, which uses a mid-infrared continuous-wave optical parametric oscillator as a light source. Off-axis injection with re-entrant configuration of the ring-down cavity is used to achieve high spectral resolution while maintaining high measurement speed. This makes the setup suitable for sensitive molecular spectroscopy in the mid-infrared region, particularly for studies that require high temporal resolution. Formaldehyde (H2CO) absorption spectrum at 3.4 µm is measured using the off-axis re-entrant cavity ring-down spectrometer. 相似文献
5.
A pulsed optical parametric oscillator (OPO) operated in an optical cavity with a grazing-incidence grating configuration
(GIOPO) was used for sensitive photoacoustic detection of trace quantities of dinitrogen oxide (N2O). The (ν1+ν3) combination vibration band of N2O was excited with the idler beam of the GIOPO at 2.86 μm using an optical cavity optimized for the idler beam. The linewidth
of the GIOPO could be reduced to 0.4 cm-1, allowing the rotational structure of the absorption spectrum to be resolved. A concentration sensitivity (signal-to-noise
ratio=3) of 60 parts in 109 by volume (60 ppb V) N2O in synthetic air was obtained. This may be sufficient for continuous monitoring of N2O in the atmosphere.
Received: 29 April 2002 / Revised version: 4 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +49-6221/54-4255, E-mail: peter.hess@urz.uni-heidelberg.de 相似文献
6.
We present a portable spectrometer that uses the frequency-stabilized cavity ring-down spectroscopy technique capable of high-precision measurements of trace water vapor concentration. Measuring one of the strongest rovibrational transitions in the ν1+ν3 water vapor combination band near ˜ν=7181.156 cm-1, we compare spectroscopic and thermodynamic determinations of trace water vapor in N2, and find systematic differences attributable to water vapor background effects and/or uncertainties in line intensities. We also compare the frequency-stabilized ring-down method with other cavity ring-down approaches that are based on unstabilized probe lasers and unstabilized ring-down cavities. We show that for the determination of water vapor concentration, the frequency-stabilized cavity ring-down method has the minimum measurement uncertainty of these techniques. The minimum noise-equivalent absorption coefficient of the spectrometer was 1.2×10-10 cm-1 Hz-1/2, which further corresponds to a minimum detectable water vapor mole fraction equal to 0.7×10-9 for an absorption spectrum of 10 minutes duration. PACS 33.20.-t; 33.70.Jg; 33.70.Fd; 42.62.Fi 相似文献
7.
A. Rihan E. Andrieux T. Zanon-Willette S. Briaudeau M. Himbert J.-J. Zondy 《Applied physics. B, Lasers and optics》2011,102(2):367-374
We report on a widely tunable continuous-wave single-frequency pump-resonant signal-resonant optical parametric oscillator
(PRSRO) delivering 20 mW to 50 mW of idler power spanning an octave bandwidth in the mid-infrared (1.7 μm and 3.5 μm). The
PRSRO is pumped by a Ti:Al2O3 ring laser delivering 760 mW around λ
p
=795 nm, and thanks to the pump enhancement a threshold as low as 110 mW is achieved with a multi-grating temperature-tuned
MgO-doped periodically-poled LiNbO3. This PRSRO will be used for multi-species trace gas sensing based on cavity ring-down spectroscopy. 相似文献
8.
F. Kühnemann K. Schneider A. Hecker A.A.E. Martis W. Urban S. Schiller J. Mlynek 《Applied physics. B, Lasers and optics》1998,66(6):741-745
2 H6) at 3.34 μm using a widely tunable cw single-frequency optical parametric oscillator. The high frequency and power stability
and the continuous tunability of the parametric oscillator make it ideally suited for this application. Detection sensitivities
of 0.5 ppb for ethane are obtained, which is comparable to the best results previously obtained with intracavity detection
using line-tunable CO overtone lasers. The flexibility and compact size of cw single-frequency parametric oscillators can
lead to portable photoacoustic trace-gas detection systems for environmental monitoring and process control.
Received: 28 January 1998/Revised version: 9 April 1998 相似文献
9.
Ultra-sensitive mid-infrared cavity leak-out spectroscopy using a cw optical parametric oscillator 总被引:1,自引:0,他引:1
A. Popp F. Müller F. Kühnemann S. Schiller G. von Basum H. Dahnke P. Hering M. Mürtz 《Applied physics. B, Lasers and optics》2002,75(6-7):751-754
We report a portable, all-solid-state, mid-infrared spectrometer for trace-gas analysis. The light source is a continuous-wave
optical parametric oscillator based on PPLN and pumped by a Nd:YAG laser at 1064 nm. The generated single-frequency idler
output covers the wavelength region between 2.35 and 3.75 μm. With its narrow line width, this light source is suitable for
precise trace-gas analysis with very high sensitivity. Using cavity leak-out spectroscopy we achieved a minimum detectable
absorption coefficient of 1.2×10-9 /cm (integration time: 16 s), corresponding, for example, to a detection limit of 300 parts per trillion ethane. This sensitivity
and the compact design make this trace-gas analyzer a promising tool for various in situ environmental and medical applications.
Received: 19 September 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-228/733-474, E-mail: frank.kuehnemann@iap.uni-bonn.de 相似文献
10.
J. Luque J.B. Jeffries G.P. Smith D.R. Crosley 《Applied physics. B, Lasers and optics》2001,73(7):731-738
The combination of two-dimensional, planar laser-induced fluorescence (PLIF) and cavity ring-down (CRD) absorption spectroscopy
is applied to map quantitatively the spatial distributions of CH2O and CH in a methane/air flame at 25 Torr. Both species are detected in the same spectral region using the overlapping CH2O A 1
A
2
-X
1
A
1
41
0 and CH B-X(1,0 )bands. The combination of diagnostic techniques exploits the spatial resolution of LIF and the quantitative
CRD absorption measure of column density. The spatially resolved PLIF provides the distribution of absorbers and line-of-sight
CRD absorption the absolute number density needed for quantitative concentration images. The peak CH2O concentration is (3.5±1.4 )×1014 cm-3, or 1450±550 ppm at 1000 K. The lack of precise absorption cross-section data produces these large error limits. Although
a flame model predicts lower amounts, these large uncertainties limit this measurement’susefulness as a test of the flame
chemistry.
Received: 24 April 2001 / Revised version: 10 July 2001 / Published online: 10 October 2001 相似文献
11.
Selective and sensitive detection of formaldehyde (CH2O) was achieved using a grazing-incidence optical parametric oscillator (GIOPO), pumped at high repetition rate, as a light source for photoacoustic spectroscopy. The photoacoustic spectrum of formaldehyde was measured in the range from 2785 to 2840 cm-1 and an absorption line at 2805.0 cm-1 was selected for detection. Concentrations down to 20 ppbv (parts per billion by volume) formaldehyde in nitrogen were recorded. The detection limit determined by background fluctuations was 3 ppbv (S/N=1) for 3 s lock-in time constant and 3 min acquisition time. The 2805.0 cm-1 absorption line of the ν1 vibrational mode was chosen because of the absence of interference with water and carbon-dioxide bands. This allowed the direct detection of formaldehyde in laboratory air without filtering. PACS 42.62.Fi; 42.68.Ca; 42.65.Yj; 07.07.Df 相似文献
12.
O.Yu. Nikiforova V.A. Kapitanov Yu.N. Ponomarev 《Applied physics. B, Lasers and optics》2008,90(2):263-268
Spectra measurements around 1.65 μm have revealed that spectral lines of ethylene are present in this range along with methane
spectral lines. Furthermore, the HITRAN database has no parameters of these ethylene lines. In particular, it was found that
several ethylene absorption lines are located near the methane feature often used for quantitative spectroscopy (R3 triplet
of the 2ν3 band). Ethylene can be present together with methane in the samples under study, perturbing the recorded spectrum of CH4. This perturbation by an interfering species can produce systematic errors in the derived CH4 concentration.
We have found in this work by numerical modelling that when measuring the methane concentration by a diode laser methane sensor
operating in the 6046–6048 cm-1 range, the systematic error on the retrieved CH4 concentration decreases, as a rule, when decreasing the width of the fitted spectral window. At equal concentrations of ethylene
and methane in the sample under study, the error on the concentration of CH4 determined by the correlation technique can reach 15%. When using the technique based on the 2nd or 3rd derivative of the
spectrum, interfering or impurity lines induce a systematic error on the derived CH4 concentration, which is less than 2%.
PACS 07.07.Df; 07.88.+y; 42.62.-b 相似文献
13.
We report a continuous-wave singly resonant optical parametric oscillator (SRO) with more than 12 W of idler power at 3414
nm when it was operated at 30°C. The SRO was directly pumped by a single-frequency, ytterbium-doped fiber laser with 49 W
linear polarization pump powers, and based on 50 mm long periodically poled MgO:LiNbO3 crystal (PPMgLN) in two-mirror linear cavity with 30.5 μm grating period. It’s pump power at threshold was 5.4 W. The slope-efficiency
and quantum-limited performance reached 26 and 79.2%, respectively. The beam polarization matched the e → e + e interaction in crystal. The idler waves were temperature tuned in the range of 3654 to 3811 nm and 3248 to 3414 nm based
on two 50 mm long PPMgLN with 29.5 and 30.5 μm grating period. To the best of our knowledge, this is the highest continuouswave
mid-IR output obtained for a fiber laser pumped optical parametric oscillator (OPO). 相似文献
14.
W. Zhao X. Gao W. Chen W. Zhang T. Huang T. Wu H. Cha 《Applied physics. B, Lasers and optics》2007,86(2):353-359
A novel instrument based on an improved off-axis alignment of integrated cavity output spectroscopy (OA-ICOS) in conjunction
with a wavelength modulation (WM) technique, was developed using a DFB diode laser operating in the near infrared at 1.573 μm
(6357.3 cm-1). The laser-based sensor employed a 44 cm optical cavity that provided an effective absorption path length of ∼68 m. A minimum
detectable absorption of approximately 3.6 ppmv Hz-1/2 or 2.3×10-7 Hz-1/2 per optical pass was obtained using second harmonic detection. We demonstrated that by implementation of the WM technique
to OA-ICOS in the near infrared, the detection sensitivity was improved by a factor of 14 compared to that obtained with OA-ICOS.
Measurements of CO2 mixing ratios in ambient air have been performed by using both OA-ICOS and WM-OA-ICOS techniques for performance comparison.
PACS 42.62.Fi; 07.07.Df; 33.20.Ea 相似文献
15.
D. A. Long M. Okumura C. E. Miller J. T. Hodges 《Applied physics. B, Lasers and optics》2011,105(2):471-477
Carbon dioxide (CO2) isotopic ratios on samples of pure CO2 were measured in the 1.6 μm wavelength region using the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) technique.
We present CO2 absorption spectra with peak signal-to-noise ratios as high as 28,000:1. Measured single-spectrum signal-to-noise ratios
were as high as 8900:1, 10,000:1, and 1700:1 for 13C/12C, 18O/16O, and 17O/16O, respectively. In addition, we demonstrate the importance of utilizing the Galatry line profile in the spectrum analysis.
The use of the Voigt line profile, which neglects the observed collisional narrowing, leads to large systematic errors which
are transition-dependent and vary with temperature and pressure. While the relatively low intensities of CO2 transitions near λ=1.6 μm make this spectral region non-optimal, the sensitivity and stability of FS-CRDS enabled measurement precision of pure
CO2 samples which are comparable to those of other optical techniques which operate at far more propitious wavelengths. These
results indicate that a FS-CRDS spectrometer designed to probe CO2 bands near wavelengths of 2.0 μm or 4.3 μm could achieve significantly improved precision over the present instrument and
likely be competitive with mass spectrometric methods. 相似文献
16.
M.M.J.W. van Herpen A.K.Y. Ngai S.E. Bisson J.H.P. Hackstein E.J. Woltering F.J.M. Harren 《Applied physics. B, Lasers and optics》2006,82(4):665-669
A continuous wave, single frequency and continuously tunable optical parametric oscillator is used in combination with photoacoustic spectroscopy to detect trace emissions of CO2 from insects under atmospheric conditions. The optical parametric oscillator (OPO) contains a periodically poled lithium niobate crystal and is tunable over the 3.9 to 4.8 μm infrared wavelength region. With the strong rotational-vibrational absorption band of CO2 at 4.23 μm, it is possible to detect CO2 down to 7 parts per billion volume using 20 mW of the OPO beam. This detection sensitivity was achieved by adding 4% of SF6 gas to the atmospheric gas mixture to overcome the slow vibrational relaxation of the excited CO2 levels. The usefulness of this system is demonstrated by real-time measuring of the fluctuations of the CO2 concentration in the breath of a single ant (Lasius niger) and individual fruit flies (Drosophila melanogaster). PACS 42.65.Yj; 82.80.Kq; 42.62.Fi 相似文献
17.
D. D. Arslanov M. Spunei A. K. Y. Ngai S. M. Cristescu I. D. Lindsay S. T. Persijn K. J. Boller F. J. M. Harren 《Applied physics. B, Lasers and optics》2011,103(1):223-228
A fiber-amplified Distributed Bragg Reflector diode laser is used to pump a continuous wave, singly resonant Optical Parametric
Oscillator (OPO). The output radiation covers the 3–4 μm with ability of rapid (100 THz/s) and broad mode-hop-free tuning
(5 cm−1). Wavelength Modulation Spectroscopy is combined with the OPO to take optimal advantage of the spectral scan speed. The sensitivity
of the system was determined as 0.8 ppbv (parts-per-billion by volume) for ethane (C2H6) for the absorption peak at 2996.9 cm−1 recorded in 1.3 seconds, corresponding to a noise equivalent absorption sensitivity (NEAS) of 1.2×10−9 cm−1/Hz1/2. A comparison between results using the 1st, 2nd and 4th harmonic derivative signal from wavelength modulation was performed. The broad continuous tunability was demonstrated by
covering 35 cm−1 while recording absorption features of ethane, methane and water. 相似文献
18.
Isotopic ratio measurement of methane in ambient air using mid-infrared cavity leak-out spectroscopy 总被引:1,自引:0,他引:1
H. Dahnke D. Kleine W. Urban P. Hering M. Mürtz 《Applied physics. B, Lasers and optics》2001,72(1):121-125
We report on infrared laser spectroscopic measurements of the isotopic composition of methane (12CH4, 13CH4) in natural air samples with a cavity ring-down technique. A CO overtone sideband laser is utilized to excite a high-finesse
cavity which provides an effective optical absorption path length of 3.6 km. We achieved a detection limit of 105 ppt methane
in ambient air using an integration time of 20 s. This corresponds to a minimum detectable absorption of 1.9×10-9 /cm. Rapid determination of the 13C/12Cisotopic ratio of methane in ambient air without sample preconcentration or gas processing is realized. The present system
requires only few minutes for an isotopic ratio measurement with a precision of 11%o .
Received: 14 July 2000 / Revised version: 25 October 2000 / Published online: 6 December 2000 相似文献
19.
A. I. Yenzhyieuski M. V. Bogdanovich G. I. Ryabtsev V. V. Suprun A. V. Grigor’ev A. G. Ryabtsev M. A. Shchemelev 《Journal of Applied Spectroscopy》2009,76(4):476-481
Judd–Ofelt parameters (Ω2 = 5.09∙10–20, Ω4 = 0.92∙10–20, and Ω6 = 0.63∙10–20 cm2) and oscillator strengths of fundamental optical transitions involved in lasing at wavelength 1.54 μm have been calculated
for borosilicophosphate glass co-activated with Er3+ and Tb3+ ions based on experimental luminescence and absorption spectra and refractive indices. The results were used to determine
the emission (6∙10–23 cm2) and absorption (5∙10–21 cm2) cross sections for λ = 1.54 μm and the gain cross section as a function of inverse population levels. 相似文献
20.
An optical clock based on an Er3+ fiber femtosecond laser and a two-mode He–Ne/CH4 optical frequency standard (λ=3.39 μm) is realized. Difference-frequency generation is used to down convert the 1.5-μm frequency comb of the Er3+ femtosecond laser to the 3.4-μm range. The generated infrared comb overlaps with the He–Ne/CH4 laser wavelength and does not depend on the carrier–envelope offset frequency of the 1.5-μm comb. In this way a direct phase-coherent
connection between the optical frequency of the He–Ne/CH4 standard and the radio frequency pulse repetition rate of the fiber laser is established. The stability of the optical clock
is measured against a commercial hydrogen maser. The measured relative instability is 1×10−12 at 1 s and for averaging times less than 50 s it is determined by the microwave standard, while for longer times a drift
of the He–Ne/CH4 optical standard is dominant. 相似文献