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1.
This paper describes a tunable diode laser spectrometer for the in situ measurement of methane by high-resolution absorption
spectroscopy of roto-vibrational lines, using a distributed feedback laser emitting in the near infrared (1.65 μm) and a multi-pass
cell, with a two-tone detection scheme. The instrument was designed to be installed on the high-altitude aircraft M55 Geophysica,
for high-sensitivity and high-temporal-resolution measurement of CH4, both as a greenhouse gas and as a tracer of air-mass motion. The instrument-design criteria to achieve the compactness,
low weight, and ruggedness necessary for automatic operation on an unpressurized high-altitude aircraft are reported. Results
of the laboratory testing are also shown and discussed.
Received: 1 April 2002 / Revised version: 28 May 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +39-050/313-7597, E-mail: damato@scintec.it 相似文献
2.
We describe a 7.4-μm source based on difference frequency generation with 6.5 mW of 1278-nm radiation from an extended cavity
laser and 66 mW of 1544-nm radiation from another extended cavity laser, amplified in an erbium-doped fibre amplifier. Optimum
focusing of the input beams in the 5×5×10-mm3 AgGaSe2 crystal, and the spatial and temporal characteristics of the output beam, are determined. The source is used for accurate
determination of line parameters for selected lines of the ν3 band of SO2, centred at 1361 cm-1. Subsequently, these lines are used for performing quantitative analysis of gas mixtures containing SO2 at concentration levels down to 4 ppm without relying on any calibration with certified gas mixtures. This demonstrates the
potential of infrared spectroscopy as a primary method for low-concentration gas analysis.
Received: 16 January 2003 / Revised version: 19 February 2003 / Published online: 9 April 2003
RID="*"
ID="*"Corresponding author. Fax: +45-4593/1137, E-mail: jh@dfm.dtu.dk 相似文献
3.
S.T. Sanders 《Applied physics. B, Lasers and optics》2002,75(6-7):799-802
A swept-wavelength source is created by connecting four elements in series: a femtosecond fiber laser at 1.56 μm, a non-linear
fiber, a dispersive fiber and a tunable spectral bandpass filter. The 1.56-μm pulses are converted to super-continuum (1.1–2.2 μm)
pulses by the non-linear fiber, and these broadband pulses are stretched and arranged into wavelength scans by the dispersive
fiber. The tunable bandpass filter is used to select a portion of the super-continuum as a scan-wavelength output. A variety
of scan characteristics are possible using this approach. As an example, an output with an effective linewidth of approximately
1 cm-1 is scanned from 1350–1550 nm every 20 ns. Compared to previous scanning benchmarks of approximately 1 nm/μs, such broad,
rapid scans offer new capabilities: a gas sensing application is demonstrated by monitoring absorption bands of H2O, CO2, C2H2 and C2H6O at a pressure of 10 bar.
Received: 5 August 2002 / Revised version: 23 September 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +1-608/265-2316, E-mail: ssanders@engr.wisc.edu 相似文献
4.
G. Totschnig M. Lackner R. Shau M. Ortsiefer J. Rosskopf M.C. Amann F. Winter 《Applied physics. B, Lasers and optics》2003,76(5):603-608
A single-frequency VCSEL has been used for the first time for high-resolution spectroscopy near 1.5 μm. The incorporated buried-tunnel-junction
technology enabled the realization of a long-wavelength InGaAlAs/InP VCSEL with low threshold current (0.925 mA), high output
powers (0.576 mW) and low series resistance (60 Ω). The high-speed tuning capability of the long-wavelength VCSEL was investigated
and used to conduct high-speed absorption spectroscopy. The peak tuning speed was measured to be 3.4 cm-1/μs and a 4.5-cm-1-wide NH3 spectrum was recorded in 2 μs. The VCSEL was used to measure highly resolved low-pressure spectra for pressures ranging from
9.6 mbar to 1 bar. The measured Doppler-broadened linewidth of 0.02 cm-1 agrees within 3% with the theoretical calculations. The availability and various advantages of 1.3–2-μm single-frequency
VCSELs as compared to edge-emitting diode lasers, such as a large current tuning range even at very high tuning frequencies,
and low production costs, should significantly expand the application fields for near-infrared laser gas sensors.
Received: 17 July 2002 / Revised version: 4 December 2002 / Published online: 12 May 2003
RID="*"
ID="*"Corresponding author. Fax: +43-1/58801-15999, E-mail: Gerhard@Totschnig.com 相似文献
5.
M.W. Todd R.A. Provencal T.G. Owano B.A. Paldus A. Kachanov K.L. Vodopyanov M. Hunter S.L. Coy J.I. Steinfeld J.T. Arnold 《Applied physics. B, Lasers and optics》2002,75(2-3):367-376
A novel instrument, based on cavity-ringdown spectroscopy (CRDS), has been developed for trace gas detection. The new instrument
utilizes a widely tunable optical parametric oscillator (OPO), which incorporates a zinc–germanium–phosphide (ZGP) crystal
that is pumped at 2.8 μm by a 25-Hz Er,Cr:YSGG laser. The resultant mid-IR beam profile is nearly Gaussian, with energies
exceeding 200 μJ/pulse between 6 and 8 μm, corresponding to a quantum conversion efficiency of approximately 35%. Vapor-phase
mid-infrared spectra of common explosives (TNT, TATP, RDX, PETN and Tetryl) were acquired using the CRDS technique. Parts-per-billion
concentration levels were readily detected with no sample preconcentration. A collection/flash-heating sequence was implemented
in order to enhance detection limits for ambient air sampling. Detection limits as low as 75 ppt for TNT are expected, with
similar concentration levels for the other explosives.
Received: 1 April 2002 / Revised version: 13 June 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +1-408/524-0551, E-mail: mtodd@picarro.com 相似文献
6.
A versatile CO laser-based photoacoustic spectrometer is presented equipped with three photoacoustic cells placed inside the
laser cavity. The newly designed CO laser can operate both in the Δv=1 and the Δv=2 modes (5.1–8.0 μm and 2.8–4.1 μm) on 400
laser lines. Improved laser operation originating from a better cooling of the gas discharge was evidenced by a shift of the
laser output power to lower J-values. Due to the wide emission range of the source, many molecules of biological and atmospheric
interest, including methane and ethane, can be detected with sensitivities typically at the (sub)ppb level. Measurement of
the respiration of a cockroach showed that the spectrometer is not only sensitive, but also has a good time response (8 s
at a flow rate of 10 l/h).
Received: 3 April 2002 / Revised version: 14 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Current address: Soegijapranata Catholic University, Department of Food Technology, Jalan Pawiyatan Luhur IV/1 Bendan
Duwur, P.O. Box 8033/SM, Semarang 50234, Indonesia
RID="**"
ID="**"Current address: Sanata Dharma University, FMIPA, Kampus III, Paingan, Maguwoharjo, Depok, Sleman, Tromol Pos 29, Yogyakarta
55002, Indonesia
RID="***"
ID="***"Corresponding author. Fax: +31-24/365-3311, E-mail: fransh@ sci.kun.nl 相似文献
7.
C. Dölle C. Reinhardt P. Simon B. Wellegehausen 《Applied physics. B, Lasers and optics》2002,75(6-7):629-634
. Investigations of the efficient generation of powerful coherent radiation at 82.8 nm by frequency tripling of short-pulse
KrF laser radiation are presented. Argon gas is selected as nonlinear medium due to the resonantly enhanced 3rd-order susceptibility
χ(3)(-3ω,ω,ω,ω). Pulse energies of 100 μJ at 82.8 nm have been measured for a pump pulse energy of 14 mJ. An upscaling to more
than 500 μJ is expected with available more powerful pump lasers. Features of this XUV source and possible applications are
discussed.
Received: 26 July 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-511/7622211, E-mail: reinhardt@iqo.uni-hannover.de 相似文献
8.
L.E. Batay A.A. Demidovich A.N. Kuzmin A.N. Titov M. Mond S. Kück 《Applied physics. B, Lasers and optics》2002,75(4-5):457-461
A new laser medium – Yb,Tm:KY(WO4)2 – for diode pumped solid state laser applications operating around 1.9 to 2.0 μm has been investigated and the main laser
characteristics are presented. Diode pumping at 981 nm and around 805 nm was realised. For 981-nm pumping, the excitation
occurs into Yb3+ ions followed by an energy transfer to Tm3+ions. A slope efficiency of 19% was realised. For pumping around 805 nm, the excitation occurs directly into the Tm3+ ions. Here a maximum slope efficiency of 52%, an optical efficiency of 40%, and output powers of more than 1 W were realised.
Using a birefringent quartz plate as an intracavity tuning element, the tunability of the Yb,Tm:KY(WO4)2 laser in the spectral range of 1.85–2.0 μm has been demonstrated. The possibility of laser operation in a microchip cavity
configuration for this material has also been shown.
Received: 12 March 2002 / Revised version: 20 May 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-531/592-4116, E-mail: stefan.kueck@ptb.de 相似文献
9.
By optically pumping the deuterated isotopomers of 14NH3 and 15NH3 using 12C16O2, 13C16O2, 12C18O2, and 13C18O2 lasers, several new far-infrared (FIR) emission lines between 65 μm and 125 μm have been detected. The existing spectroscopy
of 14N-ammonia isotopomers has been used to identify many of these lines, as well as some previously observed but unidentified.
The spectroscopic data have been analyzed to predict over 20 additional FIR laser lines that could be pumped by a more capable
CO2 laser. This effort was motivated by a need for strong laser lines in frequency coincidence with molecular transitions of
astrophysical interest. Of particularnote is the measurement of the 2680-GHz line of 14NHD2, whose frequency is 4.9 GHz higher than that of the important J=1-0 line of interstellar HD.
Received: 25 July 2002 / Published online: 20 December 2002
RID="*"
ID="*"Corresponding author. Fax: +1-303/492-5941, E-mail: boreiko@spot.colorado.edu 相似文献
10.
A.V. Karabutov V.D. Frolov E.N. Loubnin A.V. Simakin G.A. Shafeev 《Applied Physics A: Materials Science & Processing》2003,76(3):413-416
Low-threshold field electron emission (FEE) is reported for periodic arrays of micro-tips produced by laser ablation of Si
wafers. The best samples show emission at threshold fields as low as 4–5 V/μm for n-type Si substrates and of 1–2 V/μm for
p-doped Si substrates, as measured with a flat-screen technique. Auger electron spectroscopy and X-ray electron spectroscopy
reveal island-like deviation of the SiO2 stoichiometry on the tip surfaces, with lateral dimensions of less than 100 nm. Microscopic studies using a special field-emission
STM show that the emission originates from well-conducting regions of sub-micron size. The experimental data suggest FEE from
the tip arrays by a geometric field enhancement of both the individual micro-tip and the narrow conducting channels in the
tip body.
Received: 3 May 2002 / Accepted: 1 July 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +7-095/135-82-34, E-mail: shafeev@kapella.gpi.ru 相似文献
11.
A compact, diode-based difference-frequency laser system combined with a photoacoustic detection scheme is presented for trace-gas
sensing. It features a broad, continuous tuning range (3.2–3.7 μm), a narrow line width (154 MHz), and room-temperature operation,
and thus allows numerous gas species to be measured both isolated and in mixtures of different gases. Several trace-gas species
of environmental interest were detected, and gas mixtures were analysed. The detection limits are in the low-ppmV range, e.g.
1.3 ppmV for methane, 1.8 ppmV for ethane, and 1.2 ppmV for hydrogen chloride.
Received: 10 April 2002 / Revised version: 5 June 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1077, E-mail: Sigrist@iqe.phys.ethz.ch 相似文献
12.
Kosterev AA Curl RF Tittel FK Rochat M Beck M Hofstetter D Faist J 《Applied physics. B, Lasers and optics》2002,75(2-3):351-357
Pulsed thermoelectrically cooled QC-DFB lasers operating at 15.6 μm were characterized for spectroscopic gas sensing applications.
A new method for wavelength scanning based on repetition rate modulation was developed. A non-wavelength-selective pyroelectric
detector was incorporated in the sensor configuration giving the advantage of room-temperature operation and low cost. Absorption
lines of CO2 and H2O were observed in ambient air, providing information about the concentration of these species.
Received: 29 April 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-713/348-5686, E-mail: akoster@rice.edu 相似文献
13.
We present the first photoacoustic spectrometer for gas sensing employing both the fundamental and the frequency-doubled radiation
of a continuously tunable high-pressure CO2 laser with room temperature operation. A quasi-phase-matched diffusion-bonded GaAs crystal is used in the system for second-harmonic
generation. A pulsed photoacoustic detection scheme with a non-resonant cell, equipped with an 80-microphone array, is employed.
The wide continuous tuning range in the fundamental (9.2–10.7 μm) and the frequency-doubled (4.6–5.35 μm) regimes, together
with the narrow linewidth of 540 MHz (0.018 cm-1) for the 10-μm region and of 1050 MHz (0.0315 cm-1) for the 5-μm region, allow the measurement of gas mixtures, individual species and isotope discrimination. This is illustrated
with measurements on NO and CO2. The measured isotope ratio 15
NO/14
NO=(3.58±0.55)×10-3 agrees well with the literature (3.700×10-3) and demonstrates the good selectivity of the system.
Received: 30 April 2002 / Revised version: 10 June 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1077, E-mail: sigrist@iqe.phys.ethz.ch 相似文献
14.
A 50 cm silver coated hollow fiber with inner diameter of 250 μm and filled with argon has been used to compress optical pulses
from a Ti:sapphire laser at 800 nm. Input pulses with energy of 250 μJ and duration of 110 fs were used and compressed pulses
with energy of 220 μJ and duration of 20 fs were generated by using a prism compressor. Numerical and experimental results
are compared. There is good agreement between the measured beam diameters of the hollow-fiber output pulse and the calculated
values obtained from propagation of the HE11 mode into free space. For comparison, a similar uncoated fused-silica hollow fiber was also used to obtain 20 fs compressed
pulses with an energy of 190 μJ.
Received: 7 September 2002 / Published online: 26 March 2003
RID="*"
ID="*"Corresponding author. Fax: +1-780/492-1811, E-mail: mohebbi@ee.ualberta.ca 相似文献
15.
V.G. Savitski N.N. Posnov P.V. Prokoshin A.M. Malyarevich K.V. Yumashev M.I. Demchuk A.A. Lipovskii 《Applied physics. B, Lasers and optics》2002,75(8):841-846
Passive mode locking and saturable absorber Q-switching of neodymium lasers at 1.3 μm with PbS-doped phosphate glasses are
demonstrated. Q-switched pulses of 120 ns (0.1 μJ) in duration (energy) and the average output power of 3 mW from a quasi-cw
diode-pumped Nd3+:KGW laser and ultrashort pulses of a maximum of 250 μJ in energy and 150 ps in duration from a Nd3+:YAP laser were obtained. The bleaching decay rate of the samples was found to increase with the Quantum Dot’s size decreasing
due to the enhancement of quantum confinement effects for smaller dots and stronger overlapping of the electron and trap state
wave functions.
Received: 23 January 2002 / Revised version: 2 April 2002 / Published online: 20 December 2002
RID="*"
ID="*"Corresponding author. Fax: +375-17/232-6286, E-mail: savitski@eudoramail.com 相似文献
16.
The generation of programmable complex femtosecond pulses in the mid infrared (3–10 μm) with high precision is reported. Designed
pulse shapes in the near infrared (1–1.6 μm) are transferred to the mid infrared via difference-frequency mixing with a second
infrared pulse spectrally narrowed in a zero-dispersion compressor. In particular, pulse sequences with variable relative
phases have been obtained. The control of the pulse properties is achieved purely electronically, allowing for implementation
into a feedback loop.
Received: 12 December 2003 / Published online: 3 April 2003
RID="*"
ID="*"Corresponding author. Fax: +49-89/32905-200, E-mail: mcm@mpq.mpg.de 相似文献
17.
A portable modular gas sensor for measuring the 13C/12C isotopic ratio in CO2 with a precision of 0.8‰(±1σ) was developed for volcanic gas emission studies. This sensor employed a difference frequency generation (DFG)-based spectroscopic
source operating at 4.35 μm (∼2300 cm-1) in combination with a dual-chamber gas absorption cell. Direct absorption spectroscopy using this specially designed cell
permitted rapid comparisons of isotopic ratios of a gas sample and a reference standard for appropriately selected CO2 absorption lines. Special attention was given to minimizing undesirable precision degrading effects, in particular temperature
and pressure fluctuations.
Received: 16 April 2002 / Revised version: 28 May 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-713/5245237, E-mail: fkt@rice.edu 相似文献
18.
Development of a tunable mid-IR difference frequency laser source for highly sensitive airborne trace gas detection 总被引:4,自引:0,他引:4
Richter D Fried A Wert BP Walega JG Tittel FK 《Applied physics. B, Lasers and optics》2002,75(2-3):281-288
The development of a compact tunable mid-IR laser system at 3.5 μm for quantitative airborne spectroscopic trace gas absorption
measurements is reported. The mid-IR laser system is based on difference frequency generation (DFG) in periodically poled
LiNbO3 and utilizes optical fiber amplified near-IR diode and fiber lasers as pump sources operating at 1083 nm and 1562 nm, respectively.
This paper describes the optical sensor architecture, performance characteristics of individual pump lasers and DFG, as well
as its application to wavelength modulation spectroscopy employing an astigmatic Herriott multi-pass gas absorption cell.
This compact system permits detection of formaldehyde with a minimal detectable concentration (1σ replicate precision) of
74 parts-per-trillion by volume (pptv) for 1 min of averaging time and was achieved using calibrated gas standards, zero air
background and rapid dual-beam subtraction. This corresponds to a pathlength-normalized replicate fractional absorption sensitivity
of 2.5×10-10 cm-1.
Received: 29 April 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-303/497-1492, E-mail: dr@ucar.edu 相似文献
19.
We developed a high-power oscillator–regenerative amplifier femtosecond laser system. Based on chromium-doped forsterite.
The system is operating near 1.25 μm at a 5–10 kHz repetition rate. Chirped-pulse amplification produced 0.86 W (0.75 W) of
average power, or 465 mW (400 mW) after compression at 5 kHz (10 kHz). Nearly bandwidth-limited pulses of duration 135 fs
(shortest) and 150 fs (typical) are available with an energy of 93 μJ and 40 μJ at 5 and 10 kHz, respectively.
Received: 7 June 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-30/63921289, E-mail: petrov@mbi-berlin.de 相似文献
20.
V. Brien A. Dauscher P. Weisbecker F. Machizaud 《Applied Physics A: Materials Science & Processing》2003,76(2):187-195
The preparation in thin film form of the known icosahedral phase in Ti-Ni-Zr bulk alloys has been investigated as a function
of substrate temperature. Films were deposited by pulsed laser deposition on sapphire substrates at temperatures ranging from
room temperature to 350 °C. Morphological and structural modifications have been followed by grazing-incidence and θ–2θ X-ray
diffraction, transmission electron diffraction and imaging. Chemical composition has been analyzed by electron probe microanalysis.
The in-depth variation of composition has been studied by secondary neutral mass spectroscopy. We show that pulsed laser deposition
at 275 °C makes the formation of a 1-μm-thick film of Ti-Ni-Zr quasicrystalline textured nanocrystallites possible.
Received: 7 June 2001 / Accepted: 18 February 2002 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +33-3/8357-6300, E-mail: brien@mines.u-nancy.fr 相似文献