共查询到20条相似文献,搜索用时 15 毫秒
1.
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
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ID="*"Corresponding author. Fax: +1-713/5245237, E-mail: fkt@rice.edu 相似文献
2.
J.C. Bermudez Gutierrez M.J. Damzen V.J. Pinto-Robledo A.V. Kir’yanov J.J. Soto-Bernal 《Applied physics. B, Lasers and optics》2003,76(1):13-16
The analysis of compact CW diode-side-pumped grazing-incidence-geometry Nd:YVO4 laser designs is presented. An output power of 5 W (λ=1064 nm) was produced at 17 W of diode pump (conversion efficiency
of 30%) in single transverse TEM00 mode operation at high laser beam quality (Mx
2≈1.05 and My
2≈1.01). The resonator geometry was analyzed by applying generalized 4×4 matrix modeling of the spatial mode size, including
the impact on the laser operation of cavity astigmatism and a thermal lens in the laser slab. The simplicity and compactness
of the laser cavities allow their use for technological applications.
Received: 31 July 2002 / Published online: 22 January 2003
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ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: m.damzen@ic.ac.uk 相似文献
3.
Portable difference-frequency laser-based cavity leak-out spectrometer for trace-gas analysis 总被引:1,自引:0,他引:1
We report a portable mid-infrared spectrometer for trace-gas analysis which is based on an all-solid-state difference-frequency-generation
laser. The spectrometer provides in situ absorption path lengths of more than 3 km by means of the cavity leak-out method,
a cw variant of the cavity ring-down technique. The design, performance, and application of this spectrometer are presented.
The light source utilizes difference-frequency generation in a periodically poled lithium niobate (PPLN) crystal pumped by
two single-frequency solid-state lasers. A maximum power of 27 μW in the wavelength region near 3.3 μm is achieved using a
pump power of 20 mW at 808 nm, a signal power of 660 mW at 1064 nm, and a 50-mm-long PPLN crystal. This corresponds to a conversion
efficiency of 0.42 mW/(W2 cm). We demonstrate that this portable laser system is suitable as a light source in a cavity leak-out spectrometer. We achieved
a minimum detectable absorption coefficient of 1×10-8/cm (integration time: 2 s), corresponding, for example, to a detection limit of 1 part per billion ethane. This compact trace-gas
analyzer with high sensitivity and specificity is promising for various environmental and medical applications.
Received: 8 April 2002 / Revised version: 28 May 2002 / Published online: 21 August 2002
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ID="*"Corresponding author. Fax: +49-211/811-3121, E-mail: muertz@uni-duesseldorf.de 相似文献
4.
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
5.
Spectroscopic sensing of gases can be performed with high sensitivity and photometric precision by cavity ringdown (CRD) absorption
spectroscopy. Our cavity ringdown spectrometer incorporates continuous-wave (cw) tunable diode lasers, fibre-optic coupling
and standard photonics and optical telecommunications components. It comprises a rapidly swept optical cavity in a single-ended
optical heterodyne transmitter–receiver configuration, enabling optical absorption of gases to be recorded either as single-frequency
scanned spectra or as simultaneous, multi-wavelength tailored spectra. By measuring weak near-infrared rovibrational spectra
of carbon dioxide gas (CO2), with high resolution in the vicinity of 1.53 μm, we have realised a noise-limited absorption sensitivity of 2.5×10-9 cm-1 Hz-1/2. Analytical sensitivity limits (both actual and projected) and prospective gas-diagnostic applications are discussed. Our
approach to cw-CRD spectroscopy offers high performance in a relatively simple, low-cost, compact instrument that is amenable
to chemical analysis of trace gases in medical, agricultural, industrial and environmental situations.
Received: 16 May 2002 / Revised version: 3 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +61-2/9850-8313, E-mail: brian.orr@mq.edu.au 相似文献
6.
Sensitive absorption measurements in the near-infrared region using off-axis integrated-cavity-output spectroscopy 总被引:3,自引:0,他引:3
A novel instrument that employs a high-finesse optical cavity as an absorption cell has been developed for sensitive measurements
of gas mixing ratios using near-infrared diode lasers and absorption-spectroscopy techniques. The instrument employs an off-axis
trajectory of the laser beam through the cell to yield an effective optical path length of several kilometers without significant
unwanted effects due to cavity resonances. As a result, a minimum detectable absorption of approximately 1.4×10-5 over an effective optical path of 4.2 km was obtained in a 1.1-Hz detection bandwidth to yield a detection sensitivity of
approximately 3.1×10-11 cm-1 Hz-1/2. The instrument has been used for sensitive measurements of CO, CH4, C2H2 and NH3.
Received: 6 May 2002 / Revised version: 31 May 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +1-650/965-7074, E-mail: d.baer@lgrinc.com 相似文献
7.
An ultra-short-pumped optical dye amplifier operating in the near-IR (720 nm) has been developed. We present an experimental
study of the input–output characteristics of this simple device in a traveling wave collinear configuration. In essence, the
combined effects of the ultrafast nature of the anisotropy induced by the exciting laser pulse along with the short transit
time across the length of the cell allow for optimal output conditions given the number of molecules in the active volume.
Two distinct amplifying regimes have been observed depending on photon density. Typical gain values of 104 of the narrow bandwidth (∼9 nm) subpicosecond output signal were measured. The 8-mm2 beam cross section enables this photon amplifier to be utilized in time-gated imaging applications.
Received: 12 December 2001 / Revised version: 13 May 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +1-819/564-5442, E-mail: Daniel.Houde@Usherbrooke.ca 相似文献
8.
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
9.
E. Schlosser J. Wolfrum L. Hildebrandt H. Seifert B. Oser V. Ebert 《Applied physics. B, Lasers and optics》2002,75(2-3):237-247
The residence-time of the flue gas in a furnace is an important parameter for a complete and clean combustion. A new method
to determine the residence-time has been developed and is presented for the first time. It is based on the injection of alkali
compounds as a tracer. Alkali atoms that are produced by thermal decomposition of the tracer are detected in the hot flue
gas after passage of the combustion facility. This is done without any gas sampling using direct tunable diode laser based
absorption spectroscopy. Different diode laser (DL) types (Fabry–Pérot DLs, external-cavity DLs, and vertical-cavity surface-emitting
lasers) were analyzed and used to develop several spectrometers for the in situ detection of lithium (671 nm), potassium (770 nm), and rubidium (780 nm). Various spectrometers were built for single- or
multi-species detection using a single laser, for time-multiplexed multi-species detection using two lasers, and for multi-path
detection at two different locations along the flue-gas duct. To evaluate the system performance the potassium atom background
caused by the fuel was continuously monitored in the post-combustion chamber (PCC) for several weeks. A typical concentration
range of 1 ng to 1 μg at STP (800 ppq to 800 ppt; ppq=10-15) was observed. By averaging 100 individual absorption scans the response time was 2.7 s. The minimum detectable absorption
was about 10-4 optical density, corresponding to a detection limit of 4×1011 K atoms/m3 at 1200 K instead of ‘°K’. (K(D2) absorption line; 1.9-m absorption path). This is equivalent to a detection limit of 0.1 ng/m3 at STP or 80 ppq. The fastest response time (0.16 s) was achieved by evaluating single absorption scans. Two combustion facilities
at the Forschungszentrum Karlsruhe (a batch combustor and a 3-MW special waste incinerator with a rotary kiln followed by
a PCC) were investigated. Alkali chlorides were added to the combustion chamber in different forms, of which short spray pulses
of an aqueous salt solution was the method of choice for the residence-time measurement. Flow-time distributions were measured
and the mean residence-time was calculated for various operation conditions. A simultaneous flow-time measurement at two different
locations (8.4 m/17.0 m from the tracer discharge location) was realized with a binary K/Rb tracer and a multi-species spectrometer.
Mean residence-times of (±) 151s and (±) 261s were observed and met the expected values.
Received: 29 April 2002 / Revised version: 21 June 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-6221/5450-50, E-mail: volker.ebert@pci.uni-heidelberg.de
This paper is dedicated to Prof. Dr. Gottfried Huttner on the occasion of his 65th birthday. 相似文献
10.
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
11.
J. Békési S. Szatmári P. Simon G. Marowsky 《Applied physics. B, Lasers and optics》2002,75(4-5):521-524
Applying the combination of a solid-state Ti:Sa laser system and a newly developed wide-aperture, discharge-pumped KrF amplifier,
output pulses with over 9 W average power at 300 Hz have been achieved in a single output beam. The frequency-tripled seed
pulses of the Ti:Sa system – delivering approximately 10 μJ energy at 248 nm – were amplified to over 30 mJ using a 3-pass
off-axis amplification scheme. The optical set-up has been fitted to the amplifier’s parameters, and stored-energy measurements
were carried out with different parameters in order to optimize the operational conditions of the device for the highest average
power.
Received: 10 June 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-551/503-599, E-mail: jbekesi@llg.gwdg.de 相似文献
12.
G. Zhang H. Wang Y. Yu F. Xiong G. Tang W. Chen 《Applied physics. B, Lasers and optics》2003,76(6):677-681
All-optical switching and beam deflection of 2-(2′-hydroxyphenyl) benzoxazole (HBO) in three species of solvent (cyclohexane, ethanol and dimethyl sulfoxide) have been investigated
by using third-harmonic generation (355 nm) of a mode-locked Nd:YAG laser as a pump beam and a continuous-wave He-Ne laser
(632.8 nm) as a probe beam. The nonlinear refractive indices of HBO in different solvents are determined by using the Z-scan
technique. The optical switching and beam-deflection effects are due to the change of the refractive index of HBO under the
pump beam. Through the study of the absorption spectra and the fluorescence spectra of HBO in different solvents, we conclude
that the principal reason for the change of the refractive index of HBO is not the thermal effect because of absorption of
the pump beam, but the excited-state intramolecular proton-transfer (ESIPT) effect of HBO under the pump beam. As the ESIPT
process is very fast, HBO might be an excellent material for high-speed optical switching.
Received: 28 October 2002 / Revised version: 18 March 2003 / Published online: 2 June 2003
RID="*"
ID="*"Corresponding author. Fax: +86-22/2350-1242, E-mail: zhanggl@nankai.edu.cn 相似文献
13.
Mid-infrared trace gas detection using continuous-wave difference frequency generation in periodically poled RbTiOAsO4 总被引:1,自引:0,他引:1
A tunable mid-infrared continuous-wave (cw) spectroscopic source in the 3.4–4.5 μm region is reported, based on difference
frequency generation (DFG) in a quasi-phase-matched periodically poled RbTiOAsO4 (PPRTA) crystal, DFG power levels of 10 μW were generated at approximately 4 μm in a 20-mm long PPRTA crystal by mixing two
cw single-frequency Ti:Al2O3 lasers operating near 713 nm and 871 nm, respectively, using a laser pump power of 300 mW. A quasi-phase-matched infrared
wavelength-tuning bandwidth (FWHM) of ∼12 cm-1 and a temperature tuning rate of 1.02 cm-1/°C were achieved. Experimental details regarding the feasibility of trace gas detection based on absorption spectroscopy
of CO2 in ambient air using this DFG radiation source are also described.
Received: 23 October 2000 / Revised version: 22 January 2001 / Published online: 27 April 2001 相似文献
14.
A. Fix M. Wirth A. Meister G. Ehret M. Pesch D. Weidauer 《Applied physics. B, Lasers and optics》2002,75(2-3):153-163
A pulsed optical parametric oscillator (OPO) with intracavity sum frequency mixing was developed generating energies of up
to 16 mJ in the 281–293 nm wavelength range. Both OPO process and sum frequency mixing are pumped by the harmonics of a single,
medium-sized Nd:YAG laser. The system is characterized by a high overall efficiency (∼4% conversion from 1064 nm to the UV),
a very compact set-up and stable and reliable operation. This system was successfully employed to measure tropospheric ozone
using the differential absorption lidar (DIAL) technique and shows much promise as a lidar transmitter in airborne case studies
as well as in unattended lidar systems for long-term monitoring. An unattended ozone profiling system could already be successfully
realized.
Received: 1 April 2002 / Revised version: 30 May 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-8153/28-1271, E-mail: Andreas.Fix@dlr.de 相似文献
15.
New pump and signal laser sources for difference frequency generation (DFG) at 4 m are described. A laser diode with a 980 nm fiber Bragg grating and a 785 nm Fabry-Perot (FP) laser diode were coupled into an optical fiber and mixed in a periodically poled Mg-doped lithium niobate (PPMgLN ) crystal, resulting in efficient mid-IR DFG. The DFG power was measured to be 0.23 W for a pump power of 5 mW and a signal power of 50 mW with a slope efficiency of 0.92 mW/W2. A Doppler-broadened absorption spectrum of N2O at 2485.2 cm-1 (3.927 m) was observed in a 0.1 m-long gas cell at a pressure of 133 Pa. The spectral linewidth of the DFG source was estimated to be 161 MHz (FWHM) for an averaging time of 700 ms. Real-time monitoring of N2O in a multipass cell with an optical path length of 36 m at a concentration level of 1 ppm was demonstrated. PACS 42.62.Fi; 42.72.Ai; 07.57.Hm 相似文献
16.
K. Song H.K. Cha V.A. Kapitanov Yu.N. Ponomarev A.P. Rostov D. Courtois B. Parvitte V. Zeninari 《Applied physics. B, Lasers and optics》2002,75(2-3):215-227
The results of theoretical and experimental studies and the design of a multi-purpose differential Helmholtz resonant photoacoustic
detector (DHRD) and its applications to high-resolution spectroscopy of molecular gases and gas analysis with a room-temperature
diode laser in the near-IR region are summarized. The series of experiments and numerical analysis of the DHRD sensitivity
were performed for both types (single-pass and multi-pass) of DHRDs within a wide pressure range 0.1–101 kPa, including the
regime of a gas flowing through a DHRD cell. The hardware and electronic arrangement of DHRDs for diode laser spectrometers
and gas analyzers providing a limiting absorption sensitivity better than 10-7 Wm-1 are described. The results of measurements of spectral line parameters of H2O near 800 and 1390 nm and CH4 near 1650 nm (intensities, line broadening and shifting by atomic and molecular gases) are presented and discussed. The problems
and the ways of perfection of the methodology and accuracy of DHRD techniques with tunable diode lasers of near-IR and visible
spectral ranges are discussed.
Received: 1 April 2002 / Revised version: 20 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +7/382-225-8026, E-mail: kvan@asd.iao.ru 相似文献
17.
B. Sumpf T. Kelz M. Nägele H.-D. Kronfeldt 《Applied physics. B, Lasers and optics》1997,64(5):521-524
2 and two diode lasers as pump sources and experiments with this setup are presented. In contrast to the majority of known
applications of the difference frequency mixing with solid state or gas lasers, we apply two single mode diode lasers with
emission wavelengths of 690 nm and 805 nm, respectively. By fixing the emission wavelength of one diode laser and tuning the
wavelength of the second laser, by changing temperature or excitation current, we can cover typically 0.87 cm-1 (FWHM) in good agreement with recently published data and theory. With an input power of 20 mW and 6 mW we achieved an output
power in the nW-range. To demonstrate the capabilities of the spectrometer we scanned CO and OCS absorption lines near 2107 cm-1. From these experiments we deduce an overall signal-to-noise ratio of 1000:1 and a spectral resolution better than 30 MHz.
With such parameters a trace gas detection of CO at sub-ppm level will be possible.
Received: 19 August 1996/Revised version: 5 November 1996 相似文献
18.
The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality
is reported. A continuous-wave (cw), external-cavity tunable diode laser centered at 1.55 μm is used to pump an optical cavity
absorption cell in cw-cavity ringdown spectroscopy (cw-CRDS). Preliminary results are presented that demonstrate the sensitivity,
selectivity and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN and 4.0 ppb for C2H2 are calculated.
Received: 3 April 2002 / Revised version: 3 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-202/994-5873, E-mail: Houston@gwu.edu 相似文献
19.
D. Richter D.G. Lancaster R.F. Curl W. Neu F.K. Tittel 《Applied physics. B, Lasers and optics》1998,67(3):347-350
3 (PPLN) crystal pumped by two single-frequency diode lasers. A maximum DFG power of 1.6 μW at 3.6 μm was generated with a pump
power of 61.4 mW at 832 nm and a signal power of 41.5 mW at 1083 nm incident on a 19-mm-long PPLN crystal, which corresponds
to a conversion efficiency of 335 μW W-2 cm-1.
Received: 16 June 1998 相似文献
20.
V.G. Savitski A.M. Malyarevich K.V. Yumashev B.D. Sinclair A.A. Lipovskii 《Applied physics. B, Lasers and optics》2003,76(3):253-256
Diode-pumped Nd:YVO4 and Nd:KGW lasers passively Q-switched with PbS-quantum dot-doped phosphate glass were demonstrated. For the Nd:YVO4 laser, pulses 110 ns in duration with a 13% Q-switching efficiency were obtained. The absorption recovery time of the PbS-doped
glass was measured to be 27±4 ps. Some recommendations for more efficient use of PbS-doped glasses for Q-switching of diode-pumped
lasers are suggested on the basis of our analysis.
Received: 29 July 2002 / Revised version: 18 September 2002 / Published online: 12 February 2003
RID="*"
ID="*"Corresponding author. Fax: +375-17/232-6286, E-mail: savitski@eudoramail.com 相似文献