共查询到20条相似文献,搜索用时 0 毫秒
1.
Panayiotis Nikolaou Nicholas Whiting Neil A. Eschmann Kathleen E. Chaffee Boyd M. Goodson Michael J. Barlow 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2009,197(2):249-254
Volume holographic gratings (VHGs) can be exploited to narrow the spectral output of high-power laser-diode arrays (LDAs) by nearly an order of magnitude, permitting more efficient generation of laser-polarized noble gases for various applications. A 3-fold improvement in 129Xe nuclear spin polarization, PXe, (compared to a conventional LDA) was achieved with the VHG-LDA’s center wavelength tuned to a wing of the Rb D1 line. Additionally, an anomalous dependence of PXe on the xenon density within the OP cell is reported—including high PXe values (>10%) at high xenon partial pressures (1000 torr). 相似文献
2.
Y. Arimoto T. InoH.M. Shimizu T. KamiyamaH. Kira T. OkuY. Sakaguchi K. KakuraiK. Sakai J. SuzukiS. Koizumi M. AraiY. Endo M. NakamuraT. Shinohara M. TakedaS. Wakimoto D. YamazakiK. Ohoymama H. HirakaK. Yamada K. TsutsumiL.-J. Chang 《Physica B: Condensed Matter》2011,406(12):2439-2442
Polarized neutron spin filters are being developed based on spin-exchange optical pumping. In the present study a high-power diode laser (85 W) was used to excite Rb atoms and the laser linewidth was narrowed using an external cavity. The optics in the external cavity were designed by ray tracing. The ray-trace calculations demonstrated that a doublet lens in front of the laser eliminates aberrations. The maximum spectral peak height in the doublet optics was found to be 25% higher than for a singlet lens. 相似文献
3.
The mode-hop behavior and the power characteristics of a laser diode with wavelength-selective optical feedback are experimentally
investigated. The feedback is provided by external volume holographic gratings, also called ‘Bragg mirrors’, at normal incidence.
We demonstrate that a Bragg mirror forces a laser diode to operate only within a narrow wavelength range, and that the emission
wavelength of the laser diode is stabilized against variations of the injection current. Moreover, we present periodic undulations
of the power characteristics of the laser, depending on the driving current. They can be qualitatively explained with a simple
model which takes into account that the threshold gain in the laser system strongly depends on the wavelength. 相似文献
4.
Ruifeng Kan Wenqing Liu Yujun Zhang Jianguo Liu Min Wang Dong Chen Jiuying Chen Yiben Cui 《中国光学快报(英文版)》2007,5(1)
Tunable diode laser absorption spectroscopy (TDLAS) has been widely employed in atmospheric trace gases detection. In the measurement of these trace gases, harmonic detection combined with a multi-pass white cell could remarkably enhance the detection sensitivity. In this paper, a portable TDLAS system built specifically for long time monitoring methane in the atmosphere is introduced. The detection limit is below 100 ppb that is enough for the monitoring of ambient methane, and the long time monitoring results obtained in Beijing are given, which is well coincident with that of the Fourier transform infrared (FTIR) spectroscopy. 相似文献
5.
Development and characterization of Yb-Er laser glass for high average power laser diode pumping 总被引:5,自引:0,他引:5
G. Karlsson F. Laurell J. Tellefsen B. Denker B. Galagan V. Osiko S. Sverchkov 《Applied physics. B, Lasers and optics》2002,75(1):41-46
A new strong erbium laser glass (SELG) based on a boro-alumo-phosphate composition is reported. We discuss the synthesis and
chemical properties together with spectroscopic and thermo-mechanical data. The new glass composition shows excellent laser
performance and withstands high-average power pump radiation. We present laser results at 1.54 μm from flashlamp and laser
pumping. In tests with laser-diode pumped Q-switched Er-Yb microchip lasers, we have achieved up to 150 mW of average output
power and generated 1.2 kW in peak power. Co2+:MgAl2O4 was here used as the saturable absorber.
Received: 21 December 2001 / Revised version: 14 April 2002 / Published online: 8 August 2002 相似文献
6.
C. Roller A. Fried J. Walega P. Weibring F. Tittel 《Applied physics. B, Lasers and optics》2006,82(2):247-264
A tunable diode laser absorption spectroscopy (TDLAS) instrument was deployed onboard a DC-8 aircraft as part of the International
Chemical Transport Experiment – North America (INTEX-NA) during the summer of 2004 to quantify atmospheric formaldehyde (CH2O) concentrations. A number of improvements, both software and hardware, are discussed and include the laser tuning waveform,
spectral wavelength centering, and optical stabilization. In addition, the impact of perturbations to the instrument in flight
is reviewed and a number of advanced TDLASdata-acquisition and processing concepts are introduced to identify the presence
of optical perturbations in flight to objectively eliminate such perturbed data, assess the validity of the fitting routine
in the presence of perturbed data, provide various diagnostic measures to elucidate system behavior, and assess the efficacy
of various opto-mechanical improvements implemented to reduce the magnitude of such perturbations. The concepts specific to
our TDLASmeasurements of CH2O should have broader and more universal applicability to measurement of other trace gases and possibly other methods of detection. 相似文献
7.
In this investigation, we propose and investigate the simple self-injection locked Fabry-Perot laser diodes (FP-LDs) in optical line terminal (OLT); and wavelength-tunable optical network unit (ONU) using reflective optical semiconductor amplifier (RSOA) and FP-LD laser for downstream and upstream traffic in long reach (LR) wavelength division multiplexed-passive optical network (WDM-PON) respectively. The output performance of the proposed two laser sources in terms of power and side-mode suppression ratio (SMSR) has been discussed. Here, for the downstream traffic, the proposed optical transmitter can be directly modulated at 2.5 Gb/s on-off keying (OOK) format with nearly 0.4 dB power penalty at bit error rate (BER) of 10−9 through 75 km single-mode fiber (SMF) transmission. Moreover, the proposed upstream transmitter can be directly modulated at 1.25 and 2.5 Gb/s with nearly 0.5 and 1.1 dB power penalty, respectively, at the BER of 10−9. 相似文献
8.
A laser absorption spectrometer is described which employs a wavelength tunable diode laser in conjunction with a multipass White cell. The instrument uses absorption lines in the
3 band of SO2 to monitor atmospheric SO2 concentrations with sensitivities as high as 0.2 parts per billion (ppb) in a laboratory system. A portable instrument with a fast response time and a sensitivity of 1 ppb is described, and the development of a highly practical field instrument, based on pyroelectric detectors, is discussed.Work supported by the Department of National Health and Welfare, Environment Canada, Ontario Ministry of the Environment, and Atmospheric Service, Environment Canada. 相似文献
9.
E. Stoltz M. Meyerhoff N. Bigelow M. Leduc P. -J. Nacher G. Tastevin 《Applied physics. B, Lasers and optics》1996,63(6):629-633
New diode lasers delivering 50 mW output power at 1083 nm are shown to be efficient sources for optical pumping of helium. They can polarize nuclei in a3He gas up toM = 50% over the pressure range 0.4–1.6 torr. Larger nuclear polarizationsM of3He nuclei, of order 80%, can be obtained in3He-4He mixtures when the laser frequency is tuned to a4He line. A standard optical measurement of nuclear polarizationM has been extended to the case of3He-4He mixtures. The effect of various parameters on the steady-state polarizationM and on the pumping timeT
p is discussed.Laboratoire associé au Centre National de la Recherche Scientifique et à l'Université P. M. Curie 相似文献
10.
New designs for gas cells are presented that incorporate transmissive or reflective optical diffusers. These components offer
simple alignment and can disrupt the formation of optical etalons. We analyse the performance–limiting effects in these cells
of random laser speckle (both objective and subjective speckle), interferometric speckle and self-mixing interference, and
show how designs can be optimised. A simple, single pass transmissive gas cell has been studied using wavelength modulation
spectroscopy to measure methane at 1651 nm. We have demonstrated a short-term noise equivalent absorbance (NEA, 1σ) of 2×10−5, but longer term drift of up to 3×10−4 over 22 hours. 相似文献
11.
Ludlow AD Huang X Notcutt M Zanon-Willette T Foreman SM Boyd MM Blatt S Ye J 《Optics letters》2007,32(6):641-643
We demonstrate phase and frequency stabilization of a diode laser at the thermal noise limit of a passive optical cavity. The system is compact and exploits a cavity design that reduces vibration sensitivity. The subhertz laser is characterized by comparison with a second independent system with similar fractional frequency stability (1x10(-15) at 1 s). The laser is further characterized by resolving a 2 Hz wide, ultranarrow optical clock transition in ultracold strontium. 相似文献
12.
R. Le Harzic D. Breitling M. Weikert S. Sommer C. Föhl F. Dausinger S. Valette C. Donnet E. Audouard 《Applied Physics A: Materials Science & Processing》2005,80(7):1589-1593
The effect of varying fluence for laser microprocessing of Al and Cu is studied at a pulse duration of 120 fs at atmospheric pressure. For low fluences (<2 J/cm2) quality is relatively good for both metals but completely melt free processing does not seem to be possible. For fluences above 2 J/cm2, a huge difference is observed between Al and Cu. Important roughness and clear evidence for remelted and recast matter solidified like spikes, as well as significant burrs at the edge are observed for Al. In the case of Cu the micromachining quality is high, with practically no redeposit matter and low roughness in the bottom of the groove. An analysis is given in terms of processes of a thermal nature underlining the role of electron-phonon coupling. The existence of an optimal point for micromachining is also evidenced. PACS 79.20.Ds; 42.62.Cf; 81.65.Cf 相似文献
13.
We report the experimental results of frequency-selective laser optical pumping and spin exchange of Cs with129Xe and131Xe in a high magnetic field of 11.74 T. Our results show that hyperpolarized129Xe and131Xe nuclear magnetic resonance (NMR) signals exhibit alternating phases when the laser frequency for pumping the cesium atoms is changed, which is explained on the basis of the high-field optical pumping of Cs. We obtain about 3% polarization of the129Xe. The electron-spin polarization of the Cs atoms has been measured to be about 22% with a simple NMR method. 相似文献
14.
Keiichi Nagai Kentarou Kawaguchi Chikashi Yamada Kazuo Hayakawa Yoshihiro Takagi Eizi Hirota 《Journal of Molecular Spectroscopy》1980,84(1):197-203
We construct a high-precision wavelength meter for infrared tunable diode lasers (TDL) which consists of moving corner reflectors forming a Michelson interferometer, with a single-frequency HeNe laser as a standard. The design of the wavelength meter is described in detail, and possible sources of errors are discussed. An absolute accuracy of 10?7 is demonstrated by measuring CO2 laser wavelengths and almost the same order of accuracy is achieved by applying the wavelength meter to the ν1 band of N2O observed by a TDL. 相似文献
15.
We report and evaluate a novel double-end polarised 880?nm pumping scheme for a Nd:GdVO4 self-Raman laser, aimed at efficiently generating high output powers in the near-infrared and visible. Compared to conventional single-end pumping, this pump scheme has significant benefits in terms of absorption efficiency, temperature effects in the crystal, and mode-matching between the pumping beam and TEM00 resonator mode. The maximum first-Stokes output powers were 4.1?W for CW operation and 5.63?W for quasi-CW (50?% duty-cycle) operation, with the diode-Stokes conversion efficiency of 11.2?% and 10.3?%, respectively. Visible emission was also realised by intra-cavity frequency-doubling (586.5?nm) or sum-frequency-generation (559?nm) using BBO or LBO crystals. For CW operation, the maximum output power was 3.46?W at 586.5?nm and 4.05?W at 559?nm, with diode-visible conversion efficiency of 10.7?% and 12.5?%; while for quasi-CW operation (50?% duty-cycle), the maximum output peak power was 6.5?W at 586.5?nm and 9.2?W at 559?nm, corresponding to 13.1?% and 18.9?% diode-visible conversion efficiency. 相似文献
16.
K. Dorenburg M. Gladisch G. zu Putlitz 《Zeitschrift für Physik A Hadrons and Nuclei》1979,289(2):145-149
The hyperfine structure (hfs) density and temperature shift has been measured for several alkalies K, Rb, and Cs against the noble gas collision partners He, Ne and Ar at buffer gas densities up to 26000 Torr. The measured shifts have been fitted by an expression dependent on density and temperature yielding as a main new result the quadratic hfs density shift coefficients. 相似文献
17.
M. Scotoni A. Rossi D. Bassi R. Buffa S. Iannotta A. Boschetti 《Applied physics. B, Lasers and optics》2006,82(3):495-500
Spectral investigation around 6115 cm-1 for simultaneous detection of ammonia, methane and ethylene in gas samples is presented. Experimental data on the ν2+ν3+ν4 combination band of ammonia are reported with a resolution of 1.5 GHz. A trace gas analyzer based on a resonant photoacoustic
cell and an external cavity diode laser has been used for detection. A data fitting procedure has been developed in order
to improve the system sensitivity and to limit the need of a reference cell. The selected spectral region allows a sensitivity
of about 60 ppm for ammonia, 6 ppm for methane and 30 ppm for ethylene with 0.3 mW laser power. An application of simultaneous
detection of such molecules in a mixture reproducing their typical abundances in real gas samples from biomass gasification
is discussed.
PACS 42.62.Fi; 42.55.Px; 82.80.Ch 相似文献
18.
We applied a VHG-FAC lens in our design in this work to collimate the fast axis and lock the output spectrally. We used a beam shaping technique to improve the beam symmetry and power density of a high power diode laser stack with a stripe mirror plate, a V-Stack mirror and polarization beam combining elements. By this technique, the beam of a high power diode laser stack is effectively coupled into a standard 365 μmcore diameter and a NA = 0.22 fiber. By this technique, compactness, higher efficiency, narrower spectral line width and lower production cost of the diodes are possible. 相似文献
19.
S. Chakrabarti B. Ray P. N. Ghosh 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):359-368
The effects of a strong control or pump laser, counter propagating
or copropagating with the probe beam, on the probe absorption spectra of
85Rb and 87Rb-D2 transitions have been investigated inside
a room temperature Rb vapour cell. In both cases a set of strong velocity
selective resonance dips are observed at different velocities. Their
movements across the Doppler broadened probe absorption profile have been
studied for different lock frequencies of the control laser. These spectra
are modified by optical pumping effects due to the presence of another
hyperfine component of the ground state. A repumping laser, from the dark
hyperfine component of the ground level transfers almost 75% of the atoms
from the dark state to the pump probe cycle hence reducing the optical
pumping effect. A numerical simulation is done to explain the observed
spectra. The effect of a control laser on the Lamb dip spectrum of the probe
laser has also been investigated. The control beam is used to improve the
strength of a weak hyperfine dip on the Doppler broadened probe spectrum.
The strength of the hyperfine dip increases by a factor of 3.2 in presence
of the control laser. The observed dips show that pump-probe spectroscopy
can be used as velocity selectors of atoms. 相似文献
20.
The performance of a tunable diode laser (DL) spectrometer is directly determined by the DL qualities and its tunability control. Emission characteristics are very sensitive to current and temperature drifts. In order to obtain a high quality source for spectroscopy, we designed our own liquid nitrogen cryostat containing the DL. Moreover we compared current and temperature control and we found that temperature tuning can be more efficient. We check and demonstrate it by recording SO2 spectra in the 1168–1169 cm–1 spectral region. 相似文献