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1.
We present a high-power and narrow-linewidth laser for intercombination magneto-optical trapping of ytterbium (Yb) atoms using
the 6s2
1S0–6s6p 3P1 transition. The system generates 415 mW of continuous wave laser radiation at 556 nm with a linewidth of less than 100 kHz.
It is based on a commercial 1 W fiber laser with a frequency doubling stage. Up to 58% frequency doubling efficiency is obtained
at an input power of 0.5 W by using a lithium triborate crystal as a nonlinear medium. The system has been successfully used
for laser cooling of Yb atoms.
PACS 42.55.Wd; 42.60.By; 42.79.Nv 相似文献
2.
We present detailed investigations of a femtosecond green-pumped optical parametric oscillator (OPO) based on lithium triborate.
As pump source, a frequency-doubled Yb-fiber laser-amplifier system is used. The OPO generates signal pulses tunable over
a spectral range from 780 to 940 nm and idler pulses tunable from 1630 to 1190 nm. More than 250 mW are generated in the signal
beam and more than 300 mW in the idler beam. Without dispersion compensation chirped signal pulses with a pulse duration between
100 and 250 fs are measured. Using this system for coherent anti-Stokes Raman scattering spectroscopy, vibrational resonances
between 1110 and 6760 cm−1 can be excited. Due to the chirped pulses, a spectral resolution of 100 cm−1 is achieved, which is 2.5 times higher compared to an excitation with time-bandwidth limited pulses. 相似文献
3.
G. Durry N. Amarouche L. Joly X. Liu B. Parvitte V. Zéninari 《Applied physics. B, Lasers and optics》2008,90(3-4):573-580
The 2.7 μm spectral range is highly suitable for the in situ monitoring of atmospheric H2O using compact balloonborne laser diode spectrometers. Water vapour spectroscopic parameters of the 202
101 and the 413
414 transitions of the ν3 band are revisited in this spectral region using a new distributed-feedback InGaAsSb laser diode emitting at 2.63 μm. Accurate
line strengths are provided which are well adapted for the in situ probing of the middle atmosphere. Our measurements are
thoroughly compared to an existing molecular database, laboratory measurements and ab-initio calculations. A laser hygrometer
was developed for operation from small stratospheric balloons using this new laser diode technology, with emission at 2.6 μm.
The realized sensor is described and results from a recent test-flight are reported.
PACS 07.57.Ty; 92.60 Jq 相似文献
4.
Fluorescence of the S1→S0 transition of 1,2,4-trimethylbenzene vapour after laser excitation at 266 nm was investigated in a heated cell. Experiments
were performed for temperature between 350 and 900 K, at pressure between 0.1 and 3.0 MPa and for oxygen molar fraction between
0 and 21%. The absorption cross section was found to reduce by about 20% between 350 and 900 K. 1,2,4-trimethylbenzene fluorescence
exponentially decreased by three orders of magnitude as temperature increased. A similar behaviour was observed with pressure,
although fluorescence reduced only by a factor of 2.5 between 0.1 and 3.0 MPa. Additionally, Stern–Volmer plots were found
to be linear for temperatures between 450 and 750 K. Using the dependence of 1,2,4-trimethylbenzene fluorescence on temperature,
potential use of this molecule for temperature measurements in turbulent flows is suggested. 相似文献
5.
Song Mao Ma Wen-Gan Zhang Ren-You Guo Lei Wang Shao-Ming 《The European Physical Journal C - Particles and Fields》2009,59(4):761-768
Higgs-boson production in association with a W-boson pair at e
+
e
− linear colliders is one of the important processes in probing the coupling between the Higgs boson and vector gauge bosons
and discovering the signature of new physics. We describe the impact of the complete electroweak (EW) radiative corrections
of
to this process in the standard model (SM) at the International Linear Collider (ILC), and investigate the dependence of the
lowest-order (LO) and EW next-to-leading order (NLO) corrected cross sections on the colliding energy
and the Higgs-boson mass. The LO and NLO EW corrected distributions of the invariant mass of the W-boson pair and the transverse
momenta of the final W-boson and Higgs boson are presented. Our numerical results show that the relative EW radiative correction
(δ
ew) varies from −19.4% to 0.2% when m
H=120 GeV and
grows from 300 GeV to 1.2 TeV. 相似文献
6.
Kenji Mohri 《Communications in Mathematical Physics》1999,202(3):669-699
We develop a method to analyze systematically the configuration space of a D-brane localized at the orbifold singular point
of a Calabi–Yau d-fold of the form ℂ
d
/Γ using the theory of toric quotients. This approach elucidates the structure of the K?hler moduli space associated with
the problem. As an application, we compute the toric data of the Γ-Hilbert scheme.
Received: 9 June 1998 / Accepted: 18 November 1998 相似文献
7.
Based on the configuration-space generating functional of the Green functions for the gauge-invariant system in higher-order
derivatives theories, the equations of the transformation properties at the quantum level have been derived. It follows that
the sufficient conditions are found which implies that there exists the conservation laws and the expressions of the quantal
conserved laws are also given. Applying the results to the non-Abelian Chern-Simons higher-order derivatives theories, the
quantal BRST conserved charge and other conserved charges are found, the transformation properties of the conformal transformation
at the quantum level is discussed, the quantal conserved angular momentum is derived, it is pointed out that fractional spin
in this system may be also preserved in quantum theories. But the connection between the symmetries and conservation laws
in classical theories are not always preserved in quantum theories. 相似文献
8.
Jobin K. Antony Gurneesh Singh Jatana Nilesh J. Vasa V. L. N. Sridhar?Raja A. S. Laxmiprasad 《Applied Physics A: Materials Science & Processing》2010,101(1):161-165
Laser Induced Breakdown Spectroscopy (LIBS) can be considered as a prominent technology for compositional analysis of materials
in low-pressure space applications. In space applications, usually LIBS is conducted in a low-pressure environment and proper
understanding of the plasma parameters is significant for any improvement in the system. A model is developed to describe
the heating and subsequent melting, vaporization and ionization of a target material during LIBS process. A numerical model
based on one-dimensional thermal conductivity equation is being used to simulate the target evaporation and a hydrodynamic
model is used to simulate plume expansion. Further, an experimental approach of measuring spectral emission from the ablation
plume using emission spectroscopy and estimating the plasma state, such as the ionization species, and average plasma temperature,
is investigated. An important result of this work is that for different ambient conditions, laser ablation plume dynamics
can be estimated. 相似文献
9.
C.P. Wyss W. Lüthy H.P. Weber V.I. Vlasov Y.D. Zavartsev P.A. Studenikin A.I. Zagumennyi I.A. Shcherbakov 《Applied physics. B, Lasers and optics》1999,68(4):659-661
4 as a host for neodymium has several advantages for diode pumping in comparison with other crystals. The absorption cross
section of neodymium in GdVO4 is considerably stronger and broader than in YAG. This allows for the construction of very compact monolithical microchip
lasers. In our paper, we report for the first time on a diode-pumped monolithical Nd3+([%at.]1.3):GdVO4 microchip laser at 1.06 μm. A maximum output power of 5 W is achieved. The temporal and the spectral emission properties
are described. The beam propagation properties are studied in detail.
Received: 23 July 1998 / Revised version: 9 November 1998 / Published online: 24 February 1999 相似文献
10.
Nobuo Ueno Satoshi Kera Kazuyuki Sakamoto Koji. K. Okudaira 《Applied Physics A: Materials Science & Processing》2008,92(3):495-504
This article describes the origins of the width of the highest occupied molecular orbital (HOMO) state observed in the ultraviolet
photoemission spectra (UPS) of thin organic semiconductor films. Although much research has been performed on the electrical
properties of organic devices, a lot of crucial problems still remain. Among these problems, the charge mobility in organic
semiconductor systems is one the most important subjects to be elucidated. In order to discuss the mobility, it is essential
to understand both the intermolecular interaction and the electron-molecular vibration coupling. Experimental measurements
of the energy band dispersion give information about the intermolecular interaction, and experimental detection of the HOMO
hole-vibration coupling is indispensable to comprehend impacts of the electron-vibration coupling on the hole transport. Since
most of the information is hidden behind the finite bandwidth of the HOMO, only careful UPS measurements can provide information
on these important phenomena related to charge carrier dynamics. In this article, we summarize our recent challenges on UPS
measurements of organic thin films, which give the band dispersion of the HOMO and the HOMO hole-vibration coupling, and discuss
the origins of the UPS bandwidth that relates to the charge carrier dynamics. 相似文献
11.
Theophilos Maltezopoulos Manuel Mittenzwey Armin Azima Jörn Bödewadt Hatem Dachraoui Marie Rehders Christoph Lechner Michael Schulz Marek Wieland Tim Laarmann Jörg Roßbach Markus Drescher 《Applied physics. B, Lasers and optics》2014,115(1):45-54
Direct seeding with a high-harmonic generation (HHG) source can improve the spectral, temporal, and coherence properties of a free-electron laser (FEL) and shall reduce intensity and arrival-time fluctuations. In the seeding experiment sFLASH at the extreme ultraviolet FEL in Hamburg FLASH, which operates in the self-amplified spontaneous emission mode (SASE), the 21st harmonic of an 800 nm laser is refocused into a dedicated seeding undulator. For seeding, the external light field has to overcome the noise level of SASE; therefore, an efficient coupling between seed pulse and electron bunch is mandatory. Thus, an HHG beam with a proper divergence, width, beam quality, Rayleigh length, pointing stability, single-shot pulse energy, and stability in the 21st harmonic is needed. Here, we present the setup of the HHG source that seeds sFLASH at 38.1 nm, the optimization procedures, and the necessary diagnostics. 相似文献
12.
Anne Sickles 《The European Physical Journal C - Particles and Fields》2009,61(4):583-588
These proceedings review recent results from two and three particle correlations in heavy ion collisions. In particular we
discuss the modified structure of the away side jet correlations. Under the assumption that the away side can be decomposed
into a punch through component at Δ
φ=π and a shoulder component with a peak displaced from π many similar properties are observed between the ridge and shoulder. The particle ratios, yields and p
T
spectra are in near agreement. We also highlight important future measurements, including investigating if the decomposition
of the away side jet correlations remains reasonable with high p
T
triggers and technical improvements to the extraction of jet induced correlations. 相似文献
13.
N. G. C. Astrath F. B. G. Astrath J. Shen J. Zhou C. E. Gu L. C. Malacarne P. R. B. Pedreira A. C. Bento M. L. Baesso 《Applied physics. B, Lasers and optics》2009,94(3):473-481
A complete theoretical model is presented for the thermal mirror technique under top-hat laser excitation. Considering the
attenuation of the top-hat excitation laser intensity along the thickness of a sample due to its optical absorption coefficient,
we calculate the laser-induced temperature and surface deformation profiles. A simplified theoretical model for a high absorption
sample is also developed. The center intensity of a probe beam reflected from the thermal mirror at a detector plane is derived.
Numerical simulation shows that the thermal mirror under the top-hat laser excitation is as sensitive as that under Gaussian
laser excitation. With top-hat laser excitation, the experimental results of thermo-physical properties of opaque samples
are found to be well consistent with literature values, validating the theory. 相似文献
14.
C. L. Sones K. S. Kaur P. Ganguly D. P. Banks Y. J. Ying R. W. Eason S. Mailis 《Applied Physics A: Materials Science & Processing》2010,101(2):333-338
We propose a rapid prototyping method for the fabrication of optical waveguides based on the direct laser-printing method
of ultrafast Laser-Induced Forward Transfer (LIFT) followed by further processing. The method was implemented for the fabrication
of titanium in-diffused lithium niobate channel waveguides and X-couplers by LIFT-depositing titanium metal followed by diffusion.
Propagation loss as low as 0.8 dB/cm was measured in preliminary experiments. 相似文献
15.
In this work, the Raman scattering of melamine was studied under high pressure up to 60 GPa. The behavior of the most intensive peaks of the Raman spectrum of melamine, 677 cm?1 and 985 cm?1 modes, and their line widths do not show any phase transition or indication of formation of sp 3 bonds. Comparing the behavior of the line width of the Raman peaks of graphite under pressure and that of melamine leads us to conclude that the s-triasine (C–N) ring is more rigid than the C–C graphite ring. High pressure results with melamine suggest that the direct phase transition g-C3N4 to dense C3N4 phase should occur above 60 GPa. 相似文献
16.
T.-S. Kim H. Park K. Ko G. Lim Y.-H. Cha J. Han D.-Y. Jeong 《Applied physics. B, Lasers and optics》2010,100(2):437-442
Currently, the nuclear industry needs strongly a reliable detection system to continuously monitor a coolant leak during a
normal operation of reactors for the ensurance of nuclear safety. In this work, we propose a new device for the coolant leak
detection based on tunable diode laser spectroscopy (TDLS) by using a compact diode laser. For the feasibility experiment,
we established an experimental setup consisted of a near-IR diode laser with a wavelength of about 1392 nm, a home-made multi-pass
cell and a sample injection system. The feasibility test was performed for the detection of the heavy water (D2O) leaks which can happen in a pressurized heavy water reactor (PWHR). As a result, the device based on the TDLS is shown
to be operated successfully in detecting a HDO molecule, which is generated from the leaked heavy water by an isotope exchange
reaction between D2O and H2O. Additionally, it is suggested that the performance of the new device, such as sensitivity and stability, can be improved
by adapting a cavity enhanced absorption spectroscopy and a compact DFB diode laser. We presume that this laser-based leak
detector has several advantages over the conventional techniques currently employed in the nuclear power plant, such as radiation
monitoring, humidity monitoring and FT-IR spectroscopy. 相似文献
17.
Y. He M. Kono R. T. White M. J. Sellars K. G. H. Baldwin B. J. Orr 《Applied physics. B, Lasers and optics》2010,99(4):609-612
A chirp-minimized, nanosecond-pulsed system has been developed to generate tunable coherent ultraviolet light at ∼212.5 nm
by fourth-harmonic conversion of output from an amplified, injection-seeded optical parametric oscillator (OPO). Our CHAPS
(coherent heterodyne-assisted pulsed spectroscopy) method is used to characterize the frequency stability and optical bandwidth
of the system’s output radiation by recording sub-Doppler two-photon excitation spectra of krypton. In our new scanned-reference
variant of CHAPS, the central frequency for each amplified OPO pulse is logged by the optical-heterodyne chirp-analysis software,
with the frequency of the seed laser slowly tuned and monitored by a high-resolution wavemeter, unlike our previous implementation
of CHAPS where the seed-laser frequency was fixed. For the amplified, up-converted pulses at ∼212.5 nm, our CHAPS measurements
indicate an optical bandwidth of ∼100 MHz, consistent with the Fourier-transform limit of their duration (∼4.5 ns). 相似文献
18.
The visible fluorescence spectrum of single flavoprotein at a temperature of 1.5 K has been measured by one-photon excitation. The flavoprotein studied was a photoswitchable enzyme, photoactivated adenylyl cyclase. The time course of the spectrum revealed a structural change occurring at a rate of 10(-3) s(-1) around hydrogen bonds at the flavin cofactor binding site. 相似文献
19.
We report direct absorption spectroscopic detection of ozone at ambient pressure with a pulsed, DFB quantum-cascade laser (QCL) tuned within 1044–1050 cm-1 by temperature scanning. Wavelength calibration curves were derived from FTIR and CO2 spectra and interpreted with respect to the heat transfer from the heterostructure to the sink. The laser linewidth (0.13 cm-1 FWHM) was found to decrease with temperature, probably as a result of operation at constant current. Spurious spectral features due to baseline inaccuracies were successfully filtered out from the QCL O3 spectra using differential absorption. Reference O3 concentrations were obtained by applying the same method to UV spectra, simultaneously measured with a differential optical absorption spectrometer (DOAS). Column densities retrieved from QCL spectra are in fairly good agreement (±20%) with the DOAS values above 28 ppmm. The estimated QCL lowest detectable, absolute and differential absorptions, (7×10-3 and 2×10-3, respectively), entail effective detection limits of 14 and 25 ppmm, respectively. Ongoing improvements in the acquisition system should allow the achievement of detection limits at the level of commercial open-path DOAS systems (2 ppmm) in the near future. Our results demonstrate the applicability of the differential absorption method to QCL spectroscopy at ambient pressure, and encourage its use for open path detection. PACS 42.62.Fi; 82.80.Gk; 92.60.Sz 相似文献
20.
The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser (PKU-FEL) facility is carried out. In order to minimize the scale of the cryogenic system and the running cost, the superconducting accelerator and the superconducting injector will mainly run at a long-pulsed mode. Optimization of the 2-K cryogenic system is carried out based on the heat load estimation and running parameters. Total cooling power of 52.5 W for the long-pulsed mode is necessary for the PKU cryogenic system. The PKU cryogenic system will be the first 2-K system for accelerators in China and will provide experience for similar facilities. 相似文献