共查询到20条相似文献,搜索用时 15 毫秒
1.
R.A. Ganeev R.I. Tugushev A.A. Ishchenko N.A. Derevyanko A.I. Ryasnyansky T. Usmanov 《Applied physics. B, Lasers and optics》2003,76(6):683-686
We investigated nonlinear refraction, nonlinear absorption, and saturable absorption of polymethine dyes by the Z-scan technique
(λ=1064 nm). The analysis of simultaneous appearance of several nonlinear optical processes in dye solutions excited by picosecond
pulses was carried out. The saturable absorption was analyzed taking into account various models. Nonlinear refractive indices,
nonlinear absorption coefficients, and saturation intensities of various polymethine dyes were measured.
Received: 27 December 2002 / Revised version: 6 March 2003 / Published online: 5 May 2003
RID="*"
ID="*"Corresponding author. Fax: +81-471/363-366, E-mail: r_ganeev@issp.u-tokyo.ac.jp
RID="**"
ID="**"Present address: The Institute for Solid State Physics, The Tokyo University, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581,
Japan 相似文献
2.
L. Nedelchev L. Nikolova A. Matharu P.S. Ramanujam 《Applied physics. B, Lasers and optics》2002,75(6-7):671-676
A study of the propagation of elliptically polarized light and the resulting formation of macroscopic chiral structures in
a series of azobenzene side-chain copolyesters, in which the morphology is varied from liquid crystalline to amorphous, is
reported. Real-time measurements are presented, showing the dynamic behavior of the photoinduced rotation of the polarization
ellipse in the different samples. The relationship between the ellipticity of the recording light and the linear birefringence
induced is studied. A numerical solution that takes into account the influence of the photoinduced linear dichroism on the
light propagation through the samples is presented.
Received: 10 June 2002 / Revised version: 26 July 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +45-4677/4588, E-mail: lian.nedelchev@risoe.dk
RID="**"
ID="**"Permanent address: Department of Chemistry and Physics, The Nottingham Trent Unversity, Clifton Lane, Nottingham NG11 8NS,
England 相似文献
3.
Fourier transform of an amplitude modulated data page gives rise to high intensity at the zero-spatial frequency. Recording such high intensity requires a large-dynamic range on the part of the recording material and leads to material saturation. Moving the recording plane away from the Fourier plane is often used for spectrum uniformity and thereby improving the quality of reconstruction. In the present paper, we have investigated the effect of photopolymer material saturation on the bit-error-rate, the signal-to-noise ratio, and content-addressable search of a holographic data storage system. We have performed numerical simulation of the process of hologram recording and corresponding reconstruction, and show an improvement in the BER and the SNR values of the reconstructed data page for the defocused recording. A multi-layer thin-slice approach to take into account the thickness of recording material is used to simulate the volume hologram. The numerical simulation model can be used as an efficient tool for system optimization. 相似文献
4.
5.
R.A. Pérez F. Dyment G. García Bermúdez D. Abriola M. Behar 《Applied Physics A: Materials Science & Processing》2003,76(2):247-250
The diffusion of Ta in the hcp (α) phase of high-purity Ti (99.99%) was studied at different temperatures from 911 K up to
1123 K. The Rutherford Backscattering Spectrometry (RBS) and Heavy Ion RBS (HIRBS) techniques were used to obtain the penetration
profiles. The evolution of the diffusion coefficient, D, as a function of temperature follows prediction of the Arrhenius
law. The activation energy of the diffusion process is (318±7)kJ/mol, similar to that corresponding to self-diffusion in α-Ti.
On the other hand, the measured values of D are systematically lower than those corresponding to self-diffusion by a factor
of approximately 5. This reduction could be explained by taking into account the mass difference between Ta and Ti. An increase
of the diffusion coefficient was measured when the diffusion proceeds on a less pure Ti (99.9%) matrix. This increment is
higher at lower temperatures.
Received: 12 November 2001 / Accepted: 12 March 2002 / Published online: 5 July 2002
RID="*"
ID="*"
RID="*"
ID="*"
RID="**"
ID="**"Corresponding author. Fax: +54-11/6772-7362, E-mail: dyment@cnea.gov.ar
RID="*"
ID="*"Members of the Carrera del Investigador Científico del Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET),
Argentina 相似文献
6.
An improved model for pure rotational coherent anti-Stokes Raman scattering (CARS) has been developed for the dual-broadband
approach. This model takes into account the fact that coherent anti-Stokes as well as Stokes radiation are generated simultaneously,
and these two branches overlap and interact at high pressures giving rise to an inter-branch interference effect. In combustion
studies, the anti-Stokes branch is used to determine temperature and concentrations of key species, of which nitrogen is the
most widely used, and we have found that the interference effect on the anti-Stokes side is of such magnitude that it clearly
needs to be taken into account at pressures of a few MPa. The necessary modifications to the total third-order susceptibility
are presented and a derivation of the convolution integral for a finite-bandwidth pump source is given.
Received: 18 February 2002 / Revised version: 9 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +46-46/2224542, E-mail: mikael.afzelius@forbrf.lth.se 相似文献
7.
D. Stifter P. Burgholzer O. Höglinger E. Götzinger C.K. Hitzenberger 《Applied Physics A: Materials Science & Processing》2003,76(6):947-951
Optical coherence tomography (OCT) is a relatively new imaging technique capable of recording cross-sectional images of transparent
and turbid structures with micrometer-scale resolution. Originally developed for biomedical imaging applications, this technique
also has a great potential for non-destructive material characterisation and testing. Polarisation-sensitive (PS) OCT is a
recent extension of classical OCT that measures and images birefringence properties of a sample, which, however, has not yet
been applied to materials science. We present imaging of glass-fibre-enforced epoxy resin compounds and the detection of dry
spots, where the epoxy did not properly penetrate the glass-fibre structure. Furthermore, we demonstrate PS-OCT imaging of
the birefringence properties of different materials. The mapping of strain fields of samples under uniaxial and non-uniform
external stress and the detection of flow patterns in injection-moulded plastic parts could be demonstrated with this technique
for the first time.
Received: 21 October 2002 / Accepted: 22 November 2002 / Published online: 29 January 2003
RID="*"
ID="*"Corresponding author. Fax: +43-732/9015-5618, E-mail: david.stifter@uar.at 相似文献
8.
R. Frömter H.P. Oepen J. Kirschner 《Applied Physics A: Materials Science & Processing》2003,76(6):869-871
The basics of the scanning electron microscope with polarization analysis are briefly reviewed, emphasizing the achievable
magnetic resolution and image contrast. The design of an optimized spin-polarization detector based on the well-established
LEED scattering principle is presented. Results of first tests are reported.
Received: 2 September 2002 / Accepted: 2 September 2002 / Published online: 5 March 2003
RID="*"
ID="*"Corresponding author. Fax: +49-40/42838-6368, E-mail: RFroemte@PHYSnet.Uni-Hamburg.de 相似文献
9.
E. Gehrig O. Hess C. Seibert D. Woll R. Wallenstein 《Applied physics. B, Lasers and optics》2003,76(3):285-288
We theoretically describe and experimentally investigate the spatio-spectral wave mixing of induced and spontaneous emission
in large-area InGaAs-semiconductor laser amplifiers. The dynamic light-matter-coupling is described by a spatially resolved
theory based on Maxwell–Bloch–Langevin equations, taking into account many-body-carrier interactions, energy transfer between
the carrier and phonon systems and, in particular, the spatio-temporal interplay of stimulated and amplified spontaneous emission
and the noise caused by spontaneous emission. Our numerical model reveals the fundamental physical processes which are responsible
for the spectral power distribution of the amplified laser light and predicts the emission properties of high-power semiconductor
laser amplifiers, such as emission spectra and input power–output power characteristics.
Received:30October2002/Revisedversion:21November2002 / Published online: 12 February 2003
RID="*"
ID="*"Corresponding author. Fax: +49-711/6862-349, E-mail: Edeltraud.Gehrig@dlr.de
RID="**"
ID="**"Also at: Institute of Physics, Tampere University of Technology, P.O. Box 692, FIN-33101, Tampere, Finland
RID="***"
ID="***"Present address: Heidelberger Druckmaschinen AG, Speyerer Strasse 6, 69115 Heidelberg, Germany
RID="****"
ID="****"Present address: Lightbit Corporation, 411 Clyde Avenue, Mountain View, CA 94043, USA 相似文献
10.
B. Pura J. Petykiewicz M. Wierzbicki R. Cio lek Z. Wrzesiński 《Applied physics. B, Lasers and optics》2002,75(4-5):549-551
By ellipsometric measurements we have observed the polarization variations of the primary light beam, with wavelength λ1=5145 ?, interacting with the secondary light beam of controlled variable polarization, transmitted through a TGS crystal
layer. We present a theoretical explanation based on the second-order optical nonlinearity of TGS.
Received: 4 December 2001 / Revised version: 28 May 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +48-22/660-5447, E-mail: petyk@if.pw.edu.pl 相似文献
11.
N. Bärsch K. Körber A. Ostendorf K.H. Tönshoff 《Applied Physics A: Materials Science & Processing》2003,77(2):237-242
Although lasers are generally able to machine silicon, the major material in many microsystems applications, doing so without
influencing the physical properties of the bulk material remains an important challenge. Ultrafast lasers, in particular,
with their potential to precisely ablate all kinds of solid materials, are able to perform such processes with high efficiency
and accuracy. This article starts with an overview of the general interaction of ultrafast laser radiation with semiconductors,
explaining the absorption processes and different fluence regimes for the ablation of silicon. Major parameter influences,
especially for cutting processes in thin silicon, are described. By varying pulse energies, beam shaping methods, the beam
polarization, and temperatures, the cutting quality and speed can be significantly influenced. One important quality aspect,
besides kerf widths and surface roughness, is the amount of back-side chipping when cutting brittle materials. Achievements
in speed enhancement using linear focus shapes are presented, with cutting speeds up to five times higher than by conventional
spot-focusing. On the other hand, laser processes that cut with a spot focus offer the possibility of free-shape cutting,
which is explained using the example of wafers carrying silicon chips with highly increased package densities.
Received: 10 December 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +49-511/2788-100, E-mail: nb@lzh.de 相似文献
12.
Calculation of the temperature and thermal expansion of a STM tip heated by a short laser pulse 总被引:1,自引:0,他引:1
A mathematical model for the calculation of the temperature field in a scanning tunneling microscope (STM) tip under laser
illumination is developed. The duration of the laser pulse is a few nanoseconds or shorter. A Gaussian distribution of the
laser light intensity in time and space is assumed. Two different mechanisms of tip heating are taken into account: 1. due
to an enhanced electric field on the tip; 2. due to heating of the side surface of the tip by the focused spot of laser light.
An average tip temperature is calculated using the heat conductivity equation. The enhanced electric field on the tip is calculated
by the method of boundary integral equations.
Received: 20 August 2002 / Revised version: 4 December 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +49-2551/962-490, E-mail: sklein@fh-muenster.de 相似文献
13.
Z.W. Chen S.Y. Zhang S. Tan J.G. Hou Z.Q. Wu 《Applied Physics A: Materials Science & Processing》2003,76(1):33-35
In this paper, we report on the simulation of fractal clusters and the comparison with experimental fractal patterns. We found
that multiple fractal clusters can be formed in Au/Ge bilayer films for different annealing times. The fractal crystallization
area increases with the increase in the annealing time. The random successive nucleation model can simulate the actual growth
processes of multiple growth sites. The simulating fractal clusters are in good agreement with our experimental fractal patterns.
Received: 21 June 2001 / Accepted: 15 December 2001 / Published online: 3 June 2002
RID="*"
ID="*"Corresponding author. Fax: +86-551/3602-803, E-mail: chenzw@ustc.edu.cn 相似文献
14.
Mode splitting was observed when a He-Ne laser beam was reflected through a prism-coupled liquid-crystal slab waveguide under
an applied electric field. The splitting manifests itself as the imposed voltage reaches a critical level, and diminishes
when the voltage increases above a critical high value. If the applied voltage increases even further, mode splitting vanishes,
attributing to the result that almost all the directors of the liquid crystal turn upright to the surface. The multi-layer
matrix simulation can satisfactorily account for this phenomenon by exploiting the property of the anisotropic optical birefringence
of a liquid crystal under applied voltages.
Received: 2 December 2002 / Revised version: 24 January 2003 / Published online: 23 May 2003
RID="*"
ID="*"Corresponding author. Fax: +886/3572-3052, E-mail: jtlue@phys.nthu.edu.tw 相似文献
15.
H.R. Zeng G.R. Li Q.R. Yin Z.K. Xu 《Applied Physics A: Materials Science & Processing》2003,76(3):401-404
Pb(Zr,Ti)O3 (PZT) ferroelectric thin film was prepared by the sol-gel technique and crystallized with a (111) preferred orientation.
The domain structure and polarization reversal behavior were investigated by using scanning force microscopy (SFM) piezoresponse
mode at the nanometer scale. A step structure of approximately 30 nm in width was directly observed, which was formed during
the polarization reversal process. The presence of the step structure reveals that the forward domain-growth mechanism is
the dominant domain-switching process in our PZT thin films.
Received: 6 August 2002 / Accepted: 9 August 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +86-21/5241-3122, E-mail: huarongzeng@163.net 相似文献
16.
The temporal influence of a laser pulse on saturated laser-induced fluorescence is investigated by means of numerical solutions
of rate equations describing dynamical models of two- and four-level molecular systems. It turns out that temporal wings of
the laser become negligible if the saturated fluorescence power from the entire pulse is monitored instead of the total energy
obtained from the integrated fluorescence. The negligibility is evaluated relative to the saturation status obtained with
temporal sampling of the fluorescence signal as is commonly adopted in the time-resolved technique. The advantages and the
limitations of power measurements are discussed with reference to the experimental feasibility of pulse acquisitions for the
determination of the flawless saturation degree.
Received: 4 December 2002 / Revised version: 14 February 2003 / Published online: 5 May 2003
RID="*"
ID="*"Corresponding author. Fax: +39-06/3048-4811, E-mail: michele.marrocco@casaccia.enea.it 相似文献
17.
R. Kassing I.W. Rangelow E. Oesterschulze M. Stuke 《Applied Physics A: Materials Science & Processing》2003,76(6):907-911
Scanning probe microscopy is still suffering from reproducible fabrication of the corresponding sensors for mechanical, electrical,
optical, thermal and chemical material characterisation with highest lateral and/or time resolution. For batch-fabrication
techniques lithographic, dry etching and material problems have to be solved. Using such techniques, several types of cantilevers
and tips including piezoresistive detection systems have been demonstrated world-wide for the first time. Only an overview
is given here.
Received: 2 September 2002 / Accepted: 6 November 2002 / Published online: 5 March 2003
RID="*"
ID="*"Corresponding author. Fax: +49-561/804-4136, E-mail: kassing@physik.uni-kassel.de 相似文献
18.
N. Yasumaru K. Miyazaki J. Kiuchi 《Applied Physics A: Materials Science & Processing》2003,76(6):983-985
We report observation of nanostructures formed on thin TiN and DLC films that were irradiated by 800- and 267-nm, femtosecond
(fs) Ti:sapphire laser pulses at an energy fluence slightly above the ablation threshold. On the ablated thin-film surfaces,
the linearly polarized fs pulses produce arrays of fine periodic structures that are almost oriented to the direction perpendicular
to the laser polarization, while the circularly polarized light forms fine-dot structures. The size of these surface structures
is 1/10–1/5 of the laser wavelength and decreases with a decrease in the laser wavelength.
Received: 3 September 2002 / Accepted: 4 September 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +81-778/62-3306, E-mail: yasuma@fukui-nct.ac.jp 相似文献
19.
We find a way to record and retrieve images in a photorefractive LiNbO3 crystal using a single white light source instead of a coherent light source. According to the experimental results, we think this recording is not due to the recording of fanning gratings, but a variation of refractive index responding to the non-uniform illumination. We have also simulated the recording using the band transport model taking into account the photovoltaic effect. The simulation result agrees with the experimental results. 相似文献
20.
Laser action was generated in dye-doped sol–gel glass waveguides and in liquid solutions by crossing two beams from a frequency-doubled
neodymium:YAG laser. The angle between the polarization directions of the two beams was varied continuously from 90. The case
of 0° corresponded to pure intensity modulation. As the angle increased, the degree of intensity modulation decreased, resulting
in the decline and finally the demise of the laser output. At 90°, corresponding to pure polarization modulation, distributed
feedback laser action with narrow line-width output was again observed when the pump energy was increased three-fold. The
laser output also showed different polarization characteristics when the feedback mechanism was changed from intensity modulation
to polarization modulation.
Received: 13 February 2003 / Revised version: 3 April 2003 / Published online: 22 May 2003
RID="*"
ID="*"Corresponding author. Fax: 852/2603-5204, E-mail: dlo@sun1.phy.cuhk.edu.hk 相似文献