共查询到20条相似文献,搜索用时 129 毫秒
1.
N.V. Didenko E.M. Kim D.A. Muzychenko A.A. Nikulin O.A. Aktsipetrov 《Applied physics. B, Lasers and optics》2002,74(7-8):647-651
Incoherent second-harmonic generation, or hyper-Rayleigh scattering (HRS), and atomic force microscopy (AFM) are proposed
as a combined probe of nonlinear optical and structural properties of silver-island films. HRS and linear (Rayleigh) scattering
indicatrices are measured. The correlation function, deduced from the HRS indicatrices and characterising spatial fluctuations
of the total polarisation at second-harmonic frequency, has a length scale significantly larger than that of the correlation
functions that are obtained from the AFM data and characterise spatial fluctuations of quadratic optical susceptibilities
of the dipole and quadrupole types. This difference is interpreted as indicating that the HRS indicatrix shape is determined
by the long-range fluctuations of the local-field factors.
Received: 16 October 2001 / Revised version: 16 April 2002 / Published online: 6 June 2002 相似文献
2.
We show analytically that in phase-mismatched second-harmonic generation, an effective diffraction is induced at the second-harmonic (SH) frequency. Numerical simulation results agree with the analytical predictions. Compared to the case of linear propagation, the effect of the overall diffraction at the SH frequency becomes doubled due to the induced diffraction, which causes an interesting result that the SH beam width will be larger than that of the fundamental field. 相似文献
3.
E. Api naniz F. Plazaola J.S. Garitaonandia 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(2):167-177
Tight Binding Linear Muffin-Tin Orbital (TB-LMTO) electronic calculations are presented for the magnetic and structural properties
of ordered and disordered FeAl alloys. The total energy, bulk modulus, lattice parameter and magnetic moments of B2, D03 and
B32 ordered structures and A2 disordered structure were calculated for different compositions. The different structures are
obtained by varying the position of Fe and Al atoms in a BCC superstructure. In this way, we examine the order-disorder transition
that takes place in these alloys. Disordered alloys present both larger Fe magnetic moment and lattice parameter than ordered
ones. In this work comparison of the calculated quantities with available experimental results is provided and it can be concluded
that the results are in quantitative agreement with the experimental trends.
Received 7 May 2002 / Received in final form 20 September 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: eaf@we.lc.ehu.es 相似文献
4.
A. Melnikov O. Krupin U. Bovensiepen K. Starke M. Wolf E. Matthias 《Applied physics. B, Lasers and optics》2002,74(7-8):723-727
The magnetization of 10-nm Gd films on W (110) has been investigated with second-harmonic generation (SHG). We observed a
strong second-harmonic (SH) yield, which we attribute to resonance enhancement by the well-known Gd (0001) d-like surface
state above the Fermi level. Since this state is spin-polarized it enhances the magnetic SHG contrast. The contrast, the relative
phase between odd and even SH fields, and the amplitude ratio of these fields depend strongly on wavelength, which confirms
the resonance enhancement. Further proof is provided by the fact that oxidation of the Gd surface reduces the SH yield by
an order of magnitude.
Received: 16 October 2001 / Revised version: 21 March 2002 / Published online: 11 June 2002 相似文献
5.
S. Milita Y. Le Tiec E. Pernot L. Di Cioccio J. Härtwig J. Baruchel M. Servidori F. Letertre 《Applied Physics A: Materials Science & Processing》2002,75(5):621-627
A new process was recently developed to manufacture silicon carbide on insulator structures (SiCOI). The process consists
of several steps: (i) hydrogen implantation into an oxidised SiC wafer, (ii) bonding the oxidised surface of this wafer to
an oxidised silicon substrate and (iii) high temperature splitting of a thin SiC film from the SiC wafer at the depth of the
maximum hydrogen concentration and further annealing of the splitted film. The defect generation occurring during this process
was investigated by synchrotron radiation X-ray diffraction topography, with special emphasis on to the last two steps. Various
X-ray topographic techniques were used to characterise the lattice defects inside the SiC wafer, to quantify the strong lattice
distortion near the edges of the splitted SiC film and to reveal SiC film regions lost during the splitting process. Moreover,
we show that the strain fields of dislocations, observed in the silicon substrate after high temperature splitting and annealing
of the splitted structure, induce a corresponding deformation in the thin SiC overlayer, despite the presence of the sandwiched
oxide film. The defect density is much lower in the central region of the SiCOI structure.
Received: 29 June 2001 / Accepted: 8 November 2001 / Published online: 20 March 2002 相似文献
6.
T.V. Dolgova D. Schuhmacher G. Marowsky A.A. Fedyanin O.A. Aktsipetrov 《Applied physics. B, Lasers and optics》2002,74(7-8):653-659
The technique of combined optical second-harmonic (SH) intensity and phase spectroscopy, which is the spectroscopic modification
of SH phase measurements, is proposed to study the nonlinear optical response of semiconductor interfaces with spectrally
close resonant contributions. The spectral dependences of SH intensity and phase from oxidised Si (111) and Ge (111) surfaces
are studied in the range of 3.5- to 5-eV SH photon energy. The resonant behaviour of combined SH spectra is associated with
a superposition of contributions from direct interband transitions at several critical points of Si and Ge band structures.
Received: 16 October 2001 / Revised version: 16 April 2002 / Published online: 6 June 2002 相似文献
7.
R.K. Drampyan 《Applied physics. B, Lasers and optics》2002,75(4-5):557-561
A laser-induced electric microfield in potassium vapor partially ionized by laser radiation and placed in an external magnetic
field has been studied experimentally. It was found that the dependence of the electric field rise time on the magnetic field
strength had a peak value when the plasma frequency is equal to the Larmor frequency. This finding allows us to measure the
photoelectron density in weakly ionized potassium vapor. The results are explained in terms of a simple model that shows how
the length of the photoelectron trajectory changes with the magnetic field.
Received: 4 February 2002 / Revised version: 20 June 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +374-32/31172, E-mail: rdramp@ipr.sci.am 相似文献
8.
M. Fiebig 《Applied physics. B, Lasers and optics》2002,74(7-8):749-758
Magnetic second-harmonic generation (SHG) and three-photon difference-frequency generation (DFG) are used to investigate the
magnetic phase diagrams of MnO3
3- compounds with five- and sixfold coordination of the Mn3+ (3d4) ion. In the hexagonal manganites, the six basic antiferromagnetic structures following from a one-dimensional representational
analysis of the hexagonal unit cell are clearly distinguished on the basis of their different selection rules for SHG. All
structures break the geometric frustration of the unit cell by triangular antiferromagnetic ordering of the Mn spins. The
stability and the mutual interactions of in-plane and inter-plane exchange and the in-plane anisotropy are investigated. The
three quantities act as almost decoupled degrees of freedom, which leads to independent in-plane and inter-plane reorientations
of the Mn spin lattice. DFG was observed in the orthorhombic manganites Pr1-xCaxMnO3 and Nd1-xSrxMnO3. The DFG reflects the fourfold anisotropy of the quasicubic crystal, and the independent tensor elements for DFG are determined
quantitatively. A metal–insulator transition with a two-order-parameter coupling to antiferromagnetism and charge ordering
leads to additional difference-frequency contributions, which allow us to observe the formation of ∼100 μm magnetic domains.
The variety of results gained from the two vastly different groups of manganite compounds, with spectral and spatial resolution
used as additional degrees of freedom, demonstrates the versatility of nonlinear magnetooptical experiments for the investigation
of magnetic structures and symmetries.
Received: 16 October 2001 / Published online: 2 May 2002 相似文献
9.
First- and second-harmonic radiations in frequency regions centered around 120 and 240 GHz, respectively, have been observed from a gyromonotron employing magnetic fields between 34 and 54 kG and a magnetron injection gun preducing a 30-kV, 1- to 2-A electron beam. Extensive redesign of the cavity, electron beam tunnel holders, and vacuum envelope resulted in greatly improved tube performance over that obtained previously. Nine first-harmonic modes and three second-harmonic modes were identified with specific TE cavity modes. These identifications were based on agreement between the measured frequency of a radiation and the calculated resonant frequency of a TE mode, and one or both of the following: (a) the agreement between the magnetic field at which the radiation occurred and that predicted by linear theory calculations of threshold current versus magnetic field for that mode; and (b) the similarity between the far-field antenna pattern measured with calibrated, waveguide-mounted detectors and that predicted for that mode. Output power was measured with a Scientech 362 Calorimeter and also estimated by integrating the far-field antenna patterns measured with the calibrated detectors. The power ranged from a fraction of a watt to 200 W for second-harmonic modes, and from tens of watts to 2 kW for first-harmonic modes. 相似文献
10.
We study the quark mass expansion of the magnetic moments of the nucleon in a chiral effective field theory including nucleons,
pions and delta-resonances as explicit degrees of freedom. We point out that the usual power counting applied so far to this
problem misses important quark mass structures generated via an intermediate isovector M1 nucleon-delta transition. We propose a modified power counting and compare the resulting chiral extrapolation function to
available (quenched) lattice data. The extrapolation is found to work surprisingly well, given that the lattice data result
from rather large quark masses. Our calculation raises the hope that extrapolations of lattice data utilizing chiral effective
field theory might be applicable over a wider range in quark masses than previously thought, and we discuss some open questions
in this context. Furthermore, we observe that within the current lattice data uncertainties the extrapolations presented here
are consistent with the Padé fit ansatz introduced by the Adelaide group a few years ago.
Received: 23 April 2002 / Accepted: 18 July 2002 / Published online: 17 December 2002
RID="c"
ID="c"e-mail: themmert@physik.tu-muenchen.de
RID="d"
ID="d"e-mail: weise@ect.it
Communicated by A. Sch?fer 相似文献
11.
D.M. Newman M.L. Wears R.J. Matelon D. McHugh 《Applied physics. B, Lasers and optics》2002,74(7-8):719-722
The behaviour of the reflectivity and Kerr magneto-optic effects in the non-linear second-harmonic (SH) field diffracted from
nano-scale structured ferromagnetic interfaces is reported. Measurements are made in both the linear and non-linear fields
at two different fundamental wavelengths (1064 nm and 800 nm) and their associated harmonics. Resonant behaviour observed
as a function of angle of incidence is identified with surface-plasmon production that is known to intensify the local field
within the interface. Radiation incident at angles of incidence that optimise coupling to the electron plasma produces an
increase in the SH field radiated in the vicinity of those angles. Similarly, at those angles of incidence where radiation
at the SH wavelengths (532 nm and 400 nm) couples optimally to the electron plasma, troughs are seen in the angular spectrum
of the generated SH radiation. Kerr magneto-optic measurements taken in both the linear field and the SH field both show very
significant enhancement at angles meeting the plasma-resonance condition. The totality of experimental data presented allows
the conclusion that intensification of the interface electric field due to plasmon creation enhances not only the SH reflection
coefficient, as was already known, but also the magneto-optic reflection coefficients in both linear and SH fields.
Received: 16 October 2001 / Revised version: 14 March 2002 / Published online: 29 May 2002 相似文献
12.
Based on a parameterized electronic many-body theory we calculate the spectrum of optical second-harmonic generation (SHG)
on an antiferromagnetic (AF) surface: NiO (001). The occurrence of AF spectral lines is further exploited for the calculation
of ultra-fast spin dynamics. This spin dynamics is observable in SHG. It is characterized by both a sharp drop of the AF signal
within a few femtoseconds and a long persistence (up to nanoseconds) of the spin coherence. These two features constitute
an ideal system for possible applications in both magnetic recording and quantum computing.
Received: 16 October 2001 / Revised version: 21 March 2002 / Published online: 6 June 2002 相似文献
13.
M. Gorkunov M. Lapine E. Shamonina K.H. Ringhofer 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(3):263-269
Effective magnetic properties of a composite meta-material consisting of periodically arranged circular conductive elements
are studied theoretically. A general expression for the effective bulk permeability is obtained with mutual effects and lattice
ordering being taken into account. The resonance frequency of the permeability is found to be strongly dependent on the size
and shape of the unit cell. Frequency dispersion of the permeability is studied with special attention paid to the frequency
range, where negative values of the permeability are possible. Corresponding recommendations for optimisation of the meta-materials
with negative permeability are made. The results are confirmed by numerical simulations of the finite structure behaviour
in an external magnetic field.
Received 19 April 2002 Published online 31 July 2002 相似文献
14.
A generalised formalism of characteristic matrices is presented to analyse second-harmonic magneto-optical Kerr effects in
an optically anisotropic centrosymmetric ferromagnetically ordered multilayer if its response can be described in terms of
electric polarisation. Features of the model associated with ideal (infinitely thin) interfaces are highlighted. These are
due to both the existence of two versions of unconventional boundary conditions and an inevitable conventional approach to
defining the surface polarisations through the fundamental electric field and surface-susceptibility tensors. New analytical
results for linear and second-harmonic Kerr effects are shown to be advantageous for developing an effective algorithm for
their numerical simulation. The linear approximation with respect to magnetisation is pursued, thereby also making our results
suitable for investigating a great variety of magneto-optical effects and (in the second-harmonic case) effects related to
anisotropy.
Received: 16 October 2001 / Published online: 24 April 2002 相似文献
15.
V. Venkataramanan K. Noguchi M. Aono T. Suzuki 《Applied physics. B, Lasers and optics》2002,74(7-8):683-689
We describe the instrumentation related to the first observation of magnetization-induced enhancement of surface second-harmonic
generation (SHG) from the paramagnetic Si(111)-7×7 surfaces. A judicious choice of polarization and sample orientation enabled
us to isolate the magnetic-field-dependent tensor element of the nonlinear susceptibility. A conductive liquid-nitrogen system,
coupled to an ultrahigh-vacuum system that is immune to the high magnetic field of 10 T, cooled the sample to about 120 K.
A high extinction that is necessary to detect the magnetization-induced SHG (MSHG) was accomplished by minimizing stray optical
effects such as Faraday rotation, photoluminescence and thermal birefringence in all optical components, with extra care taken
for the UHV window. Consistent and stable operation of this sensitive measurement system permitted experiments involving MSHG
at multiple wavelengths and temperatures. Probing the magnetization-induced optical nonlinearity was validated by quenching
the surface states by oxidation of the surface layers. From MSHG measurements at two wavelengths resonant with different surface-state
transitions, we were able to suggest that the observed MSHG is proportional to the number of dangling bond states of Si(111)-7×7.
Received: 15 January 2002 / Published online: 2 May 2002 相似文献
16.
T.V. Dolgova V.G. Avramenko A.A. Nikulin G. Marowsky A.F. Pudonin A.A. Fedyanin O.A. Aktsipetrov 《Applied physics. B, Lasers and optics》2002,74(7-8):671-675
Size effects in the resonant nonlinear optical response of amorphous Si/SiO2 multiple quantum wells (MQW) are studied by second-harmonic generation (SHG) spectroscopy in a spectral interval of second-harmonic
photon energies from 2.5 to 3.4 eV. The sensitivity of SHG spectroscopy to thickness-dependent electronic structure (sub-band
energy position and density of states line shape) of MQW is demonstrated. A monotonic red shift of central energies of SHG
resonances by 120 m eV upon increase of the well thickness from 2.5 to 10 ? is observed. This is interpreted as a size dependence
of the position of singularities in the combined density of states for a 2D gas of electrons moving in an effective potential
well. It is shown that, for agreement with experiment, the simplest (rectangular) shape of the well should be modified in
order to take into account the lattice-potential distortion at the interfaces.
Received: 16 October 2001 / Revised version: 16 April 2002 / Published online: 6 June 2002 相似文献
17.
Interference patterns generated by a regular lattice of SiO2 microspheres on a transparent support are used for the surface patterning of polyimide (PI) foils. Using 248 nm excimer-laser
radiation, thousands to millions of holes with a full width at half maximum (FWHM) of 160±40 nm can be generated with a single
laser pulse.
Received: 1 March 2002 / Accepted: 4 March 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +43-732/2468-9242, E-mail: dieter.baeuerle@jku.at 相似文献
18.
Ch. Schwedes E. Peik J. von Zanthier A.Y. Nevsky H. Walther 《Applied physics. B, Lasers and optics》2003,76(2):143-147
A compact, tunable and narrow-bandwidth laser source for blue and ultraviolet radiation is presented. A grating-stabilized
diode laser at 922 nm is frequency-stabilized to below 100 Hz relative to a reference resonator. Injection of the diode-laser
light into a tapered amplifier yields a power of 0.5 W. In a first frequency-doubling stage, more than 200 mW of blue light
at 461 nm is generated by use of a periodically poled KTP crystal. Subsequent second-harmonic generation employing a BBO crystal
leads to about 1 mW of ultraviolet light at 231 nm.
Received: 12 August 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +49-89/32905-200, E-mail: christian.schwedes@mpq.mpg.de
RID="**"
ID="**"Present address: PTB, Bundesallee 100, 38116 Braunschweig, Germany 相似文献
19.
Guanghui Zhang Dong Xu Mengkai Lü Duorong Yuan Xingqiang Wang Fanqing Meng Shiyi Guo Quan Ren Minhua Jiang 《Optics & Laser Technology》2001,33(2)
Violet 404-nm radiation is generated by type-I single-pass frequency doubling of the output of an GaAlAs diode laser in critically phase-matched ZnCd(SCN)4 (ZCTC) crystal, a metallo-organic complex crystal. In this paper, its refractive index and second-harmonic generation phase-matching angles are reported. Using a 3-mm-long ZCTC crystal, a diode laser power of 473 mW generated 390 μW of second-harmonic radiation. More recently, 380-nm, 20 μW ultraviolet (UV) radiation is also realized by frequency doubling of the 100 mW output of a continuous-wave Ti:sapphire laser at 760 nm. ZCTC is a promising UV nonlinear optical candidate material for frequency doubling of diode lasers. 相似文献
20.
We have observed saturation of the intensity of magnetically induced second-harmonic radiation in atomic sodium vapor and rotation of the polarization angle of the second-harmonic radiation from that of the fundamental field at the magnetic field of about 1 kG. These phenomena have been fully analyzed, and explained by the Hanle effect of the second-harmonic quadrupole moments observed in the forward direction. A possibility of measuring the transverse relaxation times of the E2 allowed transition is suggested. 相似文献