共查询到20条相似文献,搜索用时 31 毫秒
1.
T. Lottermoser M. Fiebig D. Fröhlich S. Kallenbach M. Maat 《Applied physics. B, Lasers and optics》2002,74(7-8):759-764
Second-harmonic generation (SHG) is used as a probe for the coexisting ferroelectric and antiferromagnetic orders in hexagonal
RMnO3. SH contributions coupling to the electric and/or magnetic order parameters are identified on the basis of their spectral
dependence and the symmetries of the corresponding order parameters. The SH signals from the ferroelectric and antiferromagnetic
orders were employed to image the electric and magnetic domain structures separately. The transformation properties of electric
and magnetic domains are discussed with respect to the transformation properties of the corresponding order parameters. An
investigation of the mutual coupling between the coexisting electric and magnetic orders reveals apparently independent domain
structures, which contradicts the symmetry and transformation properties of electric-dipole-induced SHG in this ferroelectromagnetic
group of compounds. Apart from higher-order multipole contributions to SHG, interface contributions from clamped electric
and magnetic domains can solve the contradiction.
Received: 16 October 2001 / Published online: 24 April 2002 相似文献
2.
Nonlinear optical and electrostatic force microscopy for ferroelectric polarization imaging 总被引:1,自引:0,他引:1
E.D. Mishina N.E. Sherstyuk K.A. Vorotilov A.S. Sigov R. Barberi M.P. Moret F. Manders M.P. De Santo P.K. Larsen T. Rasing 《Applied physics. B, Lasers and optics》2002,74(7-8):783-788
Second-harmonic generation (SHG)-based nonlinear optical microscopy is used for spatially resolved imaging of the polarization
switching in lead zirconium titanate ferroelectric thin films. The local SHG hysteresis loops reveal a strong dependence on
film composition and structure. The SHG microscopy results are in good agreement with the efficiency of electrostatic force
microscopy writing and allow us to predict the microscopic dielectric memory efficiency, both in contact and contact-less
ways.
Received: 15 January 2001 / Revised version: 27 March 2002 / Published online: 6 June 2002 相似文献
3.
E.D. Mishina A.I. Morosov Q.-K. Yu S. Nakabayashi T. Rasing 《Applied physics. B, Lasers and optics》2002,74(7-8):765-775
A general approach of second-harmonic generation (SHG) studies for surface phase transitions (PTs) is presented, with a thermodynamic
classification of surface PTs and their relation to SHG parameters. The symmetry aspects of SHG near a surface PT are discussed,
including issues connected with separation of surface and bulk contributions and the role of atomic and mesoscopic inhomogeneities.
This approach is illustrated by applying it to two systems revealing a (near-) surface PT: single-crystalline SrTiO3 near a bulk structural PT and single-crystalline Au in an electrochemical cell revealing an order–disorder and a reconstructive
PT.
Received: 15 January 2002 / Published online: 11 June 2002 相似文献
4.
In this paper the second harmonic generation (SHG) in generalized Thue-Morse (GTM(m, n)) ferroelectric superlattices is studied. Under the small-signal approximation, the SHG spectra in both real and reciprocal spaces are investigated. It is found that: (1) only when the structure parameters l, lA, and lB are all chosen to be proper, can SHG in GTM(m, n) ferroelectric superlattices be generated; (2) for Family A of generalized Thue-Morse, GTM(m, 1) ferroelectric systems, with the increase of parameter m, the intense peaks of SHG concentrate on the long wavelength (the fundamental beam (FB) wavelength is within ), but for Family B of generalized Thue-Morse, GTM(1, n) ferroelectric superlattices, with the increase of parameter n, the intense peaks of SHG concentrate on the middle wavelength ; and (3) for GTM(m, 1) ferroelectric superlattices, the bigger the m, the stronger the relative integral intensity (RII) of SHG would be, but for GTM(1, n) ferroelectric systems, the bigger the n, the weaker the RII of SHG would be. 相似文献
5.
C. Du Z. Wang J. Liu X. Xu B. Teng K. Fu J. Wang Y. Liu Z. Shao 《Applied physics. B, Lasers and optics》2001,73(3):215-217
We report, for the first time, efficient intracavity second-harmonic generation (SHG) at 1.06 μm in a non-linear optical crystal,
BiB3O6 (BIBO), at a type-I phase-matching direction of (θ,ϕ)=(168.9°,90°), performed with a LD end-pumped cw Nd:YVO4 laser. A cw SHG output power of 364 mW has been obtained using a 1.9-mm-thick BIBO crystal. The optical conversion efficiency
was 12.2% and the corresponding effective intracavity SHG efficiency was determined to be 32.4%. It was found that the intracavity
SHG efficiency is greater than that obtained with a type-II phase-matching KTiOPO4 (KTP) crystal with a thickness of 3 mm. The effective non-linear optical coefficient (deff) ratio of BIBO to that of KTP, determined experimentally, is 1.23:1.
Received: 7 May 2001 / Revised version: 6 July 2001 / Published online: 19 September 2001 相似文献
6.
J. Liu X. Xu C.Q. Wang S. Zhang J. Wang H. Chen Z. Shao M. Jiang 《Applied physics. B, Lasers and optics》2001,72(2):163-166
The characteristics of intracavity second-harmonic generation (SHG) at 1.06 μm in GdCa4O(BO3)3 (GdCOB) crystals cut for different type I phase-matching (PM) directions of (θ,φ)=(66.8°, 132.3°); (19.4°, 0°); (90°, 46°)
have been investigated. It was found that the intracavity SHG was significantly efficient in the PM direction of (66.8°, 132.3°),
and that the intrinsic lower effective nonlinear coefficient (deff) was responsible for the less-efficient SHG in the other two directions. A maximum CW SHG output power of 2.81 W was obtained
with an optical conversion efficiency of 18.7%, while the corresponding effective intracavity SHG efficiency was determined
to be 41.3%. The intracavity SHG efficiency of GdCOB has been found to reach two-thirds of that obtained with type II phase-matching
KTiOPO4 (KTP).
Received: 26 April 2000 / Revised version: 3 July 2000 / Published online: 5 October 2000 相似文献
7.
X.H. Liu Z.G. Liu Y.P. Wang T. Zhu J.M. Liu 《Applied Physics A: Materials Science & Processing》2003,76(2):197-199
Mainly [115]-oriented SrBi2Ta2O9 (SBT) films were prepared on GaAs(100) substrates with TiO2 buffer layers. Both the SBT films and the TiO2 buffer layers were deposited by pulsed laser deposition (PLD) using a KrF excimer laser. The depth profile of the constituent
elements observed by Auger electron spectrometry (AES) shows no remarkable diffusion at both the interfaces between SBT and
TiO2 and between TiO2 and the GaAs substrate. The electrical characteristics of the Pt/SBT/TiO2/GaAs(100) structures show a ferroelectric hysteresis loop with a small remanent polarization (∼0.5 μC/cm2).
Received: 1 March 2002 / Accepted: 3 March 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/3595535, E-mail: xhliu81@hotmail.com
RID="**"
ID="**"Present address: Data Storage Institute, DSI Building, 5, Engineering Drive 1 (off Kent Ridge Crescent, NUS) 117608
Singapore 相似文献
8.
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
9.
M. Danckwerts E. Savinova B. Pettinger K. Doblhofer 《Applied physics. B, Lasers and optics》2002,74(7-8):635-639
We combine in situ electrochemical second-harmonic generation (SHG) with voltammetry measurements using the hanging meniscus
configuration. This setup is used to investigate the interface between a Ag (111) electrode and an alkaline electrolyte. The
study offers a new in situ insight into the electrochemical processes at the Ag (111) electrode during OH adsorption and subsequent
oxidation. The behavior of SHG isotropic and anisotropic contributions as a function of potential is discussed and related
to the interfacial electric field. Comparison of the results with previous investigations of the Ag underpotential oxidation
in alkaline solutions shows that submonolayer oxidation is followed by bulk oxidation.
Received: 16 October 2001 / Revised version: 26 March 2002 / Published online: 6 June 2002 相似文献
10.
R. Dinu M. Dinescu J.D. Pedarnig R.A. Gunasekaran D. Bäuerle S. Bauer-Gogonea S. Bauer 《Applied Physics A: Materials Science & Processing》1999,69(1):55-61
Ferroelectric SrBi2Ta2O9 (SBT) films were grown by pulsed-laser deposition (PLD) at different substrate temperatures and fluences. A correlation between
film structure and ferroelectric properties is established. The dielectric function ε′ of thin SBT films shows a Curie–Weiss behavior well below the peak temperature Tmax and relaxor-like behavior in the vicinity of Tmax. Domain walls have a strong influence on the dielectric and ferroelectric properties and on the polarization fatigue of SBT
films below 100 °C. The formation of ferroelectric phases is favored at lower substrate temperatures by incorporating Bi2O3 template layers into the structure.
Received: 18 March 1999 / Accepted: 19 March 1999 / Published online: 5 May 1999 相似文献
11.
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
12.
G.S. Neugschwandtner R. Schwödiauer S. Bauer-Gogonea S. Bauer 《Applied Physics A: Materials Science & Processing》2000,70(1):1-4
Large piezoelectric d33 coefficients around 600 pC/N are found in corona-charged non-uniform electrets consisting of elastically “soft” (microporous
polytetrafluoroethylene PTFE) and “stiff” (perfluorinated cyclobutene PFCB) polymer layers. The piezoelectric activity of
the two-layer fluoropolymer stack exceeds the d33 coefficient of the ferroelectric ceramic lead zirconate titanate (PZT) by more than a factor of two and that of the ferroelectric
polymer polyvinylidene fluoride (PVDF) by a factor of 20. Soft piezoelectric materials may become interesting for a large
number of sensor and transducer applications, in areas such as security systems, medical diagnostics, and nondestructive testing.
Accepted: 9 November 1999 / Published online: 3 December 1999 相似文献
13.
G.N. Zhizhin E.V. Alieva L.A. Kuzik V.A. Yakovlev D.M. Shkrabo A.F.G. van der Meer M.J. van der Wiel 《Applied Physics A: Materials Science & Processing》1998,67(6):667-673
2 , BaF2, MgO, LiNbO3 were determined. The nonlinear spectroscopy applications of SEW–FEL techniques to studies of a second-harmonic generation
(SHG) on crystal surfaces in the regime of counterpropagating SEWs – the frequency dependence of efficiency and the influence
of a thin film deposition on a quartz surface – are described.
Received: 15 May 1998/Accepted: 25 August 1998 相似文献
14.
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
15.
Lagerwall JP Heppke G Giesselmann F 《The European physical journal. E, Soft matter》2005,18(1):113-121
We study the effects of mixing ferroelectric and antiferroelectric liquid-crystal compounds (FLCs and AFLCs) when the former
are strictly synclinic and the latter strictly anticlinic, i.e. one mixture component exhibits only SmC* and the other only SmC a* as tilted phase. Three different paths between syn- and anticlinicity were detected: transition directly between SmC* and
SmC a*, transition via the SmCβ* and SmCγ* subphases, or by “escaping” the clinicity frustration by reducing the tilt to zero, i.e. the SmA* phase is extended downwards in temperature, separating SmC* from SmC a* in the phase diagram. The most common path is the one via the subphases, demonstrating that these phases appear as a result
of frustration between syn- and anticlinic and, consequently, between syn- and antipolar order. For assessing the role of
chirality, we also replaced the FLC with non-chiral synclinics. With one of the AFLCs, the route via supbhases was detected
even in this case, suggesting that chirality --although necessary-- does not have quite the importance that has previously
been attributed to the appearance of the subphases. The path chosen in the mixture study seemed to be determined mainly by
the synclinic component, the subphase induction occurring only when the SmA*-SmC* transition was second order. 相似文献
16.
K. Pedersen T.B. Kristensen T.G. Pedersen P. Morgen Z. Li S.V. Hoffmann 《Applied physics. B, Lasers and optics》2002,74(7-8):677-682
Thin noble metal films (Ag, Au and Cu) on Si (111) have been investigated by optical second-harmonic generation (SHG) in combination
with synchrotron radiation photoemission spectroscopy. The valence band spectra of Ag films show a quantization of the sp-band
in the 4-eV energy range from the Fermi level down to the onset of the d-bands. For Cu and Au the corresponding energy range
is much narrower and quantization effects are less visible. Quantization effects in SHG are observed as oscillations in the
signal as a function of film thickness. The oscillations are strongest for Ag and less pronounced for Cu, in agreement with
valence band photoemission spectra. In the case of Au, a reacted layer floating on top of the Au film masks the observation
of quantum well levels by photoemission. However, SHG shows a well-developed quantization of levels in the Au film below the
reacted layer. For Ag films, the relation between film thickness and photon energy of the SHG resonances indicates different
types of resonances, some of which involve both quantum well and substrate states.
Received: 16 October 2001 / Revised version: 14 March 2002 / Published online: 29 May 2002 相似文献
17.
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
18.
Second-harmonic generation (SHG) results for Ni and Co films on Cu (001) have been reinvestigated regarding the depth sensitivity
of this technique for thin films. We find that tangential components of the nonlinear susceptibility are much more sensitive
to real film properties than normal components, which are confined to surfaces and interfaces. In consequence, for SHG experiments
on ultra-thin metal films, polarization combinations should be favored that possess only tangential susceptibility components,
even though the yield is weaker. Additional phase measurements are necessary to obtain full information about the film.
Received: 20 January 2002 / Published online: 6 June 2002 相似文献
19.
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
20.
L. Zhang W. Kleemann J. Dec R. Wang M. Itoh 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(2):163-171
The dielectric permittivity ε′ - i
of SrTi 18O 3 (STO18) is studied under a dc electric field E as a function of the temperature, T. In ε′
vs.
T, a double-peak is found when 0 < E < 30 KV/m. While the peak at high-T is attributed to the smeared ferroelectric phase transition, the low-T one is induced by domain wall motion. The transverse Ising model including an external homogeneous and quenched random-fields
is successfully used to describe both the smeared phase transition and the domain wall response in the low-T domain state. The calculations are in good agreement with the experimental results.
Received 4 January 2002 / Received in final form 25 March 2002 Published online 19 July 2002 相似文献