共查询到20条相似文献,搜索用时 31 毫秒
1.
Michael Esseling Annamaria Zaltron Nicola Argiolas Giovanni Nava Jörg Imbrock Ilaria Cristiani Cinzia Sada Cornelia Denz 《Applied physics. B, Lasers and optics》2013,113(2):191-197
We investigate the applicability of highly reduced lithium niobate samples doped with iron for the use as optoelectronic tweezers. Increasing the reduction degree of Fe-doped lithium niobate is well known to increase the photoconductivity and reduce the writing time of internal space-charge fields. Based on our measurements of the photorefractive properties, we determine the optimal conditions for dielectrophoretic trapping and present the application of Fe-doped lithium niobate as optoelectronic tweezers. For higher reduction degrees, an unexpected decrease in the photovoltaic current density and the saturation space-charge field is reported. 相似文献
2.
In lithium niobate crystals doped with photorefractive iron and copper admixtures when lightening objects with broadband incoherent radiation one can observe typical orientation and polarized dependences of image contrast. The record does not realize at orientation of light bands in the image parallel to the polar axis of the crystal. 相似文献
3.
The transformations of the transverse profiles of laser beams in a nonlinear Fabry-Perot interferometer based on lithium niobate
crystals with a surface layer doped with a combination of photorefractive impurities (iron and copper ions) have been experimentally
investigated. It is demonstrated that the distribution of transmitted beam intensity significantly changes for a few seconds
at milliwatt beam powers. 相似文献
4.
K. V. Shandarova V. M. Shandarov E. V. Smirnov D. Kip M. Stepić C. Rüter 《Russian Physics Journal》2006,49(9):964-969
Special features of linear and nonlinear propagation of coherent light beams in two-dimensional photorefractive photonic lattices
optically induced in the lithium niobate crystal doped with iron are experimentally investigated. The two-dimensional gratings
are formed by consecutive recording of two one-dimensional photorefractive gratings in the crystal. Experiments were performed
using He-Ne laser irradiation with a wavelength of 633 nm.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 58–62, September, 2006. 相似文献
5.
G. Mandula M. A. Ellabban R. A. Rupp M. Fally E. Hartmann L. Kovács 《辐射效应与固体损伤》2013,168(1-6):173-179
The activation energy of thermal fixing of photorefractive gratings is determined in congruent and nearly stoichiometric lithium niobate crystals, both doped with iron or manganese. The novel technique called holographic scattering method is compared with the standard two-wave mixing method. A measurement of the angular distribution of the self scattered intensity and its possible analytical function is presented. The mathematical problems of the holographic scattering method are discussed applying the angular distribution functions. 相似文献
6.
Synthesis and characterization of Ca2Sn1-xCexO4 with blue luminescence originating from Ce^4+ charge transfer transition 下载免费PDF全文
Ce^4+-doped Ca2SnO4 with a one-dimensional structure, which emits bright blue light, is prepared by using a solid-state reaction method. The x-ray diffraction results show that the Ce^4+ ions doped in Ca2SnO4 occupy the Sn^4+ sites. The excitation and emission spectra of Ca2Sn1-xCexO4 appear to have broad bands with peaks at - 268nm and -442nm, respectively. A long excited-state lifetime (-83μs) for the emission from Ca2Sn1-xCexO4 suggests that the luminescence originates from a ligand-to-metal Ce^4+ charge transfer (CT). The luminescent properties of Ca2Snl_xCexO4 have been compared with those of Sr2CeO4, which is the only material reported so far to show Ce^4+ CT luminescence. More interestingly, it is observed that the emission intensity of Ca2Sn1-xCexO4 with a small doping concentration (x - 0.03) is comparable to that of Sr2CeO4 in which the concentration of active centre is 100%. 相似文献
7.
Yu-Long Ma 《中国物理 B》2022,31(4):43401-043401
Debye-screening effects on the electron-impact excitation (EIE) processes for the dipole-allowed transition 1s$^{2}$ $^{1}{\rm S} \to 1$s2p $^{1}$P in He-like Al$^{11+}$ and Fe$^{24+}$ ions are investigated using the fully relativistic distorted-wave methods with the-Hückel (DH) model potential. Debye-screening effects on the continuum-bound (CB) interaction and target ion are discussed, both of which result in reduction of EIE cross sections. This reduction due to screening on the CB interaction is dominant. The non-spherical and spherical DH potentials are adopted for considering the screening effect on the CB interaction. It is found that the spherical DH potential could significantly overestimate the influence of plasma screening on EIE cross sections for multielectron He-like ions. 相似文献
8.
Thermo-electric method for nearly complete oxidization of highly iron-doped lithium niobate crystals
A new method is presented, allowing the nearly complete oxidization of lithium niobate crystals (LiNbO3), doped with large amounts of iron oxide (0.05–3 wt. % Fe2O3) utilizing annealing at 700 °C in the presence of externally applied electric fields. The treatment results in a concentration
ratio of Fe2+ and Fe3+ ions of less than 2×10-3. Strong oxidization of iron in LiNbO3 reduces the photorefractive effect and is therefore of particular interest for nonlinear-optical applications.
PACS 42.65.-k; 66.30.Hs; 71.55.-i 相似文献
9.
The time dependence of the photorefractive light scattering in lithium niobate single crystals of the congruent composition
(LiNbO3) doped by “photorefractive” Cu cations (0.015 wt %) is studied for a radiation power of 160 mW. The data for the photorefractive
scattering are confirmed by changes in Raman scattering spectra. 相似文献
10.
11.
Maria Vittoria Ciampolillo Annamaria Zaltron Marco Bazzan Nicola Argiolas Cinzia Sada Sabrina Mignoni Marc Fontana 《Applied Physics A: Materials Science & Processing》2011,104(1):453-460
Thermal diffusion from thin film is one of the most widespread approaches to prepare iron doped regions in lithium niobate
with limited size for photorefractive applications. In this work, we investigate the doping process with the aim of determining
the best process conditions giving a doped region with the characteristics required for photorefractive applications. Six
samples were prepared by changing the atmosphere employed in the diffusion treatment in order to obtain different combination
of diffusion profiles and reduction degrees and also to check the effect of employing a wet atmosphere. The compositional,
optical, and structural properties are then extensively characterized by combining Secondary ion Mass Spectrometry, UV, visible
and IR spectrophotometry, High Resolution X-Rays Diffraction, and Micro-Raman Spectroscopy. Moreover, the sample topography
was checked by Atomic Force Microscopy. An analysis of all our data shows that the best results are obtained performing a
double step process, i.e. diffusion in oxidizing atmosphere and subsequent reduction at lower temperature in an hydrogen-containing
atmosphere. 相似文献
12.
Improvement in refractive-index change in LiNbO3:Ce:Cu by applying an external electric field 下载免费PDF全文
By jointly solving two-centre material equations with a nonzero external electric field and coupled-wave equations, we have numerically studied the dependence of the non-volatile holographic recording in LiNbO3:Ce:Cu crystals on the external electric field. The dominative photovoltaic effect of the non-volatile holographic recording in doubly doped LiNbO3 crystals is directly verified. And an external electric field that is applied in the positive direction along the c-axis (or a large one in the negative direction of the c-axis) in the recording phase and another one that is applied in the negative direction of the c-axis in the fixing phase are both proved to benefit strong photorefractive performances. Experimental verifications are given with a small electric field applied externally. 相似文献
13.
Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate 下载免费PDF全文
This paper reports a continuous-wave (CW) mid-infrared intracavity
singly resonant optical parametric oscillator based on periodically
poled lithium niobate (PPLN) pumped by a diode-end-pumped CW
Nd:YVO$_{4}$ laser. Considering the thermal lens effects, it adopted
an optical ballast lens and the near-concentric cavity for better
operation. At the PPLN's grating period of 28.5\,$\mu$m and the
temperature of 140\du, the maximum idler output power of 155\,mW at
3.86\,$\mu$m has been achieved when the 808\,nm pump power is
8.5\,W, leading to an optical-to-optical conversion efficiency of
1.82{\%}. 相似文献
14.
N. V. Sidorov M. N. Palatnikov A. V. Syuy E. A. Antonycheva A. A. Yanichev A. A. Gabain A. A. Kruk 《Optics and Spectroscopy》2014,117(2):315-319
We have investigated the photorefractive (photoinduced) light scattering in lithium niobate single crystals: LiNbO3, LiNbO3:B, LiNbO3:Y(0.46 mas %), LiNbO3:Y(0.24):Mg(0.63 mas %), and LiNbO3:Ta(1.13):Mg(0.0109 mas %) that were grown from congruent melts. We have found that the shape of the speckle structure of this scattering and the kinetics of the development of its indicatrix depend substantially on the type of the impurity dopant in the lithium niobate crystal. We have observed that, upon laser irradiation of crystals doped with Y3+, Ta5+:Mg2+, and Y3+:Mg2+, the shape of their scattering indicatrix changes with time. At the same time, the LiNbO3:B crystal is characterized by a complete absence of time changes in its speckle structure, which indicates that the photorefractive effect in this crystal is substantially lowered. 相似文献
15.
We report on the fabrication and properties of He-implanted waveguides in lithium niobate, which are additionally doped with
copper by using an ion-exchange process. We show that the photorefractive sensitivity in the waveguides is increased by a
factor of 3000.
Received: 23 November 1998 / Revised version: 15 February 1999 / Published online: 12 April 1999 相似文献
16.
E. A. Antonycheva A. V. Syui N. V. Sidorov P. G. Chufyrev A. A. Yanichev 《Journal of Applied Spectroscopy》2010,77(1):80-85
Comparative studies are made of the photorefractive scattering of light in nonlinear single crystals of lithium niobate with
congruent compositions (LiNbO3) doped with "photorefractive" Cu [0.015 mass %] and "nonphotorefractive" Zn [0.5 mass %] cations. For the first time it is
found that single crystals doped with "photorefractive" and "nonphotorefractive" cations have different indicatrices for photorefractive
light scattering. The aperture angle for photorefractive scattering reaches its steady state value more rapidly with high
laser powers than with low. However, at high powers laser induced heating of the crystal is greater, and this leads to a narrowing
of the scattering indicatrix. It is also found that photorefractive scattering in these single crystals depends on the region
of the boule from which a sample has been cut. This indicates that there is a nonuniform distribution over the boule of the
imperfections with localized electrons which determine the magnitude of the photorefractive effect. 相似文献
17.
Iron-doped lithium tantalate crystals are grown by the Czochralski method and their photorefractive properties are examined with holographic methods. Dynamic range, holographic sensitivity, photoconductivity, and dark storage time are measured in dependence on the iron concentration and light intensity. The largest refractive-index change for ordinarily polarized light is 3.5×10-4, in comparison with 6.2×10-4 for iron-doped lithium niobate. Due to a small mobility of protons the dark storage time of holograms in lithium tantalate is larger than that in lithium niobate. PACS 42.40.Pa; 42.70.Ln 相似文献
18.
A novel yellow emitting phosphor Dy3+, Bi3+ co-doped YVO4 potentially for white light emitting diodes 下载免费PDF全文
Novel Y1 x yVO4:xDy3+,yBi3+(0.01 ≤ x ≤ 0.05,0 ≤ y ≤ 0.20) phosphors for light emitting diode(LED) were successfully synthesised by solid-state reaction.The calculation results of electronic structure show that YVO4 has a direct band gap with 3 eV at G.The top of the valence band is dominated by O 2p state and the bottom of the conduction band is mainly composed of O 2p and V 3d states.An efficient yellow emission under near-ultraviolet(365 nm) excitation is observed.Compared with the pure YVO4:Dy3+ samples,the Dy3+,Bi3+ co-doped samples show a more intensive emission peak(at 574 nm) and a new broad emission band(450-770 nm),due to the 4F9/2 6H13/2 transition of Dy3+ and the emission of the VO3 4 Bi3+ complex respectively.The optimum chromaticity index of Y1 x yVO4:xDy3+,yBi3+(0.01 ≤ x ≤ 0.05,0 ≤ y ≤ 0.20) is(0.447,0.497),which indicates that YVO4:Dy3+,Bi3+ has higher colour saturation than the commercial phosphor YAG:Ce3+.The effects of concentration of Dy3+,Bi3+,electric states and the photoluminescence properties are discussed in details. 相似文献
19.
This paper studies the isotopic effect of Cl2+ rovibronic spectra in the A2Πu(Ω=1/2) X 2Πg(Ω= 1/2) system.Based on the experimental results of the molecular constants of 35 Cl2+,it calculates the vibrational isotope shifts of the(2,7) and(3,7) band between the isotopic species 35 Cl+2,35 Cl 37 Cl+and 37 Cl2+,and estimates the rotational constants of both A 2 Π u and X 2 Π g states for the minor isotopic species 35 Cl 37 Cl+and 37 Cl2+.The experimental results of the spectrum of 35 Cl 37 Cl+(3,7) band proves the above mentioned theoretical calculation.The molecular constants and thus resultant rovibronic spectrum for 37 Cl2+ were predicted,which will be helpful for further experimental investigation. 相似文献
20.
A narrow-line diode laser system has been developed for high-resolution spectroscopy of the magnetic quadrupole transition
in ytterbium (Yb) atoms at 507 nm. The system consists of an extended-cavity laser diode at 1014 nm, a tapered amplifier and
a periodically poled lithium niobate nonlinear crystal which converts the wavelength from 1014 nm to 507 nm. We have stabilized
the laser frequency and reduced the linewidth below 1 kHz by tightly locking the laser to a high-finesse optical cavity. By
using the developed laser system, we have successfully observed the ultranarrow
transition in Yb atoms. Furthermore, our simple and compact laser system could be a high performance and portable frequency
reference using iodine spectra whose linewidth becomes less than 50 kHz around 507 nm. We have also demonstrated spectroscopy
of iodine molecules.
PACS 32.30.-r; 07.60.-j 相似文献