共查询到20条相似文献,搜索用时 0 毫秒
1.
I. Sokólska 《Applied physics. B, Lasers and optics》2000,71(2):157-162
LaGaO3 crystals doped with Er3+ ions were grown by the Czochralski method and their optical properties were examined. The Er3+ energy levels have been determined from the low-temperature absorption and emission spectra. The results of Judd–Ofelt analysis
are presented and compared with experimental data. The emission cross sections are determined for the 4
I
13/2→4
I
15/2 (1.55 μm) and 4
I
11/2→4
I
13/2 (2.85 μm) transitions of erbium.
Received: 6 December 1999 / Revised version: 10 February 2000 / Published online: 27 April 2000 相似文献
2.
J.P. Salvestrini J. Zaccaro A. Ibanez M.D. Fontana 《Applied physics. B, Lasers and optics》1998,67(6):761-763
Received: 28 September 1998 相似文献
3.
P. Fita K. Smoliński Z. Gołacki K. Lawniczak-Jablonska 《Applied Physics A: Materials Science & Processing》1999,68(6):681-685
The homogeneity, solid solubility, and chemical bonds in the new materials PbTe, SnTe doped with Ce were investigated. Scanning
electron microscope observation and electron probe microanalysis carried out on PbTe crystals doped with Ce, revealed three
types of Ce-rich precipitates with following compositions: CeTe2, Ce3Te7, Ce2Te5 and small admixture of PbTe in precipitates. The solubility of Ce in PbTe matrix was estimated as 0.5±0.1 at. %. The solubility
of PbTe in CeTe2 and Ce3Te7 was found to be 3±0.5 at. %, but 7±0.5 at. % in the case of Ce2Te5. In SnTe crystal doped with Ce only one kind of precipitate with composition Ce2SnTe5 was found. Cerium solubility in SnTe matrix was estimated to be 1±0.25 at. %. According to our knowledge this is the first
report of the identification of Ce2SnTe5 compound. The similar compounds Ce2SnS5 and Ce2SnSe5 are known.
Received: 9 December 1998 / Accepted: 9 February 1999 / Published online: 28 April 1999 相似文献
4.
4 Ti3O12. Basic properties of absorption gratings in this crystal are investigated with beam-coupling experiments. Depending on the
grating spacing, wavelength, and intensity of the writing beams, an absorption grating in our sample can be either in phase
or shifted by 180° with respect to the light pattern. The formation mechanism of absorption grating is discussed and proposed
to originate from a shallow-trap effect.
Received: 10 February 1997 相似文献
5.
M. Luennemann U. Hartwig G. Panotopoulos K. Buse 《Applied physics. B, Lasers and optics》2003,76(4):403-406
The electrooptic effect in lithium niobate crystals (LiNbO3) for extremely high externally applied electric fields of up to 65 kV/mm is investigated. Homogeneous electrooptic refractive-index
changes of up to 4.8×10-3 are found for ordinarily polarized light. No quadratic electrooptic effect is observed. An upper bound for the quadratic
electrooptic coefficient of |s13|≤2.3×10-21 m2/V2 is determined. Electrooptic, angular, and wavelength tuning of the Bragg condition of a thermally fixed hologram are demonstrated.
Received: 29 October 2002 / Revised version: 14 January 2003 / Published online: 26 March 2003
RID="*"
ID="*"Corresponding author. E-mail: ml@uni-bonn.de 相似文献
6.
A sensitive and simple pulsed surface thermal lens (TL) technique is used in situ to investigate the laser conditioning and
to measure the nonlinear absorption of LaF3/MgF2 dielectric multilayers deposited on CaF2 substrates at 193 nm. Due to the high single-shot sensitivity of the surface TL technique, the laser conditioning can be
monitored from the first shot of irradiation on a shot-by-shot basis. The LaF3/MgF2 multilayers show a very strong conditioning effect. The ratio of the absorption before and after the laser irradiation is
in the range 4–8 for a highly reflective (LH)20 LaF3/MgF2 multilayer, and 3–4 for (1L3H)7 and (3L1H)7 multilayers. In comparison, a (LH)20 LaF3/AlF3 multilayer shows only a weak conditioning effect, with an absorption ratio of approximately 1.4. Our experimental results
suggest that the strong conditioning effect of the LaF3/MgF2 multilayer is due to the absorption conditioning of the LaF3 layers. However, the MgF2 layers are shown to be responsible for the considerable increase in LaF3 absorption as well as the ability to condition the absorption. The fluoride multilayers present non-negligible nonlinear
absorption and the two-photon absorption coefficient of the multilayers is estimated to be approximately 5×10-7 cm/W.
Received: 11 December 2000 / Accepted: 20 February 2001 / Published online: 25 July 2001 相似文献
7.
D. Bravo A. Martín J. J. Carvajal M. Aguiló F. Díaz F. J. López 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(3):237-242
An electron paramagnetic resonance (EPR) study of Er3+
ions in single crystals of RbTiOPO4 (RTP) is presented. The EPR
spectra show the existence of six different Er3+ centres. The
g-matrix has been determined for these centres from the
analysis of the angular dependences of the spectrum in three planes of the
crystal. The study supports that erbium can enter the Rb+ and Ti4+
low-symmetry sites of RTP. This conclusion differs from those for
KTP:Er3+ and RTP codoped with Nb and Er. The different occupancies
found for Er in these various crystals is suggested to be due to the
differences in Er concentration. 相似文献
8.
A. Righi J.P. Salvestrini P. Bourson R.L. Moreira M.D. Fontana 《Applied physics. B, Lasers and optics》1998,67(5):559-562
1-x RbxSO4 for x varying between 0 and 0.50 were investigated by an ac modulation method based upon the Sénarmont arrangement. The electro-optic
coefficient rc, and for the first time the coefficients r41 and r51 were determined with good accuracy in pure LiKSO4 around room temperature at a wavelength of 633 nm. The frequency dependence of the electro-optic coefficient rc was measured in the frequency range from 1 kHz up to 1 MHz. The values of the factor of merit ne
3rc of the mixed crystals LiK1-xRbxSO4 were obtained for the first time, for the concentrations x=0.05, 0.10, 0.20, and 0.50. The electro-optic properties are shown
to be affected by the random presence of the rubidium ions in this disordered system.
Received: 16 March 1998/Revised version: 2 June 1998 相似文献
9.
Additive-pulse mode locking of a diode-pumped Nd3+:YVO4 laser 总被引:2,自引:0,他引:2
We demonstrate self-starting additive-pulse mode locking of a diode-pumped Nd3+:YVO4 laser. Pulse durations of 2.7 ps are measured at a repetition frequency of 90.7 MHz and at an average output power of 1.1 W.
This corresponds to a peak power of 4.5 kW.
Received: 27 June 2001 / Revised version: 10 October 2001 / Published online: 29 November 2001 相似文献
10.
Light–induced charge transport processes in photorefractive barium titanate crystals doped with iron
A. Mazur U. van Stevendaal K. Buse M. Weber O.F. Schirmer H. Hesse E. Krätzig 《Applied physics. B, Lasers and optics》1997,65(4-5):481-487
3 ) are annealed in a hydrogen atmosphere at various temperatures. After these reducing treatments, absorption, light–induced
absorption changes, two–beam coupling direction, photo electron paramagnetic resonance (photo EPR), dark and photoconductivity
as well as bulk photovoltaic current density are investigated. The samples are electron conductive and the charge transport
is governed by only one level, which is identified by photo EPR as Fe2+/Fe3+. The photoconductivity exceeds the dark conductivity for intensities above 1 kWm-2. A relation between the absorption constant and the Fe2+ concentration is derived. From the known charge transport parameters the advantageous photorefractive properties of optimized
reduced BaTiO3:Fe are deduced; possible response times in the millisecond range at an intensity of 10 kWm-2 are estimated.
Received: 22 January 1997/Accepted: 23 January 1997 相似文献
11.
X. Chen 《Applied Physics A: Materials Science & Processing》1999,69(4):453-455
We have observed a new polarisation pattern in terbium gallium garnet which is both laser excited and mechanically stressed.
The pattern can be characterized by a splitting from a “one dot” structure to a “two dots” structure. We have found that the
new pattern is very sensitive to the orientation and the strength of the external forces applied to the sample. Thanks to
this sensitivity and to the image simplicity, this new effect may be used in a vectorial force sensor and actuator.
Received: 25 March 1999 / Accepted: 20 April 1999 / Published online: 25 August 1999 相似文献
12.
A new approach to the intrinsic and extrinsic defect subsystems, considering them as one integrated functional system, is
developed for complex oxides. The strong interrelation of these subsystems becomes especially apparent when concentrations
of both defect classes are comparable. A new parameter, reflecting the total intrinsic defect concentration, is introduced
to determine the degree of crystal imperfection. The necessity of at least two calibrated samples – congruent and regularly
ordered crystals – is substantiated. The accuracy by which the parameter can be determined can serve as a criterion in comparison
of different methods of crystal characterisation. A procedure for crystal calibration by several physical characteristics
is illustrated. Such a heuristic generalisation of the concept of mutual correlation of the whole defect system and the material
only became possible on the basis of experimental and theoretical study of large numbers of LiNbO3 crystals. The spectra of EPR, NMR, ENDOR, and other properties of crystals with different compositions, diverse modifiers
(K, Mg,...), and various probe impurities have been analysed. It is found that crystals with vanishingly small concentration
of intrinsic defects offer extraordinary informative opportunities. Their micro- and macroscopic properties are discussed.
The developed ideas have a general character; therefore they should also be valid for other non-stoichiometric complex oxides.
Received: 3 December 1998 / Revised version: 15 February 1999 / Published online: 12 April 1999 相似文献
13.
14.
V. Uhl K.O. Greulich S. Thomas 《Applied Physics A: Materials Science & Processing》1997,65(4-5):457-462
′ and NBOH). Samples with high OH content exhibit gradual recovery from the absorption band within several minutes after exposure
to the KrF laser radiation.
The formation of the KrF laser-induced 210 nm absorption band depends on the fictive temperature and on the OH content. Low
fictive temperature, as a measure for the number of intrinsic defects, retards E′ generation at the beginning of intense KrF excimer laser irradiation when the majority of defects are generated from precursor
defects. However, for longer irradiation periods with pulse numbers of the order of 105 pulses, a high OH content is the beneficial parameter. The accompanying atomic hydrogen is essential for the suppression
of the 210 nm absorption band. This happens by transformation of the E′ centers into Si-H defects.
In contrast to a generally held view, annealing (decreasing of the fictive temperature) of fused silica does not always reduce
UV induced defect generation. For example, annealing of the samples in an argon atmosphere causes a significantly higher 210 nm
absorption increase during KrF excimer laser irradiation (240000 pulses) compared to nonannealed samples.
Two spectroscopic methods to determine the OH content of fused silica were applied: Raman and infrared spectroscopy, which
in this work lead to differing results.
The energetics of the 210 nm absorption band generation and bleaching is summarized by a diagram explaining the interaction
of the 248 nm laser radiation with fused silica.
Received: 2 June 1997/Accepted: 13 June 1997 相似文献
15.
3 :Ti:Fe waveguides are thermally fixed during hologram recording at elevated temperatures. Different guides are fabricated
by titanium indiffusion using iron-doped and nominally pure y-cutLiNbO3 substrates and characterization is performed by dark-mode spectroscopy. The refractive index modulation of gratings written
and simultaneously fixed at 180 °C is investigated as a function of propagation depth, titanium and iron concentration. The
experimental results are compared with those obtained for unfixed holograms recorded at room temperature.
Received: 21. July 1997/Revised version: 13 October 1997 相似文献
16.
K. Chah M.D. Fontana M. Aillerie P. Bourson G. Malovichko 《Applied physics. B, Lasers and optics》1998,67(1):65-71
3 along the ferroelectric c axis in pure and chromium-doped crystals. We have studied four series of samples with various crystal
compositions and doping concentrations to separate the influence of the intrinsic defects related to the non-stoichiometry
and the effect of the introduction of chromium. In pure and slightly doped crystals, the electro-optic coefficient rc shows a non-monotonous dependence on the controlled crystal composition, which reflects a similar behaviour of the corresponding
dielectric permittivity. In the highly Cr-doped crystals rc displays a large decrease with increasing Cr concentration whatever the crystal composition. The results have been discussed
by means of the LiNbO3 structure and the substitution site dynamics.
Received: 14 November 1997/Accepted: 2 January 1998 相似文献
17.
The complete set of self-consistent parameters of nominally undoped LiNbO3 crystals of congruent composition that describe the electro-optic, piezoelectric, elasto-optic, elastic, and dielectric response
has been determined by numerically evaluating available measurements. The parameters were determined at room temperature and
consist of the low-frequency clamped dielectric constants εS
ij, elastic stiffness constants at constant electric field CE
ijkl, piezoelectric stress coefficients eijk, elasto-optic constants at constant electric field pE
ijkl, and clamped electro-optic coefficients rS
ijk. It is shown that the complete set is required for calculating the effective electro-optic coefficients and dielectric constants
in photorefractive applications of LiNbO3.
Received: 4 January 2002 / Revised version: 1 February 2002 / Published online: 14 March 2002 相似文献
18.
An analytical model is developed to study the influence of the Auger upconversion process on the thermal loading under lasing
and nonlasing conditions. With the developed model, Auger upconversion rates can be determined by comparing theoretical calculations
with experimental results for the ratio of the thermal loading under lasing and nonlasing conditions. The upconversion rates
obtained with the present method are compared with the results measured from the fluorescence decay experiment.
Received: 7 June 1999 / Revised version: 3 August 1999 / Published online: 30 November 1999 相似文献
19.
F. Chen X.-L. Wang Q.-M. Lu G. Fu S.-L. Li K.-M. Wang D.-Y. Shen R. Nie 《Applied physics. B, Lasers and optics》2002,75(8):895-897
Planar waveguides were formed in Nd:YVO4 crystals by 3.0-MeV Si+-ion implantation at doses of 1×1013–1.5×1015 ions/cm2 at room temperature. The effective refractive indices of the waveguide propagation modes were measured by using a prism-coupling
method. It was found that the number of the propagation modes is dependent on the doses for the waveguides in Nd:YVO4. The atom displacement in the near-surface region (about 2 μm beneath the surface) of the Nd:YVO4 crystal induced by the implantation was simulated by using the TRIM 98 (transport and range of ions in matter) code. The
possible reasons for the waveguide formation are discussed in a primary way.
Received: 17 July 2002 / Revised version: 20 September 2002 / Published online: 11 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-531-8565167, E-mail: drfchen@sdu.edu.cn 相似文献
20.
M. Jazbinšek M. Zgonik S. Takekawa M. Nakamura K. Kitamura H. Hatano 《Applied physics. B, Lasers and optics》2002,75(8):891-894
The wavelength dependence of the space-charge field as induced in near-stoichiometric LiTaO3 crystals is investigated by measuring the bulk photogalvanic effect and the photoconductivity. LiTaO3 crystals of composition nearer to stoichiometry exhibit a pronounced reduction of the saturated space-charge field, which
results from a larger increase in the photoconductivity relative to the photogalvanic effect. Especially, at near-UV wavelengths,
the saturated space-charge field of the order of 0.1 kV/cm reaches a minimum that is two orders of magnitude lower than typical
values observed in undoped near-stoichiometric LiNbO3.
Received: 11 July 2002 / Revised version: 2 September 2002 / Published online: 20 December 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1056, E-mail: mojca@fiz.uni-lj.si 相似文献