共查询到20条相似文献,搜索用时 15 毫秒
1.
V. K. Rai 《Applied physics. B, Lasers and optics》2009,95(2):329-333
Upconversion luminescence in triply ionized praseodymium-doped TeO2–Li2O glass using excitation at ∼590 nm into the 1D2 level from a dye laser pumped with the second harmonic of a pulsed Nd:YAG laser has been reported. The mechanism involved
in the upconversion emission observed at ∼480 nm indicates that the most important contribution is energy transfer among praseodymium
ions in pairs followed by the dipole–dipole interaction. The rate-equation model for the emission at ∼480 nm that provides
direct information to determine the energy-transfer rates containing the pair of states involved in the upconversion process
has been explored. 相似文献
2.
The absorption spectra, fluorescence spectrum and fluorescence decay curve of Nd3+ ions in CaNb2O6 crystal were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10−20 cm2 with a broad FWHM of 7 nm at 808 nm for E//a light polarization. The spectroscopic parameters of Nd3+ ions in CaNb2O6 crystal have been investigated based on Judd-Ofelt theory. The parameters of the line strengths Ω
t
are Ω
2=5.321×10−20 cm2,Ω
4=1.734×10−20 cm2,Ω
6=2.889×10−20 cm2. The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 167 μs, 152 μs and 91%, respectively. The fluorescence branch ratios are calculated to be β
1=36.03%,β
2=52.29%,β
3=11.15%,β
4=0.533%. The emission cross section at 1062 nm is 9.87×10−20 cm2. 相似文献
3.
D.-L. Zhang C. Wu Q.-Z. Yang L. Sun Y.-H. Xu E. Y. B. Pun 《Applied physics. B, Lasers and optics》2009,95(2):335-340
Transient characteristics of upconverted emission (560 nm) of Er3+ in LiNbO3 crystals codoped with 0–7.4 mol% MgO were studied under pulse excitation at 800-nm wavelength. The results show that the
transients display considerable Mg-doping-level-dependent nonexponential behavior and a clear Mg optical-damage-resistance
threshold concentration effect. Below the Mg threshold concentration, the lifetime increases slightly with the increased Mg
concentration. Above the threshold, however, the lifetime drops abruptly by 4–7 times and the nonexponential feature becomes
more evident. It is found that each transient can be fitted by a double-exponential function contributed from isolated and
clustered Er3+ sites. The fit parameters show that doping of MgO above the threshold concentration increases the clustered Er site concentration
and the nonradiative cross relaxation probability. The Mg threshold concentration effect derived from the transients is in
qualitative agreement with that from the fluorescence spectrum measured as a function of the Mg concentration. The effect
of the Mg threshold concentration on the clustered Er site concentration is qualitatively explained on the basis of the microscopic
defect model of MgO:LiNbO3 and is conducted with the Mg site change around the threshold concentration. 相似文献
4.
Yanping Wei Chaoyang Tu Guohua Jia Hongyan Wang Fugui Yang Xiuai Lu Jianfu Li Yan Wang 《Solid State Communications》2006,140(5):230-235
crystal with the size up to Φ 13 mm×44 mm was grown successfully by the Czochralski technique and its optical properties were presented. The absorption cross-section and emission cross-section were presented. Also, the potential laser gain near 1.9 μm was investigated. In the framework of the Judd-Ofelt (J-O) theory, the intensity parameters were calculated to be: Ω2=11.375×10−20 cm2, Ω4=5.077×10−20 cm2 and Ω6=6.524×10−20 cm2. The spectroscopic parameters of this crystal such as the oscillator strengths, radiative transition probabilities, radiative lifetime as well as the branching ratios were calculated, too. This crystal is promising as a tunable infrared laser crystal. 相似文献
5.
We report on the experimental observation of the beaming effect in photonic crystals using experimentally mapped spatial field
distributions of energy emitted from a subwavelength photonic crystal waveguide into free-space, rendering with crisp clarity
the diffractionless beaming of energy. Our experimental data agree well with our numerical studies of the beaming enhancement
in photonic crystals with modulated surfaces. Without loss of generality, we study the beaming effect in a photonic crystal
scaled to microwave frequencies and demonstrate the technological capacity to deliver long-range wavelength-scaled beaming
of energy. 相似文献
6.
F. Guo J. Ru H. Li N. Zhuang B. Zhao J. Chen 《Applied physics. B, Lasers and optics》2009,94(3):437-441
Lithium terbium molybdate (LiTb(MoO4)2) single crystal was grown by the Czochralski method. The lattice parameters of the crystal were determined by X-ray diffraction
analysis. The absorption coefficient and the Faraday rotation spectrum (B=1.07 T) were investigated at wavelengths of 400–1500 nm at room temperature. Verdet constants of LiTb(MoO4)2 crystal at 532-, 633- and 1064-nm wavelengths were measured by the extinction method. The results show that LiTb(MoO4)2 crystal has a larger magneto-optical figure of merit than that of terbium gallium garnet at wavelengths of 600–1500 nm. 相似文献
7.
N. Coluccelli G. Galzerano L. Bonelli A. Toncelli A. Di Lieto M. Tonelli P. Laporta 《Applied physics. B, Lasers and optics》2008,92(4):519-523
We present a comparative analysis on the growth, the spectroscopic features, and the cw laser action of room-temperature Yb(5%):LiYF4 (YLF) and Yb(10%):KYF4 (KYF) crystals. Optical slope efficiencies of 33% and 52% have been demonstrated for Yb:YLF and Yb:KYF crystals, respectively.
A remarkable wide wavelength tunability from 1.01 to 1.07 μm has been obtained for both laser crystals. 相似文献
8.
S. Vatnik M. C. Pujol J. J. Carvajal X. Mateos M. Aguiló F. Díaz V. Petrov 《Applied physics. B, Lasers and optics》2009,95(4):653-656
The three thermo-optic coefficients of the biaxial laser host KLu(WO4)2 are measured at 633 nm by a deflection method. Their values at 300 K amount to ∂
n
g
/∂
T=−7.4×10−6 K−1; ∂
n
m
/∂
T=−1.6×10−6 K−1 and ∂
n
p
/∂
T=−10.8×10−6 K−1. Nearly athermal propagation directions are found for polarizations along the N
m
and N
p
dielectric axes. 相似文献
9.
N. A. Tolstik G. Huber V. V. Maltsev N. I. Leonyuk N. V. Kuleshov 《Applied physics. B, Lasers and optics》2008,92(4):567-571
Polarized excited state absorption spectra of Er, Yb:YAB are reported. The Stark levels of the 4I15/2, 4I13/2, and 4I11/2 multiplets of Er3+ have been derived from the measured low-temperature absorption and fluorescence spectra. The stimulated emission spectra
have been calculated using the reciprocity method, and the radiative lifetime of the erbium 4I13/2 level has been determined indicating high nonradiative decay rates. The thermal conductivity of Er-Yb-codoped YAB crystals
has been measured. 相似文献
10.
G. Q. Xie D. Y. Tang W. D. Tan H. Luo S. Y. Guo H. H. Yu H. J. Zhang 《Applied physics. B, Lasers and optics》2009,95(4):691-695
A diode-pumped passively mode-locked Nd: CTGG disordered crystal laser has been experimentally demonstrated for the first
time to our knowledge. Mode locked with a semiconductor saturable absorber mirror, the laser generated 5.2 ps pulses at a
repetition rate of 88 MHz. After intracavity dispersion compensation, the mode-locked pulses were shortened to 4.3 ps. Multiple
emission wavelengths of the Nd:CTGG laser could be synchronously mode locked under dispersion compensation. 相似文献
11.
Kuo-Sheng Kao Shang-Hao Chang Po-Tsung Hsieh Chih-Ming Wang Da-Long Cheng 《Applied Physics A: Materials Science & Processing》2009,96(2):529-533
Three-layered ZnO/Ag–Ti/ZnO structures were prepared using both the sol-gel technique and DC magnetron sputtering. This study
focuses on the electrical and optical properties of the ZnO/Ag–Ti/ZnO multilayers with various thicknesses of the Ag–Ti layer.
The ZnO thin film prepared by the sol–gel method was dried at 300°C for 3 minutes, and a fixed thickness of 20 nm was obtained.
The thickness of the Ag–Ti thin film was controlled by varying the sputtering time. The Ag–Ti layer substantially reduced
the electrical resistivity of the sol–gel-sprayed ZnO thin films. The sheet resistance of the Ag–Ti layer decreased dramatically
and then became steady beyond a sputtering time of 60 s. The sputtering time of Ag–Ti thin film deposition was determined
to be 60 s, taking into account the optical transmittance. Consequently, the transmittance of the ZnO/Ag–Ti/ZnO multilayer
films was 71% at 550 nm and 60% at 350 nm. The sheet resistance was 4.2 Ω/sq. 相似文献
12.
The Tm3+/Er3+:NaGd(MoO4)2 crystal with dimensions of Φ22×30 mm3 was grown by Czochralski method. Polarized spectra and fluorescence lifetime for the 4I13/2(Er3+)→4I15/2(Er3+) transition at room temperature were investigated. Based on the Judd-Ofelt theory, the spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes were calculated. The fluorescence lifetime was measured to be 1.81 ms. The detailed excited-transition mechanism with 800 nm radiation is also discussed. 相似文献
13.
Li Wang Sasa Zhang Qingpu Wang Jiaqi Chen Wei Jiang Ray T. Chen 《Applied Physics A: Materials Science & Processing》2009,95(2):329-334
Photonic crystal based superprism offers a way to design new optical components for beam steering and DWDM (Dense Wavelength
Division Multiplexing) application. Three-dimensional (3D) photonic crystals are especially attractive as they could offer
more control of the light beam. A FCT (Face-Centered-Tetragonal) woodpile structure has been fabricated using layer by layer
stacking techniques with E-Beam lithography. Special planarizations and processes have been introduced to ensure the survivability
and good alignment of the fabricated nanostructures. Scanning electron microscopy results proved the structure uniformity.
With the proper design, the structure exhibits superprism effects around 1550 nm, and such effects have been observed in the
experiments. 相似文献
14.
S. González-Pérez I. R. Martín F. Lahoz P. Haro-González J. Herreros 《Applied Physics A: Materials Science & Processing》2008,93(4):983-986
Local crystalline formation in erbium doped oxyfluoride glass has been obtained under a cw Argon laser irradiation up to 1.8
W pumping power. By exciting at 514 nm, the emission from 800 nm and 850 nm corresponding to the 4S3/2(2H11/2)→4I13/2 electronic transitions have been analyzed both inside and outside the irradiated area. The changes in the emission spectra
indicate that the high power Ar laser irradiation has resulted in a localized desvitrification process. The temperature dependence
of the fluorescence intensity ratio of the 800 nm and 850 nm emission bands has been used to determine the temperature of
the irradiated zone. Moreover, the average lifetime of the 4S3/2(2H11/2) thermalized levels have been measured as a function of the excitation spot position. An important decrease is observed at
the irradiated area. These results confirm that a localized cristalline phase has been created by the laser action. 相似文献
15.
T. P. J. Han E. Cantelar G. Lifante F. Cusso F. Jaque 《Applied physics. B, Lasers and optics》2009,94(2):209-214
This paper reports on the spectroscopy properties, absorption and luminescence, of Cr3+ ions in singly doped, ZnO-codoped, and Zn in-diffused LiNbO3:Cr crystals. In addition to the broad absorption, inter-ionic transitions ascribed to Cr3+ ions located in Li+ and Nb5+ sites; [Cr]Li and [Cr]Nb centres two absorption bands at higher energy are reported and ascribed to the charge transfer transitions of the Cr3+ ions of the two defect centres.
The charge transfer transitions are used as optical probe to study the role of the Zn ions in the Zn in-diffused LiNbO3:Cr samples. It has been observed that the Zn-in-diffused processes created [Cr]Nb centres in the diffusion zone. The location of the diffused Zn2+ ions is considered to be in Li+ site, displacing the Cr3+ ions from the Li+ sites, [Cr]Li, to the Nb5+ positions, [Cr]Nb. 相似文献
16.
N. R. Dhumane S. S. Hussaini V. G. Dongre P. Ghugare M. D. Shirsat 《Applied Physics A: Materials Science & Processing》2009,95(3):727-732
Single crystal of L-Alanine-doped Zinc Thiourea Chloride (ZTC) was grown by slow evaporation technique. L-Alanine was added
in saturated ZTC solution by molar percent. The second-harmonic generation efficiency was studied by Kurtz and Perry powder
SHG test for 1, 2, and 3 mole% L-Alanine-doped ZTC and compared with pure ZTC. We observed enhancement in the SHG efficiency
of L-Alanine-doped ZTC. Higher enhancement was observed for 3 mole% L-Alanine-doped ZTC. Incorporation of L-Alanine in the
crystal was confirmed by energy dispersive X-ray analysis (EDAX). The Fourier transform infrared spectroscopy (FTIR) qualitatively
confirms the presence of all the functional groups. The unit cell parameters and crystal structure were determined by single
crystal X-ray diffraction. The UV-visible absorption spectra of L-Alanine-doped ZTC show excellent transmittance from 300 nm
to 1100 nm. The thermal stability of the grown crystal was also studied by thermo-gravimetric analysis (TGA). 相似文献
17.
B. Denker B. Galagan V. Osiko I. Shulman S. Sverchkov E. Dianov 《Applied physics. B, Lasers and optics》2009,95(4):801-805
A new Bi-doped Mg–Al–silicate glass is suggested and investigated. It can be fabricated by moderate-temperature routine technology.
The characteristic relaxation time of 300–800 μs in combination with the high quantum yield (up to 85%) and wide excitation
spectrum makes this glass a promising laser material. The obtained quadratic dependence of the visible absorption intensity
is an argument in favor of the hypothesis that the absorption and infrared luminescence in Bi-doped glasses are caused by
Bi2 dimers. 相似文献
18.
M. E. Sánchez-Morales G. V. Vázquez E. B. Mejía H. Márquez J. Rickards R. Trejo-Luna 《Applied physics. B, Lasers and optics》2009,94(2):215-219
In this work, we report 1064 nm laser emission in Nd:YVO4 channel waveguides fabricated by carbon implantation. Typical threshold pump powers (∼808 nm) were ≥45 mW. Maximum conversion
efficiency was 11.5% (29.6% slope efficiency), and up to 9 mW of signal was delivered. Sample lengths of 4 mm were sufficient
to completely absorb the pump power. The special spectral characteristics of this material such as broad absorption band and
superior cross sections compared to the YAG crystal makes it suitable for developing compact sources to be integrated in optoelectronic
devices. 相似文献
19.
S. D. Pan X. Q. Yu Z. Yan Y. Shen X. J. Lv S. N. Zhu 《Applied physics. B, Lasers and optics》2008,93(4):749-752
We present an approach to generating a tunable orange laser from 0.601 to 0.604 μm based on a quasi-periodically poled superlattice
in LiTaO3 and a Q-switched 1.064 μm Nd:YVO4 laser as pump. The orange laser was generated in a cavity by a parametric process cascaded by a frequency mixing with a maximum
output of 310 mW using 15 W pump power. 相似文献
20.
S. Klinkhammer T. Woggon U. Geyer C. Vannahme S. Dehm T. Mappes U. Lemmer 《Applied physics. B, Lasers and optics》2009,97(4):787-791
We have theorized that a photonic band gap can be induced in a submicron periodically poled LiNbO3 (SPPLN) with a uniform electrical field applied along the Y axis of the structure. The width of the band gap can be modulated by the intensity of the Y-directional electrical field. Moreover, for such a periodical structure with a duty cycle other than 0.5, the central location
of the gap can be tuned by applying an additional electrical field along the Z axis of the sample. 相似文献