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21.
We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4-3.0 MeV and doses of 1015 ions/cm^2. The dark-line spectroscopy properties are investigated by a prism-coupling method. With an effective refractive index method, the refractive index profiles of the waveguides are reconstructed. The program code TRIM'98 (transport of ions in matter) is used to simulate the implantation process of oxygen ions into the KTiOPO4 crystal. It is found that an inherent relationship exists between the nuclear damage and the refractive index changes induced by the ion-beam implantation. 相似文献
22.
We report the properties of a compact diode-pumped continuous-wave Nd:GdV04 laser with a linear cavity and different Nd-doped laser crystals. In a 0.2at.% Nd-doped Nd:GdVO4 laser, 1.54 W output laser power is achieved at 912nm wavelength with a slope efficiency of 24.8% at an absorbed pump power of 9.4W. With 0.3at.% Nd-doping concentration, we can obtain the either single-wavelength emission at 1064nm or 912nm or the dual-wavelength emission at 1064nm and 912nm by controlling the incident pump power. From an incident pump power of 11.6 W, the 1064nm emission between ^4Fa/2 and ^4I11/2 is suppressed completely by the 912nm emission between ^4Fa/2 and ^4I9/2. We obtain 670 mW output of the 912nm single-wavelength laser emission with a slope efficiency of 5.5% by taking an incident pump power of 18.4 W. Using a Nd:GdV04 laser with 0.4at.% Nd-doping concentration, we obtain either the single-wavelength emission at 1064nm or the dual-wavelength emission at both 1064nm and 912nm by increasing the incident pump power. We observe a strong competition process in the dualavelength laser. 相似文献
23.
Q. Yang S. Lin L. Xu F. Yang Y. Yang L. Pan C. Sun Y. Li G. Sun Z. Jiang 《Applied physics. B, Lasers and optics》2005,80(8):953-955
The observations of three-photon-induced frequency-upconversion fluorescence and the highly directional stimulated visible emission in two dyes, 4-[p-(dicyanoethylamino) styryl]-N-methylpyridinium iodide (abbreviated as CEASP) and the complex of CEASP and Ce(NO3) (abbreviated as CEASP-Ce), are reported. The photographs of the forward amplified spontaneous emissions spots, pumped by an optical parametric oscillator idler with a pulse width of 8 ns and a wavelength of 1.3 μ m, are shown. The upconversion fluorescence produced both in dimethyl formamide solution and 2-hydroxyethyl methacrylate (HEMA) polymer spans from green to red, with a cubic dependence on the pump light intensity. The experimental results imply that the existence of the lanthanide ion Ce3 + sensitizes the nonlinear absorption and emission. 相似文献
24.
Xiaodong Xu Pingxin Song Guoqing Zhou Jun Xu Peizhen Deng 《Solid State Communications》2004,129(11):717-720
Cr4+:YbAG (Cr4+:Yb3Al5O12) crystal with a size up to Φ24 mm×30 mm was grown by the Czochralski method. In the absorption spectrum, there are two absorption bands at 939 and 969 nm, respectively, which are suitable for InGaAs diode laser pumping, and there is an absorption band at 1030 nm, which is suitable for passive Q-switched laser output at 1.03 μm. A broad emission spectrum from 970 to 1100 nm was exhibited from 940 nm wavelength pumping. This crystal is promising as a self-Q-switched laser crystal used for compact, efficient, highly stable, passive self-Q-switched thin chip solid-state lasers. 相似文献
25.
N. N. Il’ichev A. V. Kir’yanov V. P. Shapkin S. A. Nasibov S. Ye. Mosaleva 《Applied physics. B, Lasers and optics》2005,81(1):83-91
An experimental study and theoretical modeling of the nonlinear change in refractive index of a Co2 +: ZnSe crystal at the short-pulse single-beam probing at the wavelength 1.54 μm is reported. In the experimental conditions of negligible contributions in the index non-linearity stemming from the Kerr-effect and inhomogeneous heating, the nonlinear change in refractive index in Co2 +:ZnSe is shown to be caused by the resonant Co2 + population-perturbation effect (i.e., by the Co2 + ground-state absorption saturation). The Z-scan single-beam technique and novel theoretical approach addressing the resonant nonlinear refraction in a saturable doped medium are used, respectively, for an experimental and theoretical inspection of the phenomenon. For a set of Co2 +:ZnSe samples with different concentrations of Co2 + ions at the short-pulse (200 ns) mJ-range probing, we show that the maximal nonlinear change in refractive index is about of units of 10− 4 at the chosen wavelength. 相似文献
26.
J. Šonský J. Lančok M. Jelínek J. Oswald V. Studnička 《Applied Physics A: Materials Science & Processing》1998,66(5):583-586
3 (YAP) thin films as a promising material for application in a planar waveguide laser has been studied. The films have been
grown on sapphire(0001) and YAP(001) substrates by laser ablation. The influence of the substrate temperature and ambient
oxygen pressure on the crystalline structure, concentration of Nd incorporated into films, and consequent luminescence spectra
were investigated. The waveguiding properties were observed and refractive index of the films was evaluated.
Received: 8 February 1998/Accepted: 9 February 1998 相似文献
27.
A. Di Lieto P. Minguzzi A. Toncelli M. Tonelli H. P. Jenssen 《Applied physics. B, Lasers and optics》1996,62(5):443-447
We describe the continuous-wave (cw) operation of a LiYF4 laser based on crystals doped with different concentrations of Tm3+. We observed the fluorescence spectra from the upper laser level when the crystal is placed inside the laser resonator, in the same optical environment of the coherent emission. We measured the laser intensity as a function of pump power and obtained a 24% slope efficiency by selecting a suitable orientation of the crystal. Using all this information, we were able to demonstrate laser tunability at 1.9 µm in a 50 cm–1 wide interval. 相似文献
28.
We use a multispeckle diffusing wave spectroscopy (MSDWS) method to study the ensemble-averaged dynamics of the fluctuating
speckle pattern when illuminating colloidal particles suspended in a static and opaque porous medium with a coherent light
source. Experiments were performed with Brownian latex particles in a random packing of glass spheres. The mixing of the light
scattered by the moving colloidal particles and the porous matrix gives rise to a plateau value of the intensity autocorrelation
function in the long-waiting-time limit. From the plateau in the correlation function, we can determine the fraction of light
scattered from moving particles and estimate the photon mean free path in the colloidal solution. The method opens up promising
possibilities to probe the static fraction in semisolid materials. 相似文献
29.
Saeed Ghanbari P. Blair Blakie Peter Hannaford Tien D. Kieu 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(3):305-310
The accessibility of the critical parameters for the superfluid to Mott insulator quantum phase transition in a 2D permanent
magnetic lattice is investigated. We determine the hopping
matrix element J, the on-site interaction U, and hence the ratio J/U, in the harmonic oscillator wave function approximation.
We show that for a range of realistic parameters the critical values of J/U, predicted by different methods for the Bose-Hubbard
model in 2D, such as mean field theory and Monte Carlo simulations, are accessible in a 2D permanent magnetic lattice. The
calculations are performed for a 2D permanent magnetic lattice created by two crossed arrays of parallel rectangular magnets
plus a bias magnetic field. 相似文献
30.
W. J. Guo Y. F. Lin X. H. Gong Y. J. Chen Z. D. Luo Y. D. Huang 《Applied physics. B, Lasers and optics》2009,94(1):155-163
A Pr3+:NaGd(MoO4)2 single crystal has been grown by the Czochralski method. The polarized absorption spectra, polarized fluorescence spectra,
and fluorescence decay curves of the crystal were measured at room temperature. The Judd–Ofelt intensity parameters Ω
t,q
(t=2,4,6) and the spectroscopic parameters related to the 3
P
0 and 1
D
2 multiplets were obtained and analyzed. The decay mechanisms for the 3
P
0 and 1
D
2 multiplets were also discussed. 相似文献