Upconversion in rare-earth ions is a sequential multiphoton process that efficiently converts two or more low-energy
photons, which are generally near infrared (NIR) light, to produce anti-Stokes emission of a higher energy photon (e.g.,
NIR, visible, ultraviolet) using continuous-wave (cw) diode laser excitation. Here, we show the engineering of novel,
efficient, and biocompatible NIRin-to-NIRout upconversion nanoparticles for biomedical imaging with both excitation and
emission being within the “optical transparency window” of tissues. The small animal whole-body imaging with
exceptional contrast (signal-to-noise ratio of 310) was shown using BALB/c mice intravenously injected with aqueously
dispersed nanoparticles. An imaging depth as deep as 3.2-cm was successfully demonstrated using thick animal tissue
(pork) under cw laser excitation at 980 nm.
In our conduction traditional polarization technology, it is difficult to make the doping ions distribute uniformly. The alternative polarization technique is used to make the Fe3+ and Fe2+ distribute uniformly in the doped LiNbO3 crystals by controlling polarization temperature, polarization time and polarization current. The properties of the crystals are improved greatly.
Doping ZnO with the concentration of 3mol% and 7mol% in Ce:Mn:LiNbO3, respectively, Zn:Ce:Mn:LiNbO3 crystals were grown by Czochralski method. The optical damage resistance ability of crystals was measured. The optical damage resistance ability of Zn (7mol%):Ce:Mn:LiNbO3 crystal is two orders magnitude higher than that of Ce:Mn:LiNbO3 crystal. The exponentional gain coefficient, diffraction efficiency, response time and effective charge concentration were also obtained. The response speed of Zn(3mol%):Ce:Mn:LiNbO3 and Zn(7mol%):Ce:Mn:LiNbO3 crystal is two times and four times higher than that of Ce:Mn:LiNbO3, respectively. The mechanism of optical damage resistance ability of Zn:Ce:Mn:LiNbO3 crystal was researched.
CeO2 and MnCO3 codoped Potassium Lithium Niobate single crystals were grown by the Czochralski method. It was shown that Ce ions would be precedently substituted for the site of K by the absorption spectra and X-ray diffraction patterns. Otherwise Mn would be substitute for the site of Nb. The response time, exponential gain coefficient and effective carries density was measured by the two beam coupling. The effect of Oxide and reduced treatment on these parameters was researched.
The preparation of polycrystalline GaAs films by using electrodeposition technology is described. Influences of electrodeposition parameters on the quality of films were discussed, such as the current density, the relative concentration of ions, the value of pH of the electrolyte. On the basis of observing the micrographs, we have measured the chemical composition, microstructure and parameters of the energy band of the films. The result show that the composition of the films deposited is Ga0.9946 As1.0054, and the direct gap nature of the deposited material, its band gap is 1.40eV.
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