We synthesized bare CdTe and core-shell CdTe/CdS quantum dots (QDs) using 3-mercapto propanoic acid as stabilizer
by an improved method in aqueous solutions. The optimum conditions for preparation of highly luminescent bare CdTe
QDs (CdTe core) were investigated and proposed to be pH 7.0 and 3h of refluxing under room temperature.
Transmission electron microscopy (TEM) image showed well dispersed particles, and the average QDs size was c.a. 2.5
nm determined via TEM. The quantum yield (QY) of CdTe QDs for photoluminescence was calculated, and 51.4% of
QY can be achieved without any further purification. Furthermore, we capped the bare CdTe with CdS semiconductor
materials and produced luminescent core-shell CdTe/CdS QDs. Three processes were evaluated to obtain the best QY of
core-shell CdTe/CdS QDs. Process 2 and 3 reached 14.9% and 14.5% of QY after 19h and 0.5h of refluxing
respectively, both results are better than that of 2.5% of QY and 52h of refluxing in process 1. Red-shift of maximum
emission wavelength (from 551 nm to 680 nm), observed from fluorescence spectrum, revealed the formation of core-shell
A series of LiNbO3 crystals doped with different levels of In2O3 were grown by Czochraski method. The photo-damage threshold as well as infrared transmittance spectra and doubling frequency conversion efficient of the crystals was measured. At the same time, the shift mechanism of OH- absorption peaks in In:LiNbO3 crystals were investigated. In the experiment of frequency doubling, it was found that the phase-matching temperature of In:LINbO3 crystals was lower than that of Mg:LiNbO3 and Zn:LiiNbO3 crystals.
The LiTaO3 crystal doped with 0.03 wt% Fe2O3 was grown in a diameter-controlled Czochraski equipment using Si-Mo bar heater furnace. The photo-damage resistance ability, exponential gain coefficient, diffraction efficiency and response time of Fe:LiTaO3 and Fe:LiNbO3 crystals were measured. The measured results showed that the photo-damage resistance ability of Fe:LiTaO3 crystal was as much as 5 times higher than that of Fe:LiNbO3, the response speed of Fe:LiTaO3 crystal was improved one order of magnitude than that of Fe:LiNbO3, and the exponential gain coefficient and diffraction efficient of Fe:LiTaO3 crystal were smaller than that of Fe:LiNbO3, respectively. Using Fe:LiTaO3 crystal as recording medium, the obtained image was clear and complete in the holographic associative memory experiment using self-pump phase conjugate reflector.