We are working on optical properties of rare earth doped glasses, ceramics and nanophosphors since few years. The interesting results obtained during this period are-
(a) Research achievement on Glassy materials
We have developed tellurite and silica glasses with two or three rare earths simultaneously in host. This enabled us to get
(i) Color tuned visible/white light emission from glass on NIR pumping<
(ii) We get extreme UV and visible upconverted radiation on NIR pumping through energy transfer. Some of these emissions also show a tendency of lasing.
(iii) Some of these glasses serve the purpose of the temperature sensor, humidity sensor etc. These results have been published in different journals.
(b) Research achievement on ceramic materials
Rare earth doped borate silicate tellurite glass when heated to appropriate temperature, ceramics are formed. These ceramics in some cases are transparent whereas in other cases they are semi transparent or opaque. An important thing is that nanocrystals develop on its surface or inside. This enhances the fluorescence intensity of the rare earth many fold. We have tried to locate the position of rare earth ion whether it is inside the crystal or on the surface near by or far away from the crystal. It is found that it varies from host to host and also on heating temperature. These results have been published in different journals.
(c) Research achievement on phosphor materials
We have developed rare earth doped nanophosphors using various techniques. Some of these are Gd2O3, La2O3, MAl2O3(M=Ca, Ba, Sr, Mg) hosts. Several rare earth species (Er, Yb, Tm, Ho, Eu, Tb etc) have been doped and their optical properties have been studied. These phosphors show very interesting optical properties. Gd2O3: Er, Yb based phosphor has been found suitable for different applications such as temperature sensor, bioimaging, fingerprint detection, optical switching, optical bistability and also as optical nano heater. Optical heating property is improved in La2O3 based phosphor. Aluminate based phosphor have been found suitable for the interconversion of Tb3+ and Tb4+ in suitable condition. Similar thing is also observed in case of Yb in +2 and +3 state exist together. In addition, we have also prepared metal (Bi, Cu, Si, Au etc) nanoparticles in different media using laser ablation and studied their different properties.