An international research team of students and faculty in the Materials Science Department at the University of Arizona and the Chemistry Department at the University of Rennes, France, develops high-efficiency luminescent glass-ceramics by incorporating active rare-earth ions within a very low phonon nanocrystalline environment. Low phonon environments are known to strongly reduce electron-phonon coupling which results in high radiative-emission rates and high fluorescence intensity. Chalcogenide glass-ceramics systems offer the possibility of tuning the environment of active rare-earth ions by incorporating them into a range of heavy alkali-halide or metal-halide nanocrystalline environments. The project builds upon joint expertise in the US and France in the chemistry and thermodynamics of these systems to synthesize and characterize nano-composite materials with high-efficiency fluorescent properties. Another notable advantage of these glass-ceramic is the ability to optimize the optical properties while retaining the formability of the glassy matrix in order to produce fibers. Chalcogenide glass-ceramics posses an extensive transparency over the infrared domain which opens the way for many applications such as telecom amplifiers and mid-infrared laser sources. The chalcogenide glass matrix is then selected such as to offer optimal transparency in the range of rare-earth emission considered for specific applications in the near- and mid-infrared.
This research has the potential to induce a leap forward in infrared photonic technology. High-efficiency luminescent materials open the possibility to develop miniature laser source for lab-on-chip applications or amplifiers for fiber-to-the-home telecom delivery. In particular, with the recent development of OH-free SiO2, the telecom band has opened up from 1.2 to 1.7 microns and consequently requires a wider range of rare-earth emission wavelengths than the conventional Er3+. However, most rare-earth emitters in that critical range such as Pr3+, Tm3+ and Dy3+ are highly inefficient in oxide glasses. Hence the development of low phonon matrixes for these ions will permit to widely improve the capacity of information-carrying telecommunication networks. In addition, this research effort is fully integrated with an international educational program designed to benefit PhD students. Graduates students perform course work and research activities alternately at both universities and obtain a double PhD diploma.
NSF Award ID 0806333 Novel materials for biosensing Outbreaks associated with the contamination of tap water with bacteria or viruses such as rotavirus or norovirus continue to occur in the United States. Hence there is an urgent need for rapid and effective methods of virus collection, detection, and identification for the assurance of water security and quality. In this project we have develop a new family of glass based on Tellurium that is both transparent to infrared light and electrically conductive. This enables the design of sensors that attract the negatively charged viruses on the glass surface by applying an electric field and simultaneously probe them with infrared light. The signal generated by the infrared light is very specific for each micro-organism and we show that it is possible to differentiate between different types of proteins, bacteria and potentially viruses. This technology is promising for on-line, real-time monitoring of water supplies for quality assurance. Novel materials for infrared technology Glasses have long been the material of choice for the design of optical elements such as lenses, fiber or other optical circuits because of and their ability to be easily formed into complex shapes, combined with their outstanding optical transparency. However standard industrial glasses such as building window are only transparent to visible light but are opaque to infrared light. Yet many new optical applications such as night vision, thermal imaging, medical imaging, bio-sensing or missile guidance systems require collection and analysis of infrared light. In this project we have designed new families of glasses with unprecedented transparency in the infrared and analyzed their structure at the atomic scale in order to understand the correlation between their composition and the resulting physical properties of the glassy material. The properties of interest are optical transparency and electrical conductivity but also mechanical resistance. This approach permits to guide and orient the choice of new composition for the design of optimal new materials. Novel materials for laser technology Conventional light sources such as light bulbs are typically multicolor, low intensity and diverge in all direction in space. On the other hand, laser sources are monochromatic (one color/wavelength) high intensity and propagate into a straight light ray. These particular attributes have brought laser sources at the center of many modern technologies ranging from everyday applications such as DVD players to advanced devices for defense or telecommunications. In this project we have produced new materials for the development of high power lasers in the infrared. These infrared lasers have many strategic applications in missile countermeasure and or optical communication, but also in medical imaging or bio-sensing. Our new materials were produced by introducing laser active atoms called rare-earths into an infrared transparent glass. These materials can then be pumped with an excitation light source and show strong light re-emission in the infrared range of interest. These materials are the first step toward the design of high power infrared lasers.
