Laser/Optical Materials Research Group
Current Research Students:
Leanne Lortie '06
Charlotte Hau-yiu Wong '05
Nicholas Roberts-Warren '07
Jessica Tolson '07
Phuentsho Wangmo '07
Recent Research Focus
-- Novel ceramic materials for microchip and high power ceramic lasers:
Ceramic laser materials have recently received a lot of attentions because they are potentially great candidates for high-efficiency microchip or high power lasers. Contrast to popular single-crystal laser materials such as the rare-earth ion Nd doped single crystal YAG, ceramic materials are easy to be fabricated into large size and can accommodate high rare-earth ion (laser ion) concentrations. The first ceramic laser output was obtained in 1995 in Nd:YAG, and the first Yb:Y2O3 ceramic laser was just demonstrated in April 2003. To make ceramic lasers possible, the ceramic materials have to be made highly transparent with very low porosity and scattering loss. Recently, we are working on a new kind of transparent ceramic materials, for example: Er-doped Pb1-xLaxZryTi1-y03 (PLZT), for possible high-efficiency microchip or high-power laser applications. We concentrate on optical studies of this newly developed rare-earth ion doped PLZT and other lead-based ceramic materials. Our studies can provide crucial information for promising applications in new optical devices including PLZT ceramic lasers. This research has being supported by National Science Foundation and Wheaton Research Partnership Program
-- Rare-earth ion doped laser crystals:
The most prominent rare earth ion in laser applications is trivalent neodymium (Nd) ion, which yields strong emission at wavelengths around 0.9, 1.0 and 1.3 micon when doped in a variety of hosts. Crystals with garnet structure are popular laser hosts for Nd ions. For example, the single crystal Nd:YAG has served over forty years as the most important solid-state laser material. Fluoride crystals are also found to be good hosts for Nd ions such as Nd:YLF. The Nd lasers have found many important applications such as laser radar and remote sensing. One of the recent efforts in NASA is to develop Nd laser systems that can produce a laser line at 0.94 micron for remote sensing of water vapor (H2O) in the atmosphere because water has a strong absorption line right at 0.94 micron. It is crucial to know how the Nd line positions and widths change with the host and temperature for efficient and effective Nd laser applications. The work on Nd doped laser crystals is to investigate thermal line position tuning (shift) and broadening of the Nd luminescence lines in different host crystals, focusing on garnet and fluoride hosts. Most of the crystals used in the study were provided by NASA.
-- Upconversion energy transfer processes in laser materials:
Upconversion phenomena have been studied actively in rare-earth ion doped laser solids. Typical rare-earth ions that are good for upconversion are Er, Tm, Ho, Pr, and Nd ions. The rare-earth ion Yb is often co-doped with some of these ions because it can help absorb energy efficiently and enhance the upconversion process. One of the most important applications of upconversion is to make upconversion lasers, which generally emit light that has higher photon energy than the pump photon energy. The research is to study the temperature and concentration dependence of upconversion processes in rare-earth ion doped laser solids, including single crystals and ceramics.
Experimental
Our research involves intensive experimental work, including the measurement of photoluminescence, absorption, transmission, reflectance, excitation, and lifetime over a wide range of temperatures. Measurement equipment includes lasers and other light sources from UV to IR, monochromators, spectrographs, light detectors, electronics, and computer date acquisition system.
Contact Information
Xuesheng Chen
Professor
Dept of Physics and Astronomy
Wheaton College, Norton, MA 02766
508-339-0278
xchen@wheatonma.edu