This Small Business Technology Transfer (STTR) Phase I project will demonstrate a micro-optical distributed sensor technology for temperature, pressure and strain measurements. The measurement principle is based on the detection of optical mode shifts of dielectric micro-beads that serve as sensors. The sensors are weakly coupled to one or more optical fibers and are excited by a tunable laser light. The technology exploits the morphology dependent shifts in resonant frequencies that are commonly referred to as the whispering gallery modes (WGM). A change in a physical condition surrounding the micro-bead "sensor", such as temperature, pressure or force, will cause a change in the size, shape or the dielectric constant of the sensor thereby causing shifts in WGM. With typical quality factors of 106-108, these shifts can be detected with resolutions and dynamic ranges that are beyond those realized by the existing mechanical sensors.
The project will advance understanding of fundamental processes associated with formation of optical modes in weakly coupled micro-resonators in various environments. The technology can have a significant impact on process control in manufacturing industries as well as the medical field. Further, the successful completion of this effort will lay the groundwork for the development of a much broader range of WGM-based distributed sensors that can include species concentration detection with potential applications in homeland security and other areas.
