Albert T. Rosenberger, Donna K. Bandy, Bret N. Flanders Department of Physics, Oklahoma State University
Intellectual Merit: This project investigates ultralow-threshold lasing of individual fused-silica microspheres coated with semiconductor quantum dots. The pump laser input and the microlaser emission are coupled in and out of the microsphere's whispering-gallery modes by tapered optical fibers. The objectives are to: (1) advance the understanding of microlaser operation, through studies of the origin of such low thresholds; (2) extend the range and controllability of microlaser operation - for example, increasing the 1240-1780-nm lasing wavelength range observed with HgTe and HgCdTe by varying the size and composition of the nanoparticles (also using PbSe and PbS); (3) further develop dielectrophoretic methods for controlled coating of microresonators with nanoparticles; and (4) demonstrate practical application of these microlasers - for example, the sensing of atmospheric trace gases such as methane or carbon monoxide. Three exciting new areas of research are resonant optical enhancement in microspheres; efficient optical emission from semiconductor nanoparticles; and directed assembly of nanoparticles into structures using dielectrophoresis. This work will advance fundamental research by facilitating studies of cavity quantum electrodynamics using quantum dots and whispering-gallery modes.
Broader Impacts: This work will strengthen ties with the Oklahoma Network for Nanostructured Materials (NanoNet). The University's multidisciplinary Photonics degree program will also benefit from this project. Both the NanoNet and the Photonics program recruit students from underrepresented groups, and the PIs will encourage the participation of undergraduates. One co-PI and one graduate student are members of underrepresented groups. The graduate students involved will learn fundamental techniques as well as marketable skills. They will also be directly involved in dissemination of research results through conference presentations and journal publications. In addition to their fundamental interest, the microlasers also have numerous potential applications. The PI has a License Agreement with Nomadics, Inc., which is interested in developing commercial products based on the microlasers.
