Materials Science & Biophysics Research Seminar Series

Spring 2021 Seminar Series

The materials science and engineering of high-power lasers

John Ballato, PhD
Professor of materials science and engineering at Clemson University
J. E. Sirrine Endowed Chair in Optical Fiber

Friday, February 5, 2021
1:00 - 2:00 p.m.
Virtual seminar -Join on MS Teams

Continued progress in the development of optical fiber-based lasers has led to the present state where further improvements in performance are limited by intrinsic optical nonlinearities. In order to manage such limitations, laser designers have largely adopted the approach of microstructuring the fiber to shift nonlinear thresholds to high optical powers. The nonlinearities are accepted as fixed and performance is enhanced through fiber geometric complexity. This talk treats a different option, which is to mitigate optical nonlinearities at their fundamental origin: the materials with which the light interacts. This work provides a road-map for the development of simple core/clad optical fibers whose enhanced performance – in particular, marked reductions in optical nonlinearities – is achieved materially and not through the more conventional present routes of geometrically complex fiber design. More specifically, the material properties that give rise to Brillouin, Raman, and Rayleigh scattering, transverse mode instabilities (TMI), and n2-mediated nonlinear effects are compiled and results on a wide range of optical fibers are discussed with a focus on trends in performance with glass composition. Further, optical power scaling estimations as well as binary and ternary property diagrams associated with Rayleigh scattering, the Brillouin gain coefficient (BGC) and the thermo-optic coefficient (dn/dT) are developed and employed to graphically represent general trends with composition along with compositional targets for a single intrinsically low nonlinearity, silica-based optical fiber that can achieve the power-scaling goals of future high energy fiber laser applications.