A Novel Route to Fibers with Incongruent and Volatile Crystalline Semiconductor Cores: GaAs
Thomasina Zaengle, Ursula J. Gibson, Thomas W. Hawkins, Colin D. McMillen, Basanta Ghimire, Apparao M. Rao, John Ballato
Abstract
A novel extension to the molten core method was employed to realize a glass-clad, crystalline gallium arsenide (GaAs) core fiber for the first time to the author's knowledge. GaAs is of considerable interest for its optoelectronic and nonlinear properties, but decomposition and volatility, usually leading to incongruent solidification, normally preclude melt-processing under ambient conditions into an optical fiber. Presented here are results on tin as a flux to melt GaAs at a temperature where volatility is negligible, permitting the thermal drawing of long lengths (100 m) of glass-clad, crystalline GaAs-containing fibers. Laser annealing is employed to segregate the Sn and GaAs phases, both across and along the fiber. This work presents an important new tool for scalable fabrication of glass-clad crystalline core materials previously thought incompatible with molten core processes and opens the door to a wide range of novel and useful in-fiber optoelectronic devices.