Citation:Ward, J. M., Wu, Y., Khalfi, K., Nic Chormaic, S., 2010. Short vertical tube furnace for the fabrication of doped glass microsphere lasers. Review of Scientific Instruments, 81(7), pp. 073106-1-073106-4
We report on the design of an electric tube furnace that can be used for the fabrication of doped glass microsphere lasers. The tube furnace has a short hot zone of length 133 mm and is based on a quartz tube design. Doped laser glass particles, specifically Er:Yb phosphate glass (IOG-2), of ∼ 1 μm diameter are blown into the furnace using a 60 ml syringe and microspheres ranging in size from 10 to 400 μm are collected at the output of the tube furnace in a Petri dish. The furnace operates at a wall temperature of ∼ 900 °C and is capable of making microspheres from glasses with glass transition temperatures of at least 375 °C. High quality (Q ∼ 10^5) whispering gallery modes have been excited within the microspheres by optically pumping at 978 nm via a tapered optical fiber.