Abstract

Recently we showed that rare earth doped nano-crystalline glass-ceramic fibers could be lased with efficiencies comparable to that obtained in glass fibers¹ despite the presence of crystals embedded within the core of the optical fiber. This performance can only be achieved when the crystal size is kept small (usually of the order ~10 nm) keeping the scattering losses (at least in the IR) to a minimum. However, the benefit obtained by incorporating rare earth ions into a crystal environment (as compared with a glass) does not warrant the complexity of using a glass-ceramic fiber. More recently the properties of transition metal duped glass-ceramic fibers have been investigated and we reported a Cr⁴⁺-doped forsterite nano-crystalline fiber at CLEO 2001.² In this case the dramatic improvement in the spectroscopic properties obtained by using a nano-crystalline environment for the active ion is clearly worth the trouble of using a glass-ceramic fiber. This, coupled with the improved formability of a glass-ceramic over a single crystal host, is the driving force behind the work presented here.

© 2002 Optical Society of America