Crystal engineering of oxyfluoride glass with increased crystallinity and transmittance towards enhanced luminescence

Glass ceramic (GC) is a promising optical gain material for fiber laser applications. However, the greatest challenge for GC is the conflict between high crystallinity and significant optical loss produced by crystals scattering. Herein, we propose a simple method based on crystal engineering of glass to enhance the crystallinity and transmittance. On the basis of this approach, the crystallinity, transparency and luminescence efficiency of the GC samples are all enhanced dramatically. In addition, owing to the depletion of Y3+ ions in the glass matrix during the precipitation of KYF4 crystals, the refractive index differences between the glass matrix and the crystals are significantly diminished, which results in suppressed light scattering towards higher crystallinity (-72%) and transmittance (-88% at 900 nm). These excellent performances of GC show that crystal engineering of glass not only presents a way to overcome the conflict between crystallinity and transmittance, but also offers significant potential for the fabrication of optical composites with multiple functions.