Growth of single-crystal sapphire-clad ruby fibers

Abstract

Single‐crystal Cr‐doped Al₂O₃ fibers can be grown by a floating‐zone technique from small source rods locally melted at the end by a CO₂ laser. By using the same laser to melt and regrow only the surface of the fiber, the Cr concentration in this surface layer can be reduced by a factor of 100 or more by selective evaporation.