Helium ion implanted waveguide lasers

High energy ion implantation may be used to modify the refractive index of surfaces of insulators to form optical waveguides and waveguide lasers. Bombardment with MeV helium ions normally reduces the crystalline indices at the end of the ion range. This low index region provides an optical barrier and so defines a waveguide. The method has been demonstrated in more than 30 crystalline targets. Possible factors which influence the refractive index profile are discussed. A successful approach to form waveguide lasers is to use the implantation damage method to construct a waveguide in a predoped crystal. After annealing the optical losses are reduced and planar waveguide lasers have so far been demonstrated in Nd doped YAG, YAP, LiNbO3, Gd3Ga5O12 and Bi4Ge3O12. (orig.)