Second harmonic generation from RE doped BGO waveguides

Samples of EGO doped with Tm3+, Er3+, Ho3+, EU3+, Sm3+ and Nd3+ have been implanted at LNT (77 K) with Hei ions for waveguide fabrication. The energy and the dose of the implantation are 2 MeV and 5 x 10(16) ions/cm(3), respectively. The samples have been annealed in the furnace at 250 degrees C, 350 degrees C, 400 degrees C and 350 degrees C for 1 h in air. The SHG intensity improved with increasing annealing temperature, due to removal of defects caused by the implantation. There is a restructuring of the implanted guide which results in a modified crystal lattice and a greatly improved SHG. The effect increases with the difference between the radius of the RE ions and the Bi ion. The latter effect could be explained by the mismatch of ion size of the RE ion which distorts the cubic structure of EGO in the implanted region to become slightly anisotropic, which in turn improves the SHG of BGO:RE waveguide layer. (C) 2000 Elsevier Science B.V. All rights reserved.