Optical waveguides fabricated by ion implantation of Si(+) and N(+) in SiO(2): a Raman investigation

We report an investigation of optical waveguides that are fabricated by successive ion implantations at different energies of Si(+) or N(+) ions into SiO(2) thermally grown on (100) Si substrates. Implantations of both the species result in optical waveguides that sustain propagation over the 5-cm length of the sample. Loss coefficients for the waveguides are measured by using Raman spectroscopy and are compared with the values obtained in the usual manner by collecting elastically scattered light. A typical loss determined by the Raman technique was 3.2 dB/cm for the Si-implanted waveguide. Raman data that are obtained in the waveguided configuration show a contribution to loss from luminescence. The luminescence signal is found to be modulated by an interference between the directly scattered radiation from the waveguide region and that reflected from the Si-SiO(2) interface. Rapid thermal annealing is found to reduce the intensity of the luminescence and thus lower the value of the loss coefficient. The lowest loss obtained for the Si-implanted samples is 2.7 dB/cm and 3 dB/cm for the N(+)-implanted sample.