In this paper, the formation of novel Si/SiO 2 multilayer structures using separation by implantation of oxygen (SIMOX) technology is reported. The structures were formed to investigate the suitability of SIMOX technology for the formation of Si waveguiding structures. The method comprised two subsequent oxygen implants at 9 and 3.8 MeV and a final high temperature annealing step at 1300ЊC for 12 h. Fourier transform infrared reflection spectroscopy, Rutherford backscattering spectroscopy/channelling analysis, cross-sectional transmission electron microscopy, and spreading resistance profiling have been used to characterize the samples. Additionally, waveguiding loss measurements have been carried out. Interaction or transport of oxygen between the two buried oxide layers is not observed after the anneal and so, it is concluded that the implantation and annealing schedule followed here can be safely used for the production of such multilayer structures. It is shown that for 3.8 MeV O ϩ implantation into Si, a dose of 1 ϫ 10 18 cm Ϫ2 is adequate to form a continuous, highly resistive, buried layer, while for the 9 MeV case, a higher dose is necessary. Both Si layers qualify as waveguiding layers for infrared wavelengths (1.523 m), as they are of high crystal quality. Waveguiding loss measurements give a high value of 20 dB/cm, indicating that the process needs further optimization.