OPTICAL WAVE-GUIDES IN POLYMERIC MATERIAL BY ION-IMPLANTATION

Poly(methyl-methacrylate) (PMMA) substrates were implanted with He+ ions of energies between 50 keV and 250 keV and at 1 MeV and 2 MeV. The ion dose was varied between 10(12) and 10(15) ions cm-2. We measured the increase in refractive index of the implanted surface layer, which acts as an optical waveguide, by measuring the effective index of refraction n(eff) for different optical modes. According to the range of ions in the polymer, surface waveguides and buried waveguides could be generated. We found that the number of modes which a waveguide can carry depends on the ion dose. To obtain single-mode waveguides, low ion doses were used. Waveguides with optical losses below 1 dB cm-1 were found. The chemical effect induced by ion implantation was measured by IR spectroscopy and residual gas analysis, physical modification of the surface was studied by scanning electron microscopy. The refractive index profiles are discussed using simulation calculations.