| In the last decade, there has been increasing interest in room temperature (or thermally) vulcanizing (RTV) silicone rubber and particularly in PDMS. Its main applications have been in chemical and mechanical engineering, in soft lithography and in microfiuidics. Applications in photonics have started to build-up, although these are not as strong as in the other domains. This material represents an enormous potential for the design of phase masks and photonic crystals for applications in Bragg gratings and in microfabrication as a tunable dynamic template for the reproduction of photonic microstructures.;A simple PDMS phase-mask is cast onto a photosensitive fibre and high quality Bragg gratings are written directly through them for the first time. Material limitations do hinder the use of these masks under some conditions for direct writing of Bragg gratings. However, these stretch tunable elastomeric phase-masks are also valuable as period-tunable templates that may be used in conjunction with more robust, UV transparent resins.;A duplicating technique is presented in detail to form defect-free structures of a silica holographic phase-mask with feature sizes of around 500 nm into a PDMS microstructure. A non-destructive technique of PDMS surface modification is developed using a C4F8 RIE plasma. With this alteration, a method to duplicate the surface of a PDMS phase-mask template is demonstrated, under stretch or relaxed states, into other identical PDMS phase-masks. By using a thickness profile, it is possible to fabricate a phase-mask with a complex non-linear period chirp whilst it is inconceivable to do so using equivalent methods in a silica phase-mask. These unique phase-masks will allow the simple fabrication of complex Bragg gratings.;Finally, 2D and 3D periodic microstructures in PDMS are demonstrated by a unique method, and a new technique is proposed for the first time to build inverse opals with an integrated waveguide in a PDMS matrix.;In the first, part of this Masters thesis, extensive research on the mechanical, chemical, thermal and optical properties of PDMS and many experimental confirmations are presented. The behavior of PDMS under UV radiation because its application is in writing Bragg gratings, requires an in-depth knowledge of the material properties in the particular wavelength of interest and this is studied experimentally. Among other things, a refractive index of 1,444 for the PDMS at 266 nm was measured and it was discovered that the material is transformed in two steps under UV exposure. This transformation depends on the intensity of the beam and the thickness of the material but it is independent of the peak power or repetition rate of the laser, as well as the curing conditions. |
