Fabrication and characterisation of waveguide and grating structures induced by ultraviolet radiation in polymers with a shortened writing process

摘要

Optical components based on waveguides and gratings are in use in several areas of optical communication and sensor technology. Such structures are realized in both inorganic and organic materials with different more or less complex fabrication methods. The inscription of optical structures induced by deep ultra violet (DUV) radiation in homogeneous polymer substrates is a relatively simple lithographic one step process in comparison to other established fabrication methods. For this technology the irradiation process was enhanced whereby the writing time was shortened. The writing time to achieve a refractive index change in the order of magnitude of 10~(-3) is now in the range of a few minutes. Various polymers were investigated and their suitability for waveguide applications was compared. Some of the polymethylmethacrylate (PMMA) based copolymers have a relatively high glass transition temperature (T_g) of over 140°C. These optical polymers have the potential to be applied at higher temperatures than commercial PMMA based polymers. The modification zone was characterised by several methods. The main points of the work were the determination of the refractive index and the optical loss of the waveguides. Grating structures were generated by the phase mask method. The optical functionality of these gratings is described.