Characterisation and process optimisation of photosensitive acrylates for polymeric optical waveguides

In this paper, we present our recent progress on the characterisation and process optimisation of photoresist-like fluorinated acrylate and cyclomer acrylate copolymers. Different acrylate formulations from cyclomer acrylates have been exploited and compared with fluorinated polymer from available sources. Both acrylates show negative thermooptic (TO) effect with temperature. The thermooptic coefficient, dn/dT of the polymers are as high as the order of 10^-3, which is comparable to those of available optical polymers. Higher values of dn/dT are shown by the fluorinated acrylate compared to that of the cyclomer acrylate type. Characterisation of prebaked and UV cured polymer samples had been analysed using FTIR. The time and intensity of UV curing were optimised to obtain waveguide channel of width between 40μm and 10μm for cyclomer whereas for fluorinated only the UV curing time has been optimised. The development techniques of these acrylates are also different; the cyclomer used the aqueous based developers while the fluorinated acrylate develops use the hydrocarbon solvent. Refractive indices of the cyclomer acrylates is between 1.52-1.53 while the fluorinated type is 1.521. Microstructural channel waveguide had also been analysed via scanning electron microscope (SEM) which shows the channel waveguide structures.