THERMO-OPTIC COEFFICIENT OF DIFFERENT PHOTOSENSITIVE ACRYLATE POLYMERS FOR OPTICAL APPLICATION

Abstract

Thermo-optic (TO) effect in materials can be exploited in the fabrication of optical devices such as optical switches and couplers. These optical devices play a key function in communication networks because by changing the temperature they have control over the optical path. Recently, polymer materials have begun to receive attention for the application of the TO switch in integrated optics. The polymers exploited for the variation of refractive index with temperature in our work involve the use of cyclomer acrylate, which is compared to the fluorinated acrylate available in the market. We focus the on cyclomer acrylate resin potential to be employed in fabricating optical devices especially the optical waveguide and optical switch. Formerly, this polymer is used as an adhesive and coating only. Different acrylate formulations from cyclomer acrylates have been exploited. Both acrylates show negative TO effects with temperature i.e. decrease of refractive index result in the increase in temperature. This is expected as the refractive index of the polymers are reduced, as density typically decreases with increasing temperature. This is in accordance to the dependence of polarizability and density of a particular material, to its refractive index. For both types of polymers, the change of the refractive index as a function of temperature is linear. The slope can give the dn/dT of the film. The dn/dT of polymers are as high as the order of 10-4, which is comparable to those of optical polymers. Higher values are shown by the cyclomer acrylate compared to the fluorinated type.