Development and Characterization of an Optically Tunable Dielectric Material

The ever increasing use of wireless devices has caused a need for devices that can operate over a range of frequencies and conditions. This can be accomplished by using tunable circuits that utilize a tunable dielectric material. This work proposes a new optically tunable dielectric material that consists of a transparent polymer mixed with particles of cadmium sulfide, which are photoconductive.;A potential method to simulate the properties of a heterogeneous material is presented. The validity of the simulations were confirmed by comparing them to Bruggeman's effective medium theory and percolation theory.;The characterization apparatus developed in this work was used to measure the complex permittivity of the polymer-cadmium sulfide films. The shift in dielectric constant of the films with illumination was at least 9%. The dielectric loss tangent of the materials also increased by up to 0.085, from 0.063 to 0.148.;The optically tunable dielectric material shows a shift in dielectric constant that may make it comparable with ferroelectric materials. The opportunity exists to increase the change in the dielectric constant and decrease the change in the dielectric loss tangent with further optimization.;A resonant characterization apparatus was developed to measure the microwave properties of optically sensitive films deposited on glass cover slips. The apparatus was a modification of the characterization apparatus known as the split-post dielectric resonator.