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The work presented in this thesis describes an investigation into the properties and behaviour of nonlinear optical guest molecules doped into polymeric matrices. The interactions of the guest molecule 2-(N, N dimethylamino)-5-nitroacetanilide (DAN) with a polycarbonate and polymethyl methacrylate (PMMA) host are compared. A detailed characterisation of the two systems is described employing infra red spectroscopy and analysis of the chromophore alignment during electric field poling. The study reveals that hydrogen bond formation between the guest and the polar polycarbonate backbone accounts for the unusually good alignment stability previously reported in the polycarbonate system. The molecular hyperpolarisibility of DAN in PMMA is also measured and the apparent enhancement compared with solution measurements is accounted for by the more polar nature of the polymer environment. A new technique allowing the measurement of the dipole moment of polar molecules doped into thin polymer films is also presented. The technique is demonstrated on a series of zwitterionic chromophores whose measured dipole moments range from 30 to 40 D. Electrochroism measurements are performed to account for aggregation of the monomer species which then permits the first hyperpolarisibility of the molecules to be calculated. The values of dipole moment and hyperpolarisibility are found to be very sensitive to the choice of dielectric cavity shape used when deriving the local field correction factors. The measured values are therefore compared with theoretical calculations and a preferred cavity shape is proposed.

This dissertation presents the novel creation of a hybrid D-fiber electro-optic polymer electric field sensor. The sensor is made by removing a portion of the cladding from a D-shaped optical fiber, thus exposing the core to interaction with external stimulus. Then, an electro-optic polymer is deposited, partially replacing the core of the fiber. Next, the polymer is poled to endow it with electro-optic properties. This sensor is packaged in order to restore its mechanical strength. Because D-fiber is not intrinsically compatible with standard optical equipment it is fusion spliced to standard polarization maintaining fiber. Finally the sensor is tested for electro-optic sensitivity. The hybrid D-fiber electric field sensors designed and fabricated in this work meet the requirements of mechanical strength, temporal stability, minimal perturbation of the electric field by the sensor, and a small and flexible cross-sectional area so that it can be embedded into the device under test. A fully packaged hybrid electro-optic polymer D-fiber electric field sensor which is capable of detecting electric fields of 50 V/m at a frequency of 6 GHz is produced. The sensor's electro-optic response is shown to be temporally stable. Additionally, the sensor is physically robust, and physically and electrically non-intrusive. This work also adds a thorough understanding of the design and fabrication of D-fiber waveguides with a polymer material deposited in the core. Several new fabrication techniques are developed and presented. A path to greater electric field sensitivity is outlined for future research.