Organic polymer films for second order nonlinear optical applications

Discusses polymers exhibiting second order nonlinear optical (NLO) phenomena, such as the linear electro-optic effect, whereby the refractive index varies linearly with an applied electric field, and second harmonic generation (SHG), where light of frequency ω is converted to light of frequency 2 ω. In order for a polymer to exhibit these effects, its constituent molecules must, in part, possess a finite molecular nonlinearity, and these NLO molecules must be arranged non-centrosymmetrically so that their individual effects do not cancel. The linear electro-optic effect is the main topic of the paper, with its application as a fast response modulator, whereby information to be transmitted is applied to the polymer as an electric field. If light is passing through the NLO polymer then the electric field alters the refractive index of the polymer such that the emergent light is modulated synchronously with the electric field. Thus, information can be converted between electrical and optical media. As electro-optic modulators NLO polymers offer exciting prospects with predicted electro-optic efficiencies at least an order of magnitude higher than present inorganic devices