Organic electro-optics: Understanding material structure/function relationships and device fabrication issues

Abstract

Realization of large electro-optic (EO) activity for dipolar organic chromophore-containing materials requires the simultaneous optimization of chromophore first hyperpolarizability (β), acentric order <cos³θ>, and number density (N). As these parameters are inter-related, correlated quantum and statistical mechanical calculations are required to understand the dependence of macroscopic electro-optic activity upon chromophore structure and intermolecular electrostatic interactions. Correlated time-dependent density functional theory (TD-DFT) and pseudo-atomistic Monte Carlo (PAMC) calculations are used in an attempt to understand the dependence of linear and nonlinear optical properties on dielectric permittivity, optical frequency, and a variety of spatially-anisotropic interactions that can be nano-engineered into the macroscopic material structure. Structure/function relationships are considered for three classes of organic electro-optic materials: (1) Chromophore/polymer composite materials; (2) chromophores covalently incorporated into passive organic host materials; (3) chromophores incorporated into chromophore-containing host materials—a new class of materials referred to as binary chromophore organic glasses (BCOGs). Issues associated with processing these materials into device structures, including those relevant to the integration with silicon photonics, are discussed. The purpose of this article is to address issues critical to ascertaining the viability of organic electro-optic (OEO) materials for next generation telecommunications, computing, and sensing applications.