A New Class of Novel Nonlinear Optical Materials for Real-Time Quasi Phase-matched Second Harmonic Generation and Beam Steering Devices

Second-harmonic generation, electrooptic modulation and optical beam steering are among the most important applications of second-order nonlinear optical processes. A new concept in the design of novel nonlinear optical materials is proposed in which second order chromophores are incorporated in polymers with low glass transition temperatures (Tg). Quasi phase-matched second-harmonic generation in such materials can be realized by periodically poling the chromophores in the direction of the electric field; there is no SHG in the absence of the poling fields. Optical beam steering can also be realized due to the change in the refractive index of the film caused by the applied electric fields. The proposed polymers possess low glass transition temperatures that allow the small chromophore molecules to reorient under the presence of an applied electric field. The requirements for the active chromophore molecules include high hyperpolarizability, B, small size, and ease of processability. The large molecular hyperpolarizability provides higher second-order nonlinear optical responses when aligned in the direction of the poling electric field. The small size of the dopant molecules and the low glass transition temperature of the host medium will ensure facile reorientation of these molecules under the applied electric field, fast nonlinear optical response and large change in refractive index. The time scale for the response can be expected to be microseconds or faster.