Active formation of an antiguide structure in a photorefractive polymer for enhanced second-harmonic generation

An antiguide structure for enhanced second-harmonic generation was actively constructed in a photorefractive polymer by use of a pump beam. Irradiation of a pump beam enhanced second-harmonic power, and blocking the pump returned the power to the initial value. The electric-field dependence of the degree of enhancement of the second-harmonic power confirmed that the antiguide structure was constructed through a photorefractive-index change in the medium. The photorefractive-index change accompanied molecular reorientation induced by the pump-generated space charges. The thermo-optic effect on formation of the structure is also discussed.