Enhancement of Čerenkovian second-harmonic-generation power with ultraviolet irradiation-formed nonlinear optical χ (2) corrugation and channel waveguide

By irradiation of a UV source through a metallic mask with a chirped periodic or periodic structure and a metallic wire onto vinylidene cyanide/vinyl acetate copolymer, the Cerenkov-radiative second-harmonic generation has been efficiently enhanced, with the channel waveguide having a chirped periodic nonlinear optical susceptibility χ(2) corrugation. By use of an ArF 193-nm laser close to an inherent absorption line of the copolymer as the UV source, not only a nonlinear optical χ(2) corrugation with the average period Λs0= 20 μm and a chirping index ϕm≃9 but also a channel guide 60 μm wide were induced. The enhancement factor of the Cerenkovian second-harmonic-generation power achieved was 7.4 times that of a uniform nonlinear optical χ(2) scheme. This simple UV irradiation method leads to almost the same effect as is obtained by a contact electrode method, showing its feasibility for the Cerenkovian second-harmonic-generation scheme.