By introducing sinusoidal chirping into a periodic nonlinear optical susceptibility, we propose that the Čerenkov radiative second-harmonic generation is greatly enhanced in theoretical calculations, and this is demonstrated with an organic copolymer. The use of nonlinear optical chirping with an average χ(2) period of 20 μm, a modulation period 200 μm (modulation index ≃9), and a total length of 2 mm with the VDCN/VAc copolymer film yields enhanced second-harmonic generation by a factor of ~7. This enhancement is much greater than that with a uniform periodic χ(2) film with a period of 60 μm, which is consistent with the theoretical estimates.
© 1994 Optical Society of America
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