Abstract

Gain enhancement via signal beam chopping for two-wave coupling with a Bi₁₂SiO₂₀ crystal is demonstrated. In this method the gain of a two-wave coupling scheme is increased using a transient effect. This effect is created during the grating formation due to the phase difference between the interference fringe of the light intensity incident on the crystal and the photoinduced refractive index fringe in the crystal. The maximum gain of 11.7 was achieved with an applied electric field of 6.0 kV/cm, a fringe spacing of 29.5 μm, a beam intensity ratio of 1240, and a chopping frequency of 6.0 Hz. This gain is nearly as high as that obtained with the moving interference-fringe method proposed by Huignard and Marrakchi. The gain enhancement using the transient effect caused by the polarization rotation of the signal beam (using a rotating halfwave plate) is also described. Preliminary experimental results are shown.

© 1991 Optical Society of America

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