| Abstrakt: |
Highly birefringent liquid crystals are attractive for photorefractive applications but device operation, usually restricted to the Raman-Nath regime, can be degraded by small phase shifts between the optical and refractive index gratings and coarse grating spacings with narrow beam intersection angles. Having to apply external electric fields and tilt the cell at an angle to the grating k vector cause further complications. In this letter, two-beam coupling in a hybrid photorefractive cell comprising a nematic liquid crystal layer influenced by an Fe doped KNbO3 window is described. The KNbO3 window determines photorefractive properties while the liquid crystal amplifies the overall refractive index modulation. Full Bragg matched gain and large beam intersection angles, with perfect 90° phase shifts between the optical and refractive index gratings, at normal incidence, without the need for an external field are demonstrated. [ABSTRACT FROM AUTHOR] |
