ABSTRACT
We have demonstrated experimentally the simultaneous self-conjugation of extraordinarily and ordinarily polarized light waves (lambda=514 nm), with the polarization state preserved, in a Ce:BaTiO(3) crystal. Conjugate o waves originate from coupling between o and e waves by means of a circular photogalvanic effect. The conjugator also takes advantage of the Ce:BaTiO(3) crystal, for which it is easy to generate an extraordinary conjugate beam by photorefractive backscattering. This beam of light is necessary for double phase conjugation.
ABSTRACT
We demonstrate that recording thick holographic phase gratings in photorefractive polymers can lead not only to very efficient Bragg diffraction but also to rather strong diffraction into non-Bragg orders. We show that this effect has features drastically different from those of Raman-Nath diffraction on thin gratings. We compare the experimental results with a model based on the theory of dynamic self-diffraction in a photorefractive medium. Applications of this effect in devices for optical image processing are proposed.
ABSTRACT
We have predicted and observed an anisotropic photocurrent induced in the cubic crystal Bi(12)SiO(20) by a high-contrast interference pattern. The transverse current detected when the interference pattern is tilted is caused by deflection of the direct current generated by an external voltage applied to the crystal.
ABSTRACT
The scattering cone (~2 degrees ) from an Ar laser beam (514 nm) in photorefractive KNbO(3):Fe has been observed to transform into a reconfigurable hexagonal spot array. This phenomenon can be explained through the creation of laser-induced transmission and reflection grating arrays.
ABSTRACT
It is generally assumed that lenslet arrays are needed to concentrate image light upon the relatively sparse detector areas in a focal-plane array. These have severe field-of-view difficulties and require considerable space to implement. We show how to manufacture optically parallel arrays of concentrators of controllable size and field of view with photorefractive crystals.
ABSTRACT
We present the theory for photorefractive two-beam coupling without optical activity in cubic crystals rotated around the [110] axis. We also describe two-beam coupling experiments in InP:Fe that fit the theory closely. The 15.5% gain enhancement for grating wave vectors aligned along the <111> directions is demonstrated explicitly.
ABSTRACT
Optical-activity-supported energy transfer is explained, and a transfer of 4% is observed in bismuth silicon oxide with same-frequency equal-intensity beams having the same circular polarization. The direction of energy exchange can be controlled by the sign of the electric field or the sense of the circularity. In general, energy exchange occurs by destructive and constructive interference between diffracted and transmitted beams; here, with the induced grating vector along the [110] direction, interference cannot occur unless optical activity and an external electric field are present.
