Photorefractive speckle pattern amplification

MYRIAN TEBALDI; LUIS ARIZMENDI; NESTOR BOLOGNINI

Porlamar (Venezuela)

Congreso; 5th Iberoamerican meeting on Optics and 8th Latin American Meeting on Optics, Lasers and their Applications; 2004

Comité Venezolano de Óptica

Photorefractive crystals make possible an efficient energy transfer from the pump beam (reference) into the signal beam. The coupling of interacting beams in dynamic hologram recording in photorefractive media can be utilized to produce an image amplication whose action is based on a light–induced change of the refractive index. A speckle distribution is characterized by a randomly varying intensity and phase. In our case, we consider a speckle distribution and a plane wave as the interfering beams inside a BSO crystal. The incident beam ratio of the two interfering beam depends on the speckle beam intensities and an statistical distribution of the beam ratio appears in the crystal. Under this condition, the speckle amplification is analyzed. When the reference beam is phase shifted, a local amplification is observed in the reconstructed speckle beam. The amplification is studied in terms of the input mean intensity of the speckle beam, the pupil aperture diameter of the imaging lens and the external applied voltage.