Photorefractive Phase Mask And Phase Components

Using optical imaging method, we successfully fabricate photorefractive phase mask and photorefractive phase components (such as phase zone plate, phase Dammann grating, lens array, (1+1)-dimensional, (2+1) -dimensional, circle and ring waveguides and so on) for the first time, in LiNbO3:Fe crystal by photorefractive effect. Using the photorefractive saturable nonlinearity, we fabricate both types of step and gradient photorefractive phase components through the ways of digital recording and analog recording under different ratio of light intensity respectively. To overcome the influence of the anisotropy of photorefractive nonlinearity on fabricating two-dimensional phase components, and to raise the diffraction efficiency of the quantized phase zone plate, we deduce theoretically and select experimentally optimal experimental conditions. We show that writing conditions can be controlled by the irradiation of the incoherent background light.We observed that the photorefractive phase mask is visible, and explain it using the principle of waveguide for the first time. If we use the photorefractive phase mask that replaces the amplitude mask as the input mask in optical information processing, the energy loss can be large reduced, and we can get higher conversion efficiency. If we use it in optical correlator, we can get much sharper correlation peak.Our method has the advantages of real-time, simple, low cost and the crystal can be used circularly. It advances a new way for fabricating binary optical components and integrated Optical components using traditional method. It is a new optical engineering of variable refractive index using all optical method ?the spatial distribution of the refractive index in crystal is changed directly by the spatial distribution of the input light intensity through nonlinear optical effect.