Nonlinear volume holography is employed to realize arbitrary wave-front shaping during nonlinear processes with properly designed 2D optical superlattices. The concept of a nonlinear polarization wave in nonlinear volume holography is investigated. The holographic imaging of irregular patterns was performed using 2D LiTaO₃ crystals with fundamental wave propagating along the spontaneous polarization direction, and the results agree well with the theoretical predictions. This Letter not only extends the application area of optical superlattices, but also offers an efficient method for wave-front shaping technology.

Nonlinear photonic crystals have been employed as computer-generated holograms to manipulate the wavefront of the nonlinear waves. However, the disadvantages of the binaryfabricated structures gradually appear because of their adverse effects on the manipulation quality, especially in the field of nonlinear shaping and imaging. A generalized encoding method has been proposed for constructing nonlinear holographic processes of high quality, which is called a quasi-multivalueencoding method. Both theoretical and experimental results demonstrate that, compared with the conventional binary encoding method, this generalized encoding method is helpful to reduce the distortion and high-order diffraction effects. The integrated ability to convert the light frequency and to reshape its wavefront with a high resolution in any desired way can be very useful for all-optical shaping, switching, imaging, manipulating, and so on.