Abstract

One-dimensional (1D) and two-dimensional periodic structures optically induced within photorefractive crystals suggest excellent tools to study the interactions of wave packets with nonlinear periodic systems^1,2 In this work, we experimentally investigate the linear and nonlinear discrete diffraction of light beams within one-dimensional optically induced modulated photonic lattices (MPL) in bulk photorefractive samples of lithium niobate (LiNbO₃). The lattices are fonned in LiNbO₃:Fe and LiNbO₃:Cu samples using two-beam coupling scheme for recording of photorefractive gratings. Ordinarily polarized irradiation either of He-Ne laser w ith λ=633 nm or YVO₄:Nd³⁺ laser with λ=532 nm form within the samples interference patterns with wave vectors parallel to the crystal optical axis. The photorefractive grating with spatial period Λ₁ from 10 to 15 μm is fonned at the first step with its following modulation by second grating with Λ₂=MΛ₁ where m is integer (m=2.5 in our experiments). The recording interference patterns are partially overlap within the crystal to fonn in different areas as MPL as single-period gratings with periods Λ₁ and Λ₂.

© 2007 IEEE