Second order nonlinearity of the material for recording hologram in the case when frequencies of object and reference waves are different

摘要

The transformation properties of dynamic hologram recorded in a quadratically nonlinear material are considered for the general case when the frequencies of object and reference waves are essentially different. The expressions are deduced that determined the wavelength of the reconstructed wave and directions of propagation of the rays of light that form the image. An experiment is carried out on the base of a noncollinear scheme of nonlinear interaction. A hologram was recorded in a KTP crystal by the light of a YAG:Nd laser (λ = 1.064 μm), the width of the pulses being 300 ps. The frequency of the object wave was shifted due to the Raman scattering in a crystal Ba(NO_3)_2 The values of the frequency shifts were Δv, 2Δv, 3Δv (Δv = 1047 cm~(-1)). Each of the shifted in frequency component formed an image of the object whose resolution was close to the diffraction limit. All these components were separated in space. The value of separation was in a good agreement with the predictions of the theory. It was stressed that the inertialess nature of a hologram of such a type makes it possible to use them for ultrafast communication of signals in optical communication lines.