Patent ID: 7542186

Claim:
A method of 3D holographic recording comprising: dividing a femto-second laser pulse into a plurality of light beams; focusing the divided plurality of light beams in a parallel direction; selecting four light beams of the plurality of light beams focused in the parallel direction; controlling each optical phase of the selected four light beams; and focusing the selected four light beams into a photosensitive material capable of multi-photon exposure so that the photosensitive material is exposed to interference among the four light beams and multi-photon absorption in the photosensitive material is induced, thus recording a 3D phase hologram on the irradiated portion in the photosensitive material, wherein the photosensitive material capable of multi-photon exposure is glass that undergoes photo/thermo-induced refractive index change, and wherein the glass that undergoes photo/thermo-induced refractive index change is glass having a composition close to 15Na 2 O-5ZnO-4Al 2 O 3 -70SiO 2 -5NaF-0.01Ag 2 O-0.01CeO 2 .