Patent ID: 8063463

Claim:
A method for encoding information that is encoded in spatial variations of the intensity of light characterized by a first wavelength in light characterized by a second wavelength, the method comprising: transmitting the first wavelength light through a photo-conducting material in which electron-hole pairs are generated by absorbing photons from the first wavelength light to generate a first density distribution of electrons homologous with the spatial variations in intensity of the first wavelength light; trapping electrons from the first electron density distributions in a trapping region to generate an electric field homologous with the density distribution in a modulating material that modulates a characteristic of light that passes therethrough responsive to an electric field therein; transmitting a pulse of second wavelength light having sufficient energy to generate electron-hole pairs in the photo-conducting material through the modulating material and thereafter through the photo-conducting layer to generate a second additional electron density homologous with the first electron density distribution; and trapping electrons from the second electron density distribution in the trapping region; where the transmitting the pulse of second wavelength light through the modulating material modulates the pulse of second wavelength light in response to the electric field and encodes the pulse of second wavelength light with the information.