Dynamic sub-wavelength encryption

Abstract

The suggested device includes a spatial light modulator (SLM) allowing varying the polarization state of an input illumination source. Attached to the SLM a sub wavelength grating is placed per each pixel of the device. This grating is used to encode the input information. The decoding is done by another sub wavelength grating. When the two gratings are attached a variation of the energetic efficiency between the two polarization states occurs. The polarization ratio encrypts the spatial information stream. The sub wavelength grating are hard to copy and thus high encryption capability is obtained.