All-optical encrypted movie based on fractional Fourier transform

With fast developments of communications and internets,movies containing huge information are widely used.An optical encryption/decryption method based on fractional Fourier transform is proposed.The method increases number of the encryption keys for an all-optical encrypted movie from two to four.The security level of the all-optical encrypted movie is enhanced greatly.The interaction site of the amplitude sinusoidal grating is optmized.Encryption and decryption are needed once for a whole movie in the proposed method rather than for every frame of the movie in the previous methods.The implementation of the method is significantly simplified.The effectiveness of the method is verified with simulations.