Optical cryptosystem based on single-pixel encoding using the modified Gerchberg-Saxton algorithm with a cascaded structure.

In this paper, an optical cryptosystem is developed based on single-pixel encoding using the modified Gerchberg-Saxton algorithm with a cascaded structure. A series of random intensity-only patterns are pre-generated as principal security keys, and phase-only masks for optical encoding and decoding are generated by the modified Gerchberg-Saxton algorithm with a cascaded structure. Subsequently, a series of 1D intensity points, i.e., ciphertexts, are recorded by a single-pixel detector, which may provide a potential for establishing low-cost and compact security systems. The phase-mask generation process can be flexibly designed by modifying the Gerchberg-Saxton algorithm with a cascaded structure; hence high sensitivity and the large indirect space for phase can be guaranteed. It is also illustrated that compared with previous works, the higher eavesdropping percentage is requested to the attackers in the proposed single-pixel optical cryptosystem. The proposed method using a cascaded structure provides a novel strategy for single-pixel intensity-modulated optical security.