Optical Correlators for Cryptosystems and Image Recognition: A Review

Abstract

Optical correlators are efficient optical systems that have gained a wide range of applications both in image recognition and encryption, due to their special properties that benefit from the optoelectronic setup instead of an all-electronic one. This paper presents, to the best of our knowledge, the most extensive review of optical correlators to date. The main types are overviewed, together with their most frequent applications in the newest contributions, ranging from security uses in cryptosystems, to medical and space applications, femtosecond pulse detection and various other image recognition proposals. The paper also includes a comparison between various optical correlators developed recently, highlighting their advantages and weaknesses, to gain a better perspective towards finding the best solutions in any specific domain where these devices might prove highly efficient and useful.

Optimizing Tunable LC Devices with Twisted Light

“…Regarding their structure, NDLCDs can be roughly classified into two broad groups: those with a large number of pixels (>10 5 ) with constant shape, distributed in a regular matrix, usually driven by active-matrix electronics, and those with a moderate number of pixels (say, <10 3 ) with arbitrary shape, usually driven by external drivers on passive matrices.…”

“…SLMs have found plenty of applications [2]. OASLMs can be used for real-time object recognition by optical correlation [3], whereas EASLMs are employed in a plethora of dissimilar systems. To name a few, optical switching [4] and wavelength-selective switches (WSSs) [5] are key in optical communications, while computer-generated holography [6], adaptive optics [7], optical Fourier neural schemes [8], and optical computing [9] are applied to many fields, including hot topics like artificial intelligence [10].…”