Reconfiguring Computer-Generated Holographic Coding Patterns to Enhance Optical Access Network Security

Abstract

In this paper, spatial light modulators (SLMs) are devised as a reconfigurable optical coding access device with computer-generated hologram (CGH) coding patterns scrambled over them for secure optical data communications. SLM is composed of many pixels arranged in an array which can be controlled by electrically triggered pulses to generate different coding patterns. By using SLMs we can modulate users’ data signal with different CGH pattern array to prevent from deciphering of eavesdropper. According to the transmitted holographic information from transmitter encoder to receiver decoder, symmetrical balanced decoders can be configured (and reconfigured) to recover coded data bit of each network user by correlating the received combined hologram patterns with the desired CGH pattern over photo-detector. In the proposed system, each user encodes the transmitted data bit with signature maximal-length sequence (M-sequence) code which are further mapped onto a CGH coding pattern. Due to the pseudo-orthogonal and reconfigurable characteristics of M-sequence codes, eavesdropper will suffer more difficulty in deciphering received data signal. On system analyses, as competing with arrayed-waveguide gratings (AWGs) devices, we conclude that the approach of CGH pattern array can largely improve network security performance for its characteristic advantages of larger capacity, more flexibility, higher confidentiality and easier implementation.