Secure data transmission over specialized fiber-optic link

In this article we present an alternative method of secure data transmission over physical layer for the “first/last mile” segment of intra-corporate network implemented with specialized fiber-optic link. Proposed solution is based on using few-mode optical fibers with specific refractive index profile as an “encryptor”, which creates unique distortions in accordance with its unique differential mode delay. Therefore, transmitted traffic becomes strongly distorted and cannot be processed without corresponding “decryptor” which might be either another optical fiber with “inversed” refractive index profile in relation to the “encryptor”-fiber or electronic dispersion compensator device modified for such an application. We also propose to utilize elements of mode division multiplexing technique as an additional protection for secure data channel. Such an approach is based on using only one particular mode (or modes) for secure data transmission, which is changed with certain time interval according to the privacy key. This work presents configurations of proposed “crypto-fiber-optic” link as well as the list of problems which require a solution for designing, developing and implementing the presented approach.