Title

Photonic Security System Using Spatial Codes And Remote Coded Coherent Optical Communications

Authors

Authors

N. A. Riza; M. M. K. Howlader;N. Madamopoulos

Comments

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Abbreviated Journal Title

Opt. Eng.

Keywords

optical security; optical code; identification card; security system; photonic encoder; coherent optical communications; keycodes; Optics

Abstract

A novel photonic security system is described using 2-D spatial codes based on both optical phase and amplitude information. This security system consists of an optical interferometric encoding subsystem that rapidly reads and encodes the 2-D complex-valued spatial code, forming a wideband frequency modulated optical beam and a colinear optical reference beam. After appropriate coherence coding of this beam pair, the light is launched into a low probability of intercept communication channel such as an optical fiber or a narrow beamwidth free-space optical link. At the remote code receiving and data processing site, the received light beam pair is first coherently decoded. Then, a high speed photodetector via optical heterodyne detection generates an encoded wideband radio frequency signal that contains the original 2-D code. Decoding is implemented in parallel via two independent systems. One decoder uses a Fourier transforming lens to reconstruct an electronic image interferogram of the complex-valued user code. This image interferogram is sent to a high speed electronic image processor for verification purposes. The other decoder is a high speed coherent acousto-optic time integrating correlator that optically determines match-mismatch between the received encoded signal and the code signal generated by the electronic database. Improved security to the overall communication network is added by using various keycodes such as a time varying keycode that determines the exact spatial beam scanning sequence required for both proper encoding and decoding of the 2-D code information. This paper describes preliminary experiments using a simple 1-D amplitude modulated spatial code. (C) 1996 Society of Photo-Optical Instrumentation Engineers.

Journal Title

Optical Engineering

Volume

35

Issue/Number

9

Publication Date

1-1-1996

Document Type

Article

Language

English

First Page

2487

Last Page

2498

WOS Identifier

WOS:A1996VG76400009

ISSN

0091-3286

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