全光混沌序列发生器设计

Design of All-optical Chaotic Sequence Generator

如何在光域产生混沌序列并将其作为光码分多址OCDMA(optical code division multiple access)系统的地址码,是近年来一个新的研究方向。利用马赫-增德尔干涉仪设计了一种完全在光域产生模拟双极性混沌序列的发生器。通过控制马赫-增德尔干涉仪两臂引起的相移来调制输入光电场的振幅和相位,使得输出光电场矢量等于输入光电场矢量与余弦项的乘积,多个干涉仪及光纤延迟线和相移器可以构成混沌序列发生器,并按logistic映射在光域产生双极性混沌序列。此混沌序列发生器可作为OCDMA系统的编解码器,提高保密性并增加系统可容纳的用户数。

How to generate a chaotic sequence in an optical domain and it is used as an address code in an optical code division multiple access （OCDMA） system is a new research direction in recent years. A generator producing simulated bipolar chaotic sequences completely in optical domains is designed by a Mach-zehender interferometer. The amplitude and phase of an incident light field are modulated by controlling the phase shift of two arms on the Mach-zehender interferometer. So the vector of output optical field is equal to the product of input optical field vector and the cosine item. A chaotic sequence generator is made up of several interferometers, optical fiber delay lines and phase shifters. And a bipolar chaotic sequence is generated in an optical domain according to logistic mapping. The chaotic sequence generator can be used as the encoder and decoder of the OCD- MA system to improve security and increase numbers of users accommodated by the system.