Security enhancement in free-space optics using acousto-optic deflectors
Security enhancement in free-space optics using acousto-optic deflectors
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DOI：
10.1364/jocn.6.000684
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发表时间：
2014-08
期刊：
影响因子：
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通讯作者：
Mina Eghbal;J. Abouei
中科院分区：
文献类型：
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作者：
Mina Eghbal;J. Abouei
在本文中，我们提出了一种新的用于光束传输的物理层设计，以提高地面自由空间光通信系统的数据安全性。光发送器使用带有合成全息光栅的声光偏转器(AOD)通过发送器和接收器之间的不同光束路径发送连续的分组。增加光链路上光束的半径和强度会增加窃听的可能性；然而，这些参数对大气湍流很敏感。更准确地说，随着大气湍流的增加，光束的半径增大，而光束的强度减小。因此，如果基于强湍流来调整光束的强度，以便在接收器处接收足够的强度，则当大气湍流减少时，光束的强度增加，这导致链路安全性降低。我们推导了发射端的光束设置，其中AOD的参数变化会导致高斯光束转变为具有不同参数的二次高斯谢尔模型(GSM)光束。对于这种情况，数值模拟结果表明，在不同的大气湍流条件下，通过改变AOD的参数，可以控制不同光路上的光束半径。此外，在不同的湍流条件下，比较了安全FSO收发信机中调整后的光束半径与理想高斯光束和理想GSM光束的半径。
In this paper, we propose a novel physical layer design for beam transmission that enhances the data security in a terrestrial free-space optical (FSO) communication system. The optical transmitter sends successive packets through different beam paths between the transmitter apertures and the receiver apertures using acousto-optic deflectors (AODs) with synthetic holographic gratings. Increasing the radius and intensity of the beam at the optical link raises the probability of eavesdropping; however, these parameters are sensitive to atmospheric turbulence. More precisely, as atmospheric turbulence increases, the radius of the beam increases while the intensity of the beam decreases. Thus, if the intensity of the beam is adjusted based on the strong turbulence in order to receive sufficient intensity at the receiver, then the intensity of the beam increases when atmospheric turbulence decreases, which causes the link security to be reduced. We formulate the beam settings at the transmitter where the AOD's parameters are varied, which cause the Gaussian beam changes to the secondary Gaussian Schell-model (GSM) beam with different parameters. For such a situation, it is demonstrated, analytically supported by simulation results, that the radius of the beam at different beam paths can be controlled by changing the AOD's parameters in different atmospheric turbulence. In addition, the radius of the adjusted beam in the secured FSO transceiver is compared with that of the ideal Gaussian and the ideal GSM beams in various turbulence conditions.