Channel investigation of free-space optical systems using degree of polarization modulation

Le résumé fourni par la source

Abstract In virtue of the theoretical invariance of the degree of polarization (DOP) of an optical beam propagating through atmospheric turbulence, it should be highly beneficial to use DOP based modulation in free-space optical (FSO) systems for combating the turbulence. In this work, we first present a recapitulation of the DOP calculation formalism, and the DOP invariance principle for conventional partially polarized beams in turbulent media, followed by detailed theoretical descriptions of a tailored DOP modulation method based on a partially polarized beam that consists of a completely polarized and a completely unpolarized components. To verify the theoretical results and investigate instantaneous channel fading, two methods for the realization of the partially polarized beam propagation in wave optics simulation are developed. Compared with the normalized received intensity fluctuations, the standard deviations of the received DOP values are much smaller under the turbulence conditions ranging from weak to extremely strong. Furthermore, the corresponding statistical distributions of the received DOP and intensity as well as the illustrative performance of the DOP modulation (DOPM) and intensity modulation (IM) are analyzed to confirm the turbulence-resistant capability and performance improvement of the DOPM compared with the IM. Although a simple DOP controllable beam model is considered, this work provides not only the general channel characteristics but also the basic channel investigation methods for the FSO system using the DOPM that can also be realized by other DOP controllable beam models.

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