Free-Space Transmission and Detection of Variously Polarized Near-IR Beams Using Standard Communication Systems with Embedded Singular Phase Structures.

Sergey V Karpeev,Nikolay A Ivliev,Sofia V Ganchevskay,Svetlana N Khonina,Vladimir V Podlipnov

doi:10.3390/s22030890

Abstract

We propose to achieve multichannel information transmission in free space by means of variously polarized beams. The interaction of vortex beams of various orders with the main polarization states is theoretically analyzed. The passage of beams with different polarization states through multi-order diffractive optical elements (DOEs) is simulated numerically. Using the simulation results, tables of code correspondence of diffraction order numbers to the presence of phase vortices in the analyzed beams are constructed, which allow one to determine diffraction orders that carry information about various polarization states. The performed experiment made it possible to study the recognition of the first order cylindrical polarization state formed by a Q-plate converter using a phase DOE. In the experiment, these elements were built into a commercial fiber-optic communication system operating at the near-IR frequencies. After detecting the beam polarization state, beams of the required diffraction orders are efficiently coupled into optical fiber using an additional phase element. The developed optical detection system also provides channel suppression of homogeneously polarized components, which are supposed to be used for transmission of other channels.

Highlights

Multichannel data transmission in free space can be achieved by means of laser beams with different properties [1,2]
The most common approach is the use of vortex beams of various orders [3,4,5,6,7], as well as cylindrical vector beams [8,9]
An integral part of the implementation of optical communication is the multiplexing of the transmitted signal and the demultiplexing of the received signal on the receiving side, which in both cases rely on the use of special optical elements based on diffraction gratings [13,14,15,16,17]

Summary

Introduction

Multichannel data transmission in free space can be achieved by means of laser beams with different properties [1,2]. The use of vortex phase elements in combination with tight focusing and high-aperture diffractive axicons [25] makes it possible to distinguish between certain types of polarizations (in particular, to distinguish radial and azimuthal first-order polarizations) and optical vortices of the first and second orders.

Results

Conclusion