| With the rapid development of technologies such as mobile Internet,cloud computing services,and the Internet of Things,the requirements for Internet communication speed and capacity have increased rapidly [1.1].The total amount of social network information is expected to increase 20-400 times in the next 10-20 years.Monitoring statistics and analysis show that the distribution of information growth is uneven,and the Global Data Center and High Performance Computer,which are responsible for the task of information aggregation,processing,storage and distribution,are hotspots of growth [ 1.2,1.3].However,within large IT facilities,communication technology has become a bottleneck that limits its capacity expansion,which is mainly reflected in the fact that existing communication technologies cannot meet the requirements for ultra-large-capacity communication(high-capacity density)in a limited space.Therefore,it is urgent to develop a new type of optical communication multiplexing technology to meet the requirements of high bandwidth,low latency,and high energy efficiency,and become the core technology for ultra-high-capacity density interconnection in data communication.We propose to study the optical communication technology of CVB: Cylindrical Vector Beam multiplexing.First of all,CVB has the potential to transmit larger information capacity than traditional orbital angular momentum(OAM: Orbital angular momentum)optical communications.This is mainly because the CVB beam is an orthogonal vector beam mode.Not only are CVBs of different orders orthogonal to each other,but CVBs of the same order also have two mutually orthogonal polarization states.For example,both radial and angular polarized light are first-order CVBs,but their polarization states are orthogonal to each other.This fully shows that CVB optical communication can theoretically achieve double the information transmission capacity than OAM optical communication.Secondly,the phase characteristics and polarization characteristics are two basic properties of a light beam.In the process of beam transmission in space,the phase characteristics are more susceptible to atmospheric disturbances than the polarization characteristics.CVB is a vector mode based on polarization orthogonality.Theoretically,transmission in anisotropic media can maintain orthogonality.And the polarization state is unchanged.Therefore,CVB is theoretically more resistant to atmospheric turbulence or mode crosstalk in non-uniform waveguides.Finally,in terms of optical fiber communications,extrinsic mode light beams cannot be stably transmitted in optical fibers due to the optical wave mode selectivity of optical fibers.By solving the wave equation in the optical fiber theoretically,the CVB beam is an intrinsic solution in the optical fiber.Therefore,it is of great scientific and practical significance to study the optical communication technology based on CVB multiplexing.The main research results of this paper are as follows:1 The transmission of CVB in air-core photonic crystal fiber was verified,and multiplexed communication experiments were performed.First,the cross-sectional view of the photonic crystal fiber was taken with SEM,and then the electromagnetic frequency domain simulation of the optical fiber was performed in COMSOL based on the cross-sectional view to calculate the optical fiber.The number of supported modes,mode refractive index,loss,and other parameters are then verified by CVB transmission in the photonic crystal fiber.It is concluded that it can support up to 4th order CVB,and finally performs multiplexed communication experiments.2 Designed a low-loss,air-core anti-resonant fiber that supports high-order CVB transmission.Based on the principle of anti-resonant fiber,design an anti-resonant fiber structure that meets our goals,while meeting low latency,low loss,and low dispersion,capable of transmitting high-order CVB,summarizes the design process and draws general rules,and pave the way for subsequent communication experiments. |
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