Design Of Lithium Niobate Electro-optic Modulator And Radio Over Fiber Network

The development of cloud computing and big data technology puts forward higher requirements on the information transmission rate of the communication system.Optical fiber can improve the carrying capacity of the communication system due to its advantages of large bandwidth,strong anti-interference ability,and low cost.One of the key devices in optical communication systems is the modulator,which plays an important role in both high-speed digital communication systems and analog communication systems.RoF technology can solve the shortcomings of poor flexibility of fiber optic cable networks.Combined with wireless communication,RoF technology improves the transmission distance and coverage of information,and greatly reduces the cost of the system by simplifying the design of central station design central station convergence of complex equipment.This article mainly includes two parts:the design of related optical waveguide devices based on LiNbO₃ material and the related design of RoF networking.The content of this paper is as follows:Firstly,the advantages of the high-speed optical communication system in response to the soaring transmission data volume and the lithium niobate modulators of the key components of RoF and RoF are briefly introduced.The corresponding physical and electrical properties of lithium niobate materials:electro-optic effects and birefringence effects are described.The basic introduction and principle analysis and derivation for electro-optic modulation and polarization multiplexing are respectively introduced,and the requirements for the principle of MZ modulation and design performance parameters of MZ modulator are proposed.Based on the multi-mode interference theory and self-image effects,a MMI coupler with output phase difference of 0 and output phase difference of 0 is designed based on lithium niobate as a coupling device in the optical waveguide design of this paper.Part of the structure.The MMI coupler with the output phase difference is the light splitting and light combining structure.The polarization multiplexed demultiplexer based on MZI structure with lithium niobate as material is designed,which provides the conditions for integration with the lithium niobate modulator.An MMI coupler with an output phase difference of 0 is used instead of the traditional Y-branch designed MZM to output a phase difference MMI coupler to replace the phase shifter structure in the traditional IQ modulation,and a lithium niobate material is designed using the MZM as an intensity modulator structure.An IQ modulator and an integrated polarization multiplexed IQ modulatorare integrated on a same lithium niobate substrate with a polarization multiplexing/demultiplexing device.The integrated modulator is a lithium terbium oxide thin film material and all adopts an MMI coupling structure.Through the analysis of high-speed electro-optic modulators,the principle of selection of traveling wave electrodes and quasi-static mathematical analysis methods are introduced.According to the corresponding relationship between z-tangential and TE and TM linear polarization of LiNb03 crystals,the work is designed to work in TE and The CPW traveling wave electrode and the MSL traveling wave electrode structure in the TM mode make the modulator can utilize the maximum electrooptic coefficient,reduce the loss of optical energy in order to obtain a single polarization state,and improve the modulation bandwidth and the modulation efficiency.Finally,it analyzes the body area network communication standard IEEE802.15.6 and ZigBee protocol standard,uses ZigBee sensor as sensor terminal,uses RoF as the basis to realize ZigBee antenna extension,and designs a RoF-based distributed antenna networking that bears the volume-area network related services.Using the RoF link,the long-distance sensing terminals and the central station exchange data,and the B/S architecture is used to present the data of the body-area network related data,which increases the system's coverage and information processing capabilities.