Theoretical And Experimental Study Of Reflective Modulators In Coherent Optical Communication Systems

The development of optical fiber communication has benefited from the increasing demand for global network communication and data communication.With the rapid development of various terminals and applications such as 5G network,VR/AR,cloud computing,etc.,the trend of high data traffic growth is increasing,and bandwidth is increasing.Demand is getting higher and higher.At present,the widely used coherent optical communication system uses the optical phase-locked loop(OPLL)and digital signal processing(DSP)to solve the problem that the local oscillator and the signal light cannot be completely matched in the system.This design is difficult and will affect the performance of the system.In order to avoid such problems,this paper presents a new type of reflective coherent optical communication structure as an attempt to place the laser on the receiving end.The optical carrier signal is reflected back at the transmitting end and modulated to enter the optical fiber transmission.The design of the laser avoids the use of optical phase-locked loops and can be applied to secure communications or some special applications in fiber-optic communication systems with potential value.In this paper,from the theoretical analysis,simulation and experimental research,the feasibility of the new reflective synchronous homodyne coherent optical communication system scheme is verified.This paper briefly introduces the development of optical fiber communication,the classification and development status of technology in coherent optical communication.Then,as a key device in coherent optical communication,the modulation type and principle of lithium niobate electro-optic modulator,the mismatch of microwave and light wave,the signal transmission process under normal transmission,and the new reflective lithium niobate Signal transmission in modulation mode.According to the actual application,select and adjust the key parameters of the lithium niobate modulator to achieve the requirements of this experiment.After the theoretical verification scheme is feasible,the model design block diagram of the reflective homodyne optical communication system is given.The structure and principle of the BPSK and DP-BPSK homodyne optical communication system are elaborated.The balanced detection technology used in the polarization detection is used.The modulation and demodulation principle is also introduced,and the signal transmission process is analyzed.Then,the simulation of the reflective homodyne coherent optical communication system is carried out by using MATLAB and OptiSystem simulation software.According to the simulation results,the constellation diagram,Q factor,eye diagram,bit error rate and polarization state diagram of the system are analyzed in detail,which reflect that the reflective coherent optical communication system has completed correspondingly within the error tolerance.Modulation and demodulation,the system performance is good.Finally,through practical methods,the parameters and price of the market devices are investigated,the experimental equipment that meets the requirements of the system is selected,and the experimental platform is built to further verify the feasibility of the reflective homodyne optical communication system.In this paper,through two experimental comparisons,the experimental demonstration of the traditional coherent optical communication system is first carried out.The size of the demodulated signal can be obtained from the frequency response effect,and then the experimental test of the reflective homodyne optical communication is carried out.The result is also expected.Within the effect.Analyze the possible causes of the problem and propose an improved solution to the design of the system.By comparing the effects achieved by the two experiments,analyzing the performance of the system,comparing the types of devices used,and analyzing the difference in cost,the reflective synchronous homodyne coherent optical communication system designed in this paper is feasible,and has practical application.Potential value.