Structure Design And Simulation Analysis Of Large Effective Area Low Loss Optical Fiber For Underwater Optical Communication

Although the exploration of the ocean has never been made,so far,there are still many unknowns in the sea,because human understanding of the sea is mostly limited.Underwater optical cable plays an important role in the study of marine technology,and is the main transmission medium of submarine optical fiber cable communication.Underwater optical cable communication has the advantages of high communication speed and large capacity,and has become an important transmission medium for realizing long-distance international communication.However,the communication performance will be affected due to the complicated environment,like laying and maintenance difficulties.The background of this research is briefly introduced,and the structure of the existing optical fiber and optical cable are analyzed.Then,the four theoretical models of light analysis has been research.The following three parts are the main work of this article.Firstly,a new double row eight side exhaust port fiber is designed by referring to the perforating structure of photonic crystal fiber.After setting parameters such as optical fiber pore diameter and hole spacing,COMSOL is used to simulate it.The results show that the effective area of the fiber is up to 4491.00?m2 at the wavelength of 1550nm.The structure design of optical fiber with large effective area is realized.The effective area of optical fiber has been improved effectively.Secondly,the structure of low dispersion and large effective Step-Index Fiber is designed based on the basic step fiber structure.The fiber core is divided into two parts.The cladding is divided into three parts.The simulation results show that the dispersion value of the fiber is lower than that of 2.50ps/km·nm at the wavelength ranged from 1200nm to 1700nm,and the maximum diameter of the effective mode field can reach 12.20?m.It is proved that the fiber has the characteristics of smooth dispersion and large effective area.The ray is optimized by changing the refractive index and radius of the concave layer of the core.When the radius of the core recess is 3.26?m,the effective mode field diameter is higher than 50.O00?m,and the dispersion is lower than 4.00ps/km·nm.Finally,a graded fiber structure with low bending loss and low dispersion is designed by referring to the basic gradient fiber structure.The fiber core is divided into two parts.The cladding is divided into 4 parts.The simulation results show that when the optical fiber works at 1550nm,the zero dispersion point of the fiber moves to 1520nm,the dispersion value is less than 4.00ps/km·nm,but not zero so that the fiber has the characteristics of low dispersion.At the same time,when the bending radius is 38cm,the bending loss of the fiber is 10-3 dB/km orders of magnitude at 1200-1700nm.So the fiber has the characteristics of low bending loss.By doping the core to form a lower concave layer,the zero dispersion point of the optical fiber can be effectively controlled by changing the radius and refractive index of the lower concave layer.The result is that the optical fiber has low dispersion characteristics at working wavelength.