Design And Characteristics Study Of Novel Few Mode Fibers

Single-mode optical fiber communication faces Shannon limit,and the technology of mode division multiplexing communication based on few mode optical fiber has been a research hotspot in the field of optical fiber communication.In the face of a lot of information demand,it is needed and necessary to realize the high efficiency and high quality of the few mode optical fiber communication system.The design of few mode optical fiber with low nonlinear effect,low crosstalk,low loss and low bending loss will be an important method and way to solve those problems.This paper mainly focuses on the design and research about transmission characteristics of the few mode optical fiber,mainly innovative work as follows:1.A three-ring-core few-mode fiber with large effective area and low nonlinear coefficient is presented,which combines the concept and advantages of ring core few mode with that of multi-core supermode fiber and realizes supermode transmission with four linear polarized modes.The study result shows the proposed fiber has good properties,such as high mode density,large effective mode area,low nonlinear coefficient,low bending loss and low difference group delay;the nonlinear coefficient and differential mode group delay of this fiber performs flattened profile from the wavelength of 1.3 ?m to 1.6 ?m,and four supermodes have low bending loss in the range of 1.4 ?m to 1.48 ?m.In conclusion,the three-ring-core few-mode fiber can be applied to high power pump few mode optical amplifier,such as Raman amplification pump and high power remote pump Erbium Doped Fiber Amplifier.In addition,this fiber with low differential mode group delay,which could reduce the complexity of multi-input multi-output process.If the fiber bending radius is larger than 0.3 m,the proposed fiber can be applied in optical transmission.Compared with fundamental mode of the single core multimode fiber with equivalent size and effective refractive index,the three-ring-core few-mode fiber our supermode has good performance with large effective refractive index difference,low bending loss and low difference mode group delay.2.A graded index few mode optical fiber with large effective mode area,low crosstalk and low loss is proposed.The few mode fiber core is pure silica to reduce fiber loss,refractive index of core is graded,cladding index is trench,which combines the low loss of pure silica fiber with low differential mode group delay of graded index fiber and achieves two mode transmission.The study result shows that the proposed fiber has good properties,such as large effective area,low nonlinear coefficient,low differential mode group delay and low loss;the nonlinear coefficient and differential mode group delay of this fiber performs flattened profile from the wavelength of 1.43 ?m to 1.8 ?m,and the effective mode area is about 6-9 times as large as that of standard single-mode fiber(SSMF)and the nonlinear coefficient is much smaller than SSMF.