Research On Polarization-maintaining Few-mode Fiber

In recent years,with the rapid development of technologies such as Internet communication,the world's network bandwidth and data center demand for data capacity has exploded,but the existing single-mode fiber-optic communication system is far from meeting the rapidly developing information society.The need for data capacity.For this reason,the space division multiplexing technology based on multi-core fiber or modular multiplexing is expected to solve the problem of capacity demand and is considered to be the second revolution of optical fiber communication.In a space division multiplexed fiber,The polarization-maintaining few-mode fiber has the advantage of being weak in nonlinearity and enabling short-distance transmission without multi-input and multi-output digital signal processing equipment.Therefore,designing and analyzing new polarization-maintaining few-mode fibers is of great significance.This thesis studies the related theory of polarization-maintaining mode-mode fiber.The polarization of the three new structures maintains a small mode fiber.The main work of this thesis is:1.Theoretical research on polarization-maintaining few-mode fiber is earried out,and its mode characteristics,waveguide characteristics and polarization-maintaining realization principles are analyzed,including mode field distribution,group velocity dispersion,effective area of fiber and splicing loss.2.The transmission characteristics of rectangular core few-mode fiber are analyzed.Based on the stress realization principle,the rectangular core polarization-maintaining few-mode fiber is designed and analyzed.The mode characteristics and waveguide characteristics of the fiber are analyzed,and the transmission performance of the fiber is studied.The fiber can support effective separation of at least 8 modes,and has a large effective area,which increases the propagation distance of the degenerate mode,and proves that it can be used for short-distance applications such as data center interconnection and optical access network.3.The realization principle of the geometrically biased polarization-maintaining few-mode fiber is analyzed.Based on the rectangular shape,the ring-shaped rectangular polarization-maintaining few-mode fiber is designed and implemented.The fiber can support the effective separation of 10 modes,and the utilization rate of the spatial channel reaches 100%.The group velocity dispersion values of the 10 modes on the C-band and L-band are in the range suitable for short-distance transmission,and have the potential to become a transmission medium for futur-e space-division multiplexed optical fiber communication.4.The effect of air holes on the polarization-maintaining few-mode fiber was studied and the air hole-ring core rectangular polarization-maintaining few-mode fiber was designed.Studies have shown that the size and position of the air holes have a large influence on the transmission performance of the optical fiber.The polarization-maintaining mode-less optical fiber that introduces the air hole can support the effective separation of the 14 mode,further improving the transmission capacity.