Research On Graphene Coated Photonic Crystal Fiber Polarization Devices

With the new wave of information technology,the development of emerging industries such as big data,AI,and cloud services has brought greater demand for the capacity and speed of communication networks.All-optical communication networks can provide larger communication capacity and higher long-distance transmission speed,which will establish a solid foundation for high-speed,stable and reliable development of the information society.Combining new technologies and new materials to develop high-performance fiber optic devices is the key to the development of all-optical communication networks.Graphene-based polarization beam splitters and polarization converters exhibit excellent polarization properties and novel modulation characteristics,and have become a research hotspot of new optical devices in recent years.Graphene polarization devices based on planar waveguides will cause large losses when integrated into all-optical networks,which limits their applications.Therefore,new graphene-based fiber polarization devices have practical necessity and certain development potentials.As a flexible microstructure optic fiber,photonic crystal fiber can be combined with graphene to realize fiber polarization splitting and conversion devices for specific functions.Under this background,the research contents of this paper are as follows:(1)A dual-core photonic crystal fiber polarization beam splitter coated with graphene layers in the central air hole is analyzed.The device achieves almost complete polarization splitting at a fiber length of 100.8 ?m.At a device length of 502.57?m,with the graphene chemical potentials of 0.6eV and 0.87eV,the polarization extinction ratios are 90dB and-58dB respectively.(2)A polarization beam splitter based on D-type dual-core photonic crystal fiber with graphene coated on the polished surface is analyzed.It can modulate the coupling length of x-polarization direction without affecting y-polarization direction.When the device length is 535.8?m,the output extinction ratio of cross port can vary from-29.3 dB to-65.5dB.(3)A polarization beam splitter based on dual-core coupling system composed of two D-type photonic crystal fibers with graphene coated on the connecting surface is analyzed.The coupling length of the y-polarization direction can be modulated without affecting the x-polarization direction.When the device length is 258.5?m and 361.9?m,the y-polarization output power can be switched between the through port and the cross port.Besides,the loss in the modulation interval is relatively low.(4)A polarization beam splitter-converter based on D-type dual-core photonic crystal fiber with graphene coated on the surface of an opened air hole is analyzed.The device can modulate the coupling lengths of both x and y polarization directions at the same time.When the device length is 2996.4?m,the output extinction ratio varies between-48.2dB and 50.9dB in the modulation interval with lower loss,and the polarization conversion function can be realized.All fiber structures coated with graphene proposed in this paper can be used to realize compact polarization beam splitters with high extinction ratio,and have adjustable output power and the ability of polarization conversion,which have shown great application prospects in all-fiber networks.