Polarization Maintaining Spatial Division Multiplexing Fiber And Its Applications

Due to the deployment of new generation mobile communication network and the fast development of information communication technology(ICT),both human lifestyle and social management have been profoundly promoted.In order to improve the transmission capacity of global fiber optical network,the motivation of exploring new ultra-large information transmission technique has become worldwide research topic for future fiber optical communications.Because of nonlinear Shannon effect,the transmission capacity of standard single-mode fiber(SSMF)is approaching its capacity limit.Since the potential multiplexing dimensions of optical signal in terms of wavelength,polarization,and time have been comprehensive investigated.As the last possible multiplexing dimension of optical signal,space division multiplexing(SDM)technique is widely believed as a sustainable solution to satisfy the ever-growing demand of fiber optical transmission capacity.My Dissertation is focused on the polarization maintaining characteristics of SDM fibers and its application,including the design fabrication and characterization of PANDA-type elliptical core polarization-maintaining few-mode fiber(FMF),design and numerically evaluation of PANDA-type polarization-maintaining four-core fibers,and all-fiber flexible generation of generalized cylinder vector beams(CVBs).The main research outcomes of Dissertation are summarized as follows:(1)We design and fabricate PANDA-type elliptical-core FMF supporting 6 guided modes,including LP_01x,LP_01y,LP_11ax,LP_11ay,LP_11bx,and LP_11by.The minimum effective refractive index difference among the guided eigenmodes is more than 3×10^-4 over C+L band.Consequently,both spatial and polarization degeneracy arising in the FMF is completely mitigated.Meanwhile,we experimentally carry out evaluation of polarization maintaining characteristics for all guided modes,by twisting the fabricated FMF.When the twisting rate is no more than 1.5 rad/m,the correlation coefficients of all captured mode profiles of all eigenmodes are more than 90%,and the corresponding polarization extinction ratio is more than 20dB.(2)We design the Panda-type four-core single mode fiber.In comparison with traditional Panda-type polarization-maintaining single mode fiber,we can save half of the stress rods,indicating of the reduction of fiber fabrication cost.Our numerical results indicate that the crosstalk between adjacent cores is better than-40dB/100km,and the birefringence of individual core is larger than 3×10^-4,over the wavelength range from 1288nm to 1630nm.Such fiber can satisfy the requirement of polarization maintaining applications,while its optical properties,such as chromatic dispersion,chromatic dispersion slope,and mode field area,are comparable with the SSMF.(3)We theoretically find the generation strategy of generalized CVBs by the rotation manipulation of either polarization orientation or mode profile orientation for two superposition HG modes.Then,an all-fiber CVB generation setup is demonstrated,with the help of novel all-fiber polarization controller and fiber rotator,in order to realize either polarization orientation or mode profile orientation rotation manipulation of HG mode without profile distortion.The feasibility of the theory is verified by the implementation of all fiber setup.Our experimental characterization results verify that there occurs almost no performance penalty over the C-band between two all-fiber rotation manipulation methods.