Experimental Research Of The Mode Division Multiplexing Communication System Based On Few-mode Fiber

With the rapid development of the Internet,the cloud computing,the large data center and the application of internet of things,the demand for the network bandwidth grows at a comparative high speed.The communication network will face the enormous pressure due to the explosive expansion of the network traffic.In order to resolve the enormous pressure for the optical transport network caused by the emerging bandwidth consumption business,a variety of methods have been proposed to promote the capacity of optical network,such as wavelength division multiplexing(WDM),polarization division multiplexing(PDM),electric field time-division multiplexing(ETDM)and orthogonal frequency(OFDM),etc.These technologies are all based on single mode fiber(SMF).As these technologies unceasing development and progress,however,the capacity of single-mode fiber communication system is approaching its nonlinear Shannon limit.The capacity of the optical communication is near saturation.Mode division multiplexing(MDM)based on few-mode fiber(FMF),a novel form of multiple-input multiple-output(MIMO)optical transmission,is rapidly gaining attraction as a potential strategy for the optical network.A mode division multiplexing(MDM)system can multiply the capacity of the communication system by a factor of the number of modes.Since the mode field area in FMF is large,the nonlinear tolerance is high thus the FMF can not only improve the capacity,but can also avoid the influence of the nonlinear on the system.In this dissertation,we have researched the key technologies for MDM optical transmission system based on FMF deeply.And then a 2×2 MDM transmission system based on few-mode Fiber Bragg Grating(FBG)and a 3×3 MDM transmission system based on photonic lanterns has been established,respectively.The 10 km MDM transmission experiment of the 3×4.25 Gb/s PRBS has been achieved successfully,which are carried by LP01?LP11a?LP11b mode,respectively.The waveforms,eye-diagrams and BER are measured.The main work can be listed as follows:Firstly,the mode transmission characters in FMF is analyzed by theoretical derivation based on the Maxwell's equations.Then the important theoretical or technological problems of the mode division multiplexing communication system are illustrated,such as the few-mode fiber design,the optical components in mode division multiplexing transmission system and the impairments compensation for mode de-multiplexing in MDM system.Secondly,mode division multiplexing/de-multiplexing for MDM system is investigated.Then the structural components and the operating principle of several current mode division multiplexer/de-multiplexer(MUX/DEMUX)for MDM system are introduced in details,such as the mode MUX/DEMUX based on the free space optics,fiber mode couplers,planar lightwave circuits(PLCs),or photonic lanterns(PLs).And a comparative study is performed by considering the Performance Characteristics of these schemes.Then,we proposed a novel mode MUX/DEMUX based on few-mode FBG combined with the optical circulator.The operating principle of mode MUX/DEMUX based on few-mode FBG was analyzed theoretically.Then few-mode FBG and the optical circulator are fabricated and the feasibility of the mode MUX/DEMUX we proposed has been verified experimentally.A 2×2 MDM transmission system based on few-mode Fiber Bragg Grating(FBG)has been established.The 10 km MDM transmission experiment of the 2×4.25 Gb/s PRBS has been achieved successfully,which are carried by LP01?LP11 mode,respectively.The waveforms,eye-diagrams and BER are measured.Finally,a 3×3 mode division multiplexing transmission system has been established with the mode MUX/DEMUX based on mode selective photonic lanterns.A 3×4.25Gb/s MDM transmission over 10 km two-mode fiber is experimentally demonstrated.The waveforms and eye-diagram have been measured for back-to-back(B2B)and 10 km transmissions at different bit speed rate,respectively.At last,the BER and the stability of the 3×4.25Gb/s MDM transmission is tested.