Research On Mode Division Multiplexer And Demultiplexer Based On Ring Core Fiber

As an effective method to improve channel capacity,mode division multiplexing technology is particularly important today when the communication demand is growing rapidly.Two new types of mode division multiplexer and demultiplexer are proposed.The first kind of multiplexer and demultiplexer uses refractive index step ring core fiber as mode transmission channel,uses ring core channel structure and large effective refractive index difference between modes(>1×10^3-to effectively reduce mode crosstalk and improve mode extinction ratio.Pure silica core is used to effectively reduce transmission attenuation and weld attenuation.The multiplexing and demultiplexing of LP01,LP11a and LP11b modes in ring core type few mode fiber can be realized.The performance index of mode division multiplexer is studied by beam propagation method.The variation of mode coupling length with channel spacing and the relationship between mode coupling efficiency and extinction ratio of multiplexer and demultiplexer with different incident wavelengths are studied.The coupling efficiency of the mode division multiplexer is better than-7.83dB in 1400nm-1700nm band and-1.39dB in C band.In the 1400nm-1700nm band,the extinction ratio of the three modes is better than that of 28.13dB.In C band,the extinction ratio of LP01 mode is greater than 48.13 dB,which is 11.76 dB higher than that of LP11 mode.The extinction ratio of the three modes is better than 35.42dB.The intrinsic losses of few mode ring-core transmission channels are all 0.154 dB/km at 1.54?m.The second kind of multiplexer uses refractive index step ring core fiber as mode transmission channel and single mode fiber as coupling channel.The ring core channel structure and large effective refractive index difference between modes(>1.9×10^-3 are used to effectively reduce mode crosstalk and improve mode extinction ratio.Pure silica core is used to effectively reduce transmission attenuation and weld attenuation.The(de multiplexing of LP01,LP11a and LP11b modes in ring core type few mode fiber can be realized.The performance index of the mode division multiplexer is studied by using the beam propagation method,the variation of the mode coupling length with the channel spacing,and the relationship between the mode coupling efficiency and extinction ratio of the multiplexer and demultiplexer with different incident wavelengths are studied.The coupling efficiency of the mode division multiplexer in C-band is better than-0.268dB,and the extinction ratio of the three modes is better than that of 22.23dB.