A low crosstalk seven-core five-mode fiber for high density transmission and large capacity communication

We propose a seven-core five-mode fiber with air hole-assisted and high refractive index ring structure, and it can be fabricated by the stack-and-draw technique. The air hole auxiliary structure can significantly restrain the energy coupling between cores, and the high refractive index ring structure can meet the requirements of low intra-core crosstalk (XT) by improving the effective refractive index difference (Δ n eff ) between adjacent modes. Through analyzing the influence of the number and arrangement of air holes on inter-core XT and effective mode field area ( A eff ), it can be achieved the results that the inter-core XT is less than −44 dB/100 km and all the A eff values of LP modes are greater than 100 μ m 2 in the seven-core five-mode fiber when the wavelength is 1550 nm and the bending radius ( R ) is 80 mm. At the same time, the Δ n eff between LP 21 and LP 02 mode can be controlled to 1.3 × 10 −3 by adjusting the parameters of the high refractive index ring. In addition, the relative core multiplexing factor (RCMF) of the seven-core five-mode fiber is as high as 88.34. The simulation results show that the seven-core five-mode fiber has high spatial density and is suitable for the communication system with multi-channel and long-distance transmission.