Research Of Micro-Structured And Multi-Material Hybrid Polarization-Maintaining Fiber Design

Since the 21st century,the rapid developments of Internet platforms such as cloud computing,big data,and the Internet of Things have led to huge challenges in data transmission capacity,and optical fiber transmission capacity is gradually approaching the capacity bottleneck.Therefore,in order to further improve the data transmission capacity of network communication,the capacity expansion of optical fiber is urgent.In order to solve the contradiction between the number of modes,transmission performance（loss,crosstalk,dispersion）and production cost of hollow-core fiber and few mode fiber.In this context,based on"few mode+polarization-maintaining"of space division multiplex,researches have been carried out,including based on hollow-core anti-resonant reflecting fiber,micro-structured air-hole-assisted few mode fiber to realize modes polarization-maintaining multiplex,and the negative permittivity hybrid material fiber to realize"few mode+single polarization"multiplex.The main results of the thesis are summarized as follows:1.Based on the guiding mechanism of anti-resonant reflecting optical waveguide,a polarization-maintaining hollow-core anti-resonant reflecting fiber with multiple anti-resonant layers supporting two polarization-maintaining modes is proposed.The effects of the number and thickness of anti-resonant layers,the size of the air core,and the distance between two adjacent anti-resonant tubes in the orthogonal direction on the effective refractive index difference and losses between modes are investigated.The effective refractive index difference between the two polarization states of the fundamental mode(HE_11x and HE_11y)is higher than 1.0×10^-4 in the range of 1425nm-1725 nm（the bandwidth is 300 nm）,the losses are 0.002 d B/m-0.185 d B/m,and the dispersion is less than 45.51 ps/nm/km.At 1550 nm,the effective refractive index difference between HE_11x and HE_11y is 1.2×10^-4,and the losses of HE_11x and HE_11y are0.002 d B/m and 0.013 d B/m respectively.In addition,the bending loss is less than 0.2d B/turn when the bending radius of the fiber is more than 2 cm along the x or y axis.2.By introducing an elliptical air-hole in the center of the elliptical ring core,and introducing circular air holes of different sizes in the horizontal and vertical directions respectively,a micro-structured air hole-assisted polarization-maintaining few mode fiber supporting 10 modes is proposed.The effects of the size and position of the circular air holes,the size and ellipticity of the ring core,and the size and ellipticity of the elliptical air hole on the mode effective refractive index and the effective refractive index difference are investigated.10 orthogonal modes are supported in the wavelength range of 1520 nm-1600 nm（the bandwidth is 80 nm）,and the effective refractive index differences between all adjacent modes are higher than 1.0×10^-4.In the wavelength range,the dispersion is less than 51.3 ps/nm/km.3.A hybrid material single polarization fiber is proposed by filling negative permittivity material near the fiber core.The influences of negative permittivity material size and position on the losses of the two polarization states of the fundamental mode are studied when the negative permittivity materials are Au and Aluminum doped Zinc Oxide.The simulation results show that when Au is used as negative permittivity material,the loss ratio of the two polarization states of the fundamental mode is larger,the losses of HE_11xand HE_11y are 6.799 d B/m and 0.269 d B/m respectively,and the optimal loss ratio is25.28.According to the above researches,the Au hybrid material single polarization few mode fiber is studied.The simulation results reveal that HE_11y,HE_21y and TM₀₁ can not meet the limitation of transmitting with low loss simultaneously.Finally,the Au hybrid material single mode single polarization fiber is designed.