| Due to the flexible structural design,photonic crystal fibers have many excellent characteristics that traditional fibers do not have.Material filling in the pores of optical fiber can greatly improve its performance and expand its application range.With the advantages of small size,adjustable microstructure and easy integration of photonic crystal fibers,making it into photonic devices has become a new research hotspot in the field of optoelectronic devices,and is also increasingly favored by researchers and fiber manufacturing enterprises.In this paper,the polarization filter,refractive index sensor and polarization beam splitter based on photonic crystal fiber were designed from two aspects of structure design and material filling.Through in-depth experimental exploration and theoretical analysis on the fabrication technology of photonic crystal fiber,the secondary drawing and air pressure control technology for fabricating photonic crystal fiber were obtained.Photonic crystal fibers with various structures were fabricated,and the bending and temperature sensing experiments of the fabricated multi-core photonic crystal fibers were carried out.The main work of this paper includes:(1)Three kinds of single communication band polarization filters based on photonic crystal fiber were designed.and their performances were analyzed in depth.One is the V-structure photonic crystal fiber polarization filter,which has a confinement loss of 434dB/cm in the y polarization direction at the communication wavelength of 1.31?m.When the fiber length is 1000?m,the corresponding crosstalk value is 353.74dB.The other is a photonic crystal fiber polarization filter with two kinds of lattice arrays.After filling the liquid analyte,the core loss in y polarization direction is 572.55dB/cm at the wavelength of 1.55?m.When the fiber length is 800?m,the corresponding crosstalk value is 379.75dB.The third is a gold-coated high birefringence photonic crystal fiber polarization filter.At the communication wavelength of 1.31?m,the loss of the core mode in y polarization direction can reach 924.96dB/cm.When the fiber length is 500?m,the corresponding crosstalk value can reach 389.15dB.(2)Two kinds of dual communication band polarization filters were designed,which can achieve high performance polarization filtering at the communication wavelengths of 1.31 ?m and 1.55?m simultaneously.One of them is a rectangular lattice dual communication band photonic crystal fiber polarization filter.At the communication wavelengths of 1.31?m and 1.55?m,the confinement losses are 569.83dB/cm and 719.25dB/cm respectively.When the fiber length is 700?m,the corresponding crosstalk values are-335.62dB and 407.87dB respectively.After filling the liquid,the confinement losses at the two communication wavelengths are 831.7dB/cm and 580.53dB/cm respectively.When the fiber length is 700?m,the corresponding crosstalk values are-493.86dB and 323.67dB respectively.The other is octagonal two-band photonic crystal fiber polarization filter.At the communication wavelengths of 1.31?m and 1.55?m,the confinement losses are 542.78dB/cm and 729.47dB/cm respectively.When the fiber length is 700?m,the corresponding crosstalk values are 31 8.59 dB and-412.73dB respectively.(3)Two kinds of photonic crystal fiber refractive index sensors were designed,one of which is a high sensitivity sensor based on double-core coupling,and its sensitivity can reach 22071nm/RIU.The other is a gold-coated eccentric optical fiber sensor with circular pores,and its sensitivity is 4939.29nm/RIU.The sensor is a gold-plated film on the outer edge of the optical fiber,and its preparation process is much easier than the gold-plated film on the inner wall of the air hole and the gold-plated film on the polished surface after polishing into D-shape,and the liquid analyte can be monitored in real time.In addition,a two-core photonic crystal fiber polarization beam splitter with extremely short beam splitting length and circular arrangement of pores was designed.The shortest beam splitting distance is 72.43?m,and the extinction ratio is-151.42dB at the wavelength of 1.55?m.(4)A step stacking method was proposed to prepare photonic crystal fiber preform.The experiments of primary and secondary drawing photonic crystal fibers were compared and studied,and the key technologies of secondary drawing were analyzed in detail.Through reasonable adjustment of high temperature furnace temperature,rod feeding speed and pulling speed,the diameter of photonic crystal fiber was successfully reduced to standard size 125 ?m by adopting secondary drawing technology,and single-core photonic crystal fiber,double-core photonic crystal fiber,central seven-core photonic crystal fiber,dispersed seven-core photonic crystal fiber,central large pore band gap photonic crystal fiber and single hollow band gap photonic crystal fiber were prepared.(5)The role of air pressure control technology in the regulation of optical fiber microstructure has been deeply studied.The core size of photonic crystal fiber was successfully reduced to below 4?m by using external sleeve and air pressure control technology.Single-core photonic crystal fibers,double-core photonic crystal fibers,seven-core photonic crystal fibers,panda-type photonic crystal fibers,V-type photonic crystal fibers,fan-type photonic crystal fibers and grapefruit-type photonic crystal fibers were fabricated through coordinated control of air pressure threshold,high-temperature furnace temperature,rod feeding speed and traction speed.Single silver-wire photonic crystal fiber,double silver-wire photonic crystal fiber and panda-filled silver-wire photonic crystal fiber were fabricated by adding silver wire into capillary tubes.The obvious surface plasmon resonance phenomenon was detected in the measurement of panda-silver-wire photonic crystal fiber.(6)Two-core optical fiber,partial double-core optical fiber and three-core optical fiber prepared by the research group were made into bending sensors,and bending sensing experiments and temperature sensing experiments were respectively carried out after the bending sensing system and the temperature sensing system were built.When the length of the two-core sensing fiber is 207mm,the curvature sensitivities measured in the forward and negative directions are 4.64364nm/m-1 and-4.648nm/m-1.respectively,and the bending direction of the sensing fiber can be discriminated by the curvature measurement.The measured temperature sensitivity is-13pm/?.When the length of the partial double-core optical fiber is 105mm,its curvature and temperature sensitivity are-3.83993nm/m-1 and 21pm/? respectively.When the length of the three-core sensing fiber is 150mm,its curvature and temperature sensitivity are-7.27039nm/m-1 and-20pm/? respectively.When the length of the three-core sensing fiber is 68mm,its curvature and temperature sensitivity are 2.42419nm/m-1 and-7pm/?respectively,and the cross interference caused by temperature to curvature is very small. |
PDF Full Text Request