| Compared with traditional optical fibers,the cladding of microstructured optical fibers contains air holes arranged according to a certain rule,thus having extremely flexible and ad-justable structure design.Researchers can design and fabricate microstructured optical fibers with required characteristics by changing the arrangement and size of air holes in cladding and filling different optical functional materials in air holes according to different require-ments.Because these advantages that a large number of scholars at home and abroad have been interested in microstructured optical fibers since they were put forward in the 1990s,which has made great progress in the design,simulation and fabrication of microstructured optical fibers.At the same time,it also provides many feasible ideas for the development of micro-nano photonic devices based on microstructured optical fibers.In this paper,metal-filled microstructured optical fibers are selected as the research object,two kinds of gold-coated microstructured optical fibers are proposed and their polarization filtering and sens-ing characteristics are numerically analyzed.The silver-line microstructured optical fibers prepared by our research group are filled with liquid crystal,and their temperature sensing characteristics are tested and analyzed.The main contents are as follows:Firstly,a gold-coated macroporous modulated microstructured optical fiber is proposed.By removing part of the air holes,a larger size air hole is introduced in the area immediately adjacent to the core,which destroys the symmetry of the cladding air holes arrangement and makes the microstructured optical fibers have obvious polarization characteristics.The loss peaks of different wavelength and indensity in the x-polarization and y-polarization direc-tions are obtained.The principle of bonding surface plasma resonance,the gold nano-film is coated on the inner surface of large air holes,which makes the core mode and surface plas-mon mode resonate when light propagates.The loss in one polarization direction is much greater than that in the other polarization direction perpendicular to it.Thus,the microstruc-tured optical fibers can achieve high-efficiency polarization filtering.The influence of fiber structure parameters on the performance of microstructured fiber polarization filter is further analyzed.The results show that the y-polarization mode can be effectively filtered through 1550 nm communication window,and the polarization filtering can be realized by using micro-structured fiber with length less than 1 mm.Secondly,a microstructure optical fiber based on gold-clad groove modulation is de-signed.A groove is designed in the upper half of a microstructured optical fiber with only two air holes,and a gold nano-film is deposited on the surface of the groove.By adjusting the size of the inner air holes,the core mode can easily resonate with the surface plasma mode near the gold nano-film,and at the same time,the energy of the core can not be re-strained,so that it can escape into the cladding.By adjusting the structure parameters of the optical fiber,the liquid refractive index of the analyte can be detected and the polarized light can be filtered.The simulation results show that the designed micro-structured optical fiber has high sensitivity and resolution of refractive index detection,and can achieve polarization filtering at 1.5 μm,which is expected to be applied in sensing and filtering fields at the same time.Finally,using the Silver-Wire microstructure fiber prepared by the research group,because liquid crystal is very sensitive to temperature,a temperature sensor is made by filling the cladding pore with liquid crystal under pressure.The transmission spectra of liquid crystal filled Silver-Wire microstructured optical fibers at different temperatures were measured us-ing a broadband light source.The sensitivity of the optical fibers to temperature sensing was further analyzed,In the range of 15-50℃,the sensitivity can reach 80 counts/℃. |
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