| In recent years,5G technology has developed rapidly.With the proposition of the photoelectric circuit boards,optical interconnection has gradually replaced electrical interconnection and has become one of the current mainstream chip interconnection technologies.As an important part of optical interconnection technology-passive optical devices,has also become a popular research object.Among them,the traditional Y-branched optical waveguide power splitter has very large limitations in size design due to its special Y-branch structure,and it has never been able to meet the needs of high integration of optical devices.However,polymer optical splitters used in EOPCB mostly use photolithography technology,and the manufacturing steps are cumbersome,and the manufacturing accuracy depends entirely on the accuracy of the photolithography technology.The manufacturing method of polymer optical splitters lacks high efficiency in actual production.In order to solve the above problems,this paper has made research and improvement on the structure and materials of the Y-branch optical splitter,and prepared an air-clad polymer rectangular Y-branch 1x16 optical splitter.The specific research work is as follows:（1）Based on the theory of beam propagation method,a new type of Y-branch rectangular optical splitter is proposed,which is a symmetrical and asymmetrical hybrid structure.The optical splitter has been greatly reduced in size.The cladding is air,the substrate is SiO2,the core layer is SU8 photoresist,and the end face is a rectangular structure of 10x10μm.Through the simulation and optimization of each Y branch,the structure size of the complete 1x16 optical power splitter is obtained,and its length is<20000μm.The simulation results show that its insertion loss is 14.8dB and the uniformity is 0.8dB.（2）The ultrafast femtosecond laser etching is proposed as a new technical method for the preparation of polymer optical waveguide devices.By studying the relationship between ultrafast femtosecond laser parameters and the etching efficiency of polymer SU8 photoresist,a complete femtosecond laser processing technology for polymer SU8photoresist was obtained.Among them,the defocus,power,scanning speed and scanning path spacing of the femtosecond laser were studied,When the defocus amountΔf=-5μm,the laser power P=100m W,the scanning speed v=10mm/s,the scanning path spacing d=4μm,the femtosecond laser can process polymer optical waveguides with a rectangular cross section of 10x10μm.（3）The efficiency of single-mode fiber and multimode fiber when coupled with air-clad polymer optical waveguide is studied,focusing on factors such as lateral deviation,axial deviation,angle deviation,Fresnel reflection and mode field mismatch.When the single-mode fiber is used as the input fiber,the lateral deviationΔX=0μm,the axial deviationΔZ=0μm,and the angular deviationβ<8?,the maximum coupling loss is 0.4dB.When the multimode fiber is used as the output fiber,the lateral deviationΔX=0μm,the axial deviationΔZ=0μm,and the angle deviationβ<15?,the maximum coupling loss is4.6dB.（4）An optical fiber coupling test platform was built to study the performance of the power splitter.Through the light test and recording the calculation results,the insertion loss of the device was<20dB,and the uniformity was 1.42dB.A polarization sensitive coupling test platform was built.When the input linearly polarized light entered the device at different angles,the polarization sensitivity of the device was studied.When the input linearly polarized light enters the input waveguide at an angleθ=0?orθ=180?,the normalized output power is 0.035,and when the input linearly polarized light enters the input waveguide at an angleθ=90?orθ=270?,the normalized output power is 0.Through the simulation software,the thermal stability of the device under different working environments has been studied.The device still has good structural stability in the normal working environment of-40?C～80?C.The maximum deformation variables under-40?C and 80?C are 50e-5μm and 15e-5μm,which are much smaller than the allowable deformation threshold of 0.1μm,it has good thermal stability. |
