Research On Degradation Mechanism Of Airborne Optical Fiber Connectors Under Different Environments

With the rapid development of the optic fiber communication industry,optical fiber connectors are increasingly used in the fields such as aerospace,which has put forwards more stringent requirements for their reliability.Airborne optical fiber connectors are often subjected to complex working conditions such as special temperatures,vibrations,and various atmospheric environments during the aircraft operation,which increases the risk of connector failure.Once a connector fails,it affects the normal transmission of the entire link,endangering the safety of the onboard system.Therefore,it is important to investigate the possible degradation mechanism of optic fiber connectors in complex airborne environments.This study takes the J599E8 beam expanding optical fiber connector as the research object,and uses a combination of the theories,the simulation,and experimental methods to analyze the possible degradation mechanisms of optical fiber connectors in three environments:the various temperatures,the industrial and marine atmospheres,and the vibrations.The study quantifies the degree of influence of the three environments on the optical transmission performance of the optic fiber connectors.With regard to the influence of temperature on the optical transmission performance of the optical fiber connectors,the influencing degree of the optical fiber axial deviation and the focus offset on the insertion loss of the connectors were analyzed through optical theories,which was verified by high and low temperature experiments.With regard to the influence of atmospheric environment on the optical transmission performance of optical fiber connectors,the ZEMAX optical simulation was adopted to study the influence of the refractive index,the covering area,and the thickness of pollutants on the insertion loss and return loss of the connectors,which was verified by the acidic salt spray experiments.With regard to the influence of the vibration environment on the optical transmission performance of optical fiber connectors,the finite element simulation was used to analyze the inherent frequency of the connector and the change in insertion loss of the connectors during random vibration was calculated by ZEMAX optical simulation,which was verified by the random vibration experiments.The research results show that under a temperature range of-25℃ to 85℃,the insertion loss of the beam expanding optical fiber connector caused by the axial deviation and the focus offset can be ignored;under an atmospheric pollution environment,as the refractive index of the contaminant attached to the connector lens end face and the area increases a,the insertion loss of the fiber optic connector is non-linearly increasing and the return loss is non-linearly decreasing;the insertion loss of the fiber optic connector reaches the critical threshold when the area of the contaminant is 0.6mm~2,the refractive index is 1.61 and the area of the contaminant is 0.8mm~2,the refractive index is 1.56 0.6dB,when the contaminant area is less than or equal to 0.4mm~2,the insertion loss has no risk of exceeding the threshold value.When the contaminant area is 0.2mm~2,the refractive index is 1.67 and the contaminant area is 0.4mm~2,the refractive index is 1.43,the return loss of the fiber optic connector reaches the minimum threshold of 15dB,when the contaminant area is greater than or equal to 0.6mm~2,the return loss is below the failure threshold of 15dB at the contaminant refractive index of 1.4.The first six natural frequencies of the optical fiber connectors are in the range of 0 to 800Hz.In this frequency range,the insertion loss changes little when the connectors are forced to vibrate.Therefore,when the optical fiber connector works in the airborne environment and the fit state of the male and female ends is good,its optical transmission performance will not be affected by temperature,atmospheric corrosion and vibration stress.However,when the mating state of male and female ends is faulty,pollutants generated by atmospheric corrosion will adhere to the end face of the lens,resulting in poor optical transmission performance,and then affect the reliability of the optical fiber connector.The influence degree depends on the refractive index and coverage area.