Study On Mechanical Strength And Bending Loss Of Optical Fiber Changing With Different Environments

With the increasing development of optical fiber communication,fiber optics play a more and more important role in all aspects of our lives.In order to ensure the quality of communication,optical fiber cannot be broken under some exerted tensile force,as requires the mechanical strength of optical fiber.Optical fiber may inevitably be bent and consequently generate light loss when it is amounted or used.Therefore,it is necessary to study the rule of change of fiber bending loss with the fiber bending radius,and to find critical bending radius.In order to allow optical fiber to adapt to various environments,the mechanical strength and bending loss of optical fiber need to be measured respectively in different environments.We simulate four kinds of environments:the normal temperature,high temperature and humidity,salt mist and vulcanization.The optical fiber stretching fixture and tensile test system are designed,and the mechanical strength of optical fiber under each of the environments of normal temperature,high temperature and humidity,salt mist and vulcanization was measured and compared.It is found that the fracture strength of optical fiber under each of these extreme conditions is lower than that under normal temperature.The worse the environment is,the more severe the fracture strength drops.The morphology of the fiber section was observed by scanning electron microscope,and the reason for the decline of mechanical strength of optical fibers treated by high temperature and humidity and salt mist environment are explained.Proceeded by high temperature and humidity,salt mist and vulcanization environment,the optical fiber was corroded by the external environment,and created a crack or generated a crack to expand,Thus the fracture strength of the fiber was affected.An X-ray photoelectron spectrometer was used to detect the existence of the element of sulfur in vulcanized fiber.It was proved that after vulcanization,the element of sulfur was penetrated into the interior of the fiber,producing filaments or white dots,which were responsible for the decline of the fiber's mechanical strength.In addition,the bending loss coefficients of optical fibers under the environments of normal temperature,high temperature and humidity,salt mist and vulcanization were tested.By comparison of bending loss between the fiber in normal temperature and in the environments of high temperature and humidity,salt mist and vulcanization,it is found that the bending loss of optical fiber in high temperature and humidity,salt mist and vulcanization environment is larger than that under normal temperature condition.And under the same bending radius,the bending loss is approximately linearly changed with the increase of the number of bending rings.When the fiber bending radius exceeds 15mm,the bending loss coefficient is extremely small.The innovation of this subject is that(1)Tensile testing machine and special fixture for measuring optical fiber mechanical strength are designed.This tester is small in size and light in weight,It is easy to carry and easy to operate.The fixture is compact,holding the optical fiber firmly.(2)The mechanical strength is tested of optical fiber in the environments of high temperature and humidity,salt mist and vulcanization.The section morphology of the fiber was observed by a scanning electron microscope.The influence of vulcanization on the mechanical strength of optical fiber was further determined by X-ray photoelectron spectroscopy analysis.(3)The bending loss coefficients of optical fibers processed by the environment of high temperature and humidity,salt mist and vulcanization were tested.And the influence of different environment on the fiber bending loss and the influence of different bending cycles on the environment.It is found that the curve of fiber bending loss varies with bending radius in different environments,and that the bending loss is approximately linear with the change of bending circle number,when the bending radius is fixed.