Space Radiation Effects And Mechanism Of The "Panda" Type Polarization Maintaining Optical Fiber

This paper is based on the space application of fiber optic gyroscope, usingground simulation equipment to study the variation in the electron and protonirradiation conditions made the "Panda" type quartz polarization maintaining fiberinduced loss and the loss mechanism induced by various methods of irradiation onquartz optical fiber is discussed by using a variety of analytical methods.In a certain energy electron and proton irradiation, the irradiation induced loss of"panda" type quartz polarization maintaining fiber increased with the increase ofirradiation fluence exponentially. Change regulation of irradiation induced loss ofquartz fiber relate to types and energy of particles. The values of170keV electron and2.6MeV proton irradiation induced loss, at the same fluence, are higher than1MeVelectron and2.3MeV proton irradiation respectively and the same case that2.6MeVproton is higher than170keV. This result suggests that irradiation induced lossbecomes larger with more energy absorbed by the core.Infrared spectrum show that Si-OH defect in the fiber core is an important cause ofradiation induced loss increase of quartz fiber working wavelength of1310nm. And thefurther analysis suggest that Si-OH is the formation of Si-O and atomic H reaction byirradiation. The source of H comes from two sources, one surface of the irradiatedpolymer coating degradation generated, and then reach the core by diffusion, thesecond is the direct injection of proton. In the proton radiation, more Si-OH is formedin the fiber core, so increase of the fiber loss is more significant than electronirradiation at the same fluence.The quartz fiber exists annealing effect after irradiation, and the highertemperature, the more obvious induced loss recovery. This phenomenon indicates that,Si-OH is not the only mechanism of induced loss increase. There are experimentalstudies have shown that hydrogen can lead to increase fiber loss, but there is no directevidence of hydrogen formed under irradiation conditions in the core. From theanalysis of electron and proton irradiation data, the larger H concentration in fiber core under proton irradiation, more H atoms may be combined to generate hydrogen.Annealing experiments show that the degree of fiber annealing after proton irradiationis significantly greater than electron irradiation, which can be an indirect evidence ofradiation loss of hydrogen absorption mechanism. Besides, by reheating the quartzfiber after annealing, optical radiation induced loss value increases with the increase oftemperature, which is also an mechanism of radiation loss increase.