G.657 B3光纤截止波长测试方法的探讨

Discussion on the Cut-off Wavelength Test Method for G.657 B3 Optical Fiber

截止波长是单模光纤中仅有基模传输的最短波长。G.657光纤是新型的接入网用弯曲损耗不敏感单模光纤,其耐弯曲性能优越,因此采用常规弯曲参考法和多模参考法方法很难测得其准确的截止波长。根据相关IEC标准和国家标准,结合G.657B3光纤的特性,改进设计了熔接引导光纤弯曲参考法、增加被测光纤长度多模参考法、弯曲被测光纤弯曲参考法三种G.657B3光纤截止波长的测试方法,以期通过熔接引导光纤、增加被测光纤长度和改变被测光纤弯曲半径及绕圈圈数方式滤去高阶模。相关研究表明,采用增加被测光纤长度多模参考法可较为准确、可靠地测得G.657B3光纤截止波长,以及被测光纤长度宜为22m,最短不低于12m。

Cut-off wavelength is the shortest wavelength in a single-mode optical fiber which only has the fundamental mode transmission. As a new bending-loss insensitive single-mode optical fiber for access network, G.657 optical fiber has a good bending resistance performance. Thus it is difficult to get its accurate cut-off wavelength by normal bending reference test method and muhimode reference test method. According to relevant IEC standard and national standard and combined with the characteristics of G.657 B3 optical fiber, three improved test methods for cut-off wavelength of the G.657 B3 optical fiber include the fusion splicing guiding optical fiber bending reference test method, the increasing tested optical fiber length multimode reference test method and the bending tested optical fiber bending reference method are designed. The above three test methods remove the high-order mode by fusion splicing guiding optical fiber, increasing tested optical fiber length and changing tested optical fiber bending radius and winding number. The research results indicate that the increasing tested optical fiber length muhimode reference test method can get more accurate and reliable data of cut-off wavelength of G.657 B3 optical fiber, and the tested optical fiber length is recommended 22 m and shouldn＇t shorter than 12 m.