带隙型光子晶体光纤微观弯曲传输损耗特性分析

Experimental Investigation on Microbending Loss Properties in Air-Guiding Photonic Bandgap Fiber

空芯光子晶体光纤由于独特的结构,具有不同于传统光纤在弯曲状态下的光传输特性。对空芯带隙型光子晶体光纤的微观弯曲损耗特性进行研究,利用改进型微弯器使光纤获得不同外力和弯曲条件下的响应,测量其传输谱。实验上分析了波长、压力、微弯振幅和微弯周期等因素对于光纤传输损耗的影响,利用模式理论分析给出了微弯损耗产生的原因。结果表明,带隙型光子晶体光纤的抗微弯能力强,由于表面模式的存在,在1520～1620nm波段内光纤微弯损耗随波长的增加而增大。带隙型光子晶体光纤的弯曲损耗随微弯振幅增大而增大,并且在一定范围内损耗随微弯空间周期的增加而增大,但当微弯周期超过一定的临界值时其损耗随之减小;微弯状态下光纤的表面模式、包层模式与损耗密切相关。

Air-guiding photonic bandgap fibers are developed into application in various areas.Microbending loss properties of fiber play an important role in practical application including optical communications and optical fiber senors.Microbending losses in air-guiding photonic bandgap（PBG）fiber are investigated experimentally.Transmission spectra of PBG fiber subjected to microbending under different pressure and conditions are measured.Various factors which affect the microbending loss,including wavelength,pressure,bending period,and diameter,are analyzed.An analysis of the losses associated with surface modes and mode coupling is presented.The results show that,as the existing of surface modes,spectral losses of PBG fiber increase with the wavelength in the band of 1520~1620 nm.Moreover,within the critical period,transmission loss increases with the microbending period.Additionally,as the diameter of the microbending increases,the fiber is found to be more sensitive to the bending loss.