一种新型的窄线宽光纤滤波器特性的研究

提出了一种用于单纵模光纤激光器的具有较宽的有效自由光谱范围（FSR）的窄线宽滤波器,该滤波器由一个高双折射光纤（HBF）环嵌套于Sagnac环形镜构成。首先从理论上得到了该滤波器的透射率表达式,然后对该滤波器的特性进行了数值分析。研究结果表明：由于分别沿着HBF的快慢轴运行的光之间会产生游标效应,从而可以获得具有较大的有效FSR的窄带透射峰。当HBF环的无源损耗得到适当补偿后,边峰抑制比能达到6 dB,且该窄线宽滤波器的这些特性与输入光的偏振态无关。在此基础上设计了一种1 053 nm光信号的窄线宽光纤滤波器。

Study on the characteristics of a novel optical narrow-linewidth filter

An optical narrow-linewidth filter with greatly enhanced free spectral range（FSR） is theoretically proposed for employment in single-longitudinal-mode（SLM） fiber lasers.It is of simple construction based on Sagnac loop mirror which contains a high birefringence fiber（HBF） ring and a polarization controller in the interference beam.The transmissivity of the optical narrow-linewidth filter is derived,and the characteristics of the filter are studied numerically.The results show that narrowband transmission peaks with large effective FSR can be obtained due to the intrinsic vernier effect between orthogonally polarized lights travelling along the two primary axes in the HBF.Moreover,when the passive loss of the HBF ring is properly compensated,the side transmission suppression ratio can attain as high as 6dB.These special properties are independent of the polarization state of the input signal.Based on this,a special linewidth filter for 1053nm optical signal is devised.