给出了保偏光子晶体光纤（PM-PCF）模场的计算模型，搭建了基于近场光斑成像法的PM-PCF 非圆模场在线测量装置，采用红外成像系统实现了模场参数的绝对测量。在此基础上，研究了放电对PM-PCF 模场的微调作用，结合仿真计算，获得模场参数变化规律。建立了PM-PCF与传统保偏光纤的耦合损耗计算模型，确定了低损耗耦合条件，并进行了熔接实验验证，实现了PM-PCF与传统保偏光纤的低损耗熔接。

The model for characterizing the mode field of polarization-maintaining photonic crystal fiber (PMPCF) is proposed. The on-line mode field testing setup for PM-PCF is established based on the near field spot imaging method and the absolute measurement of mode field parameters is achieved with an infrared camera system. The effect of discharge on the PM- PCF mode field redress is investigated and the evolutions of mode field parameters are also obtained by numerical simulations. The calculation model of the splicing loss between PM- PCF and conventional polarization maintaining fiber is derived, and the low loss splicing condition is also determined and experimentally verified. The result demonstrates that the loss splicing between PM-PCF and conventional polarization maintaining fibers is successfully realized.