利用模式耦合理论和有限元求解方法，研究了基于选择填充光子晶体光纤(PCF)的耦合器对弯曲的响应。引入等效折射率(RI)，将弯曲波导简化为直波导，仿真确定耦合波长并分析器件弯曲传感性能。研究表明，耦合波长的移动与弯曲曲率呈线性关系，并指示弯曲方向；耦合波长由填充液体折射率和空气孔直径决定；弯曲灵敏度取决于填充孔与纤芯距离。利用此规律，设计了基于选择填充PCF的二维弯曲矢量传感器。在PCF截面上选择相互正交的2个空气孔，分别填充不同折射率液体，2条液体波导各自与纤芯形成耦合器，监测2个耦合波长变化即可求解器件的弯曲曲率及在二维空间中的弯曲方向。该传感器具有良好的设计柔性与制备可控性，具有良好的应用前景。

With mode coupling theory and finite element solving method, a photonic crystal fiber (PCF) coupler basing on selective infiltration and its response to bending are investigated. The bended coupler is treated as a straight waveguide by introducing an equivalent refractive index (RI). The coupling wavelength is simulated and the bend sensing characters are analyzed. The coupling wavelength shift has linear response to bending curvature with directional indication; the coupling wavelength is decided by the RI of infiltrated liquid and the diameter of air-holes; while the bending sensitivity is affected by the distance between the infiltrated hole and the fiber core. With these characters, a two-dimensional bending vector sensor is designed based on selectively infiltrated PCF. Two orthogonal air-holes on the cross-section of the PCF are selected to be filled with different RI liquids. The two liquid waveguides couple with fiber coreseparately. The shift of two coupling wavelengths indicates the bending curvature in two orthogonal directions. The bending curvature and two- dimensional direction can be solved simultaneously by inspecting the shift of two coupling wavelengths. The flexible design and controllable fabrication of the sensor has been demonstrated and a promising sensing application could be seen.