光纤旋转连接器因其具有传输带宽大、电磁兼容良好、体积小、寿命长等优点，有逐渐取代传统电滑环进行相对旋转平台间信息传输的趋势。提出一种利用大模场光子晶体光纤直接耦合的新型光纤旋转连接器的设计方案，耦合理论分析表明其不仅满足低插入损耗，而且具有结构简单、体积小、加工和装配精度要求相对较低等优点。大模场光子晶体光纤的无截止波长单模传输和低非线性传输特性使它能更有效地与WDM技术相结合提高传输容量，具有更广阔的应用。

Fiber optic rotary joint is used for signal transmission between stationary platform and rotary platform because of its advantages of high bandwidth,electromagnetic compatibility,small size,etc. A novel design of fiber optic rotary joint based on direct coupling technology of large mode area photonic crystal fiber(LMA-PCF)is designed. The analysis results of coupling theory indicate that this design provides low insertion loss and decrease requirement of accuracy of machining and assembly. Because LMA-PCF possesses the properties of non-cut-off-wavelength single-mode and lower non-linear transmission,the PCF optic rotary joint could be effectively associated with technology of WDM to increase transmission capacity.