消除模间干涉现象的光纤光栅模式转换器

光纤通信技术占据了目前通信传输的主要地位，但基于波分复用技术的单模光纤通信系统目前则面临着严重的信道容量危机，因此基于多模/少模光纤的模分复用技术逐渐得到了人们的重视。模式转换器是模分复用技术中的重要器件之一，而长周期光纤光栅是一种很好的全光纤模式转换器。在利用长周期光纤光栅完成LP01到LP11模式转换的基础上，这种新型的模式转换器利用多模光纤消除了模式间干涉，从而使模式转换的模式纯度更高、稳定性更好，在模式转换效率达到99.5%的同时还可以保证几乎没有模式间干涉现象的产生。同时，这种模式转换器的多种传感特性也良好，其对拉力有着很好的线性灵敏性，可以达到2.83 nm/N和5.66 dB/N，因此此结构在未来的模分复用及传感领域会有重要的作用。

Mode converter based on fiber grating to eliminate intermode interference phenomenon

Optical fiber communication technology has occupied the main position of the current communication transmission. But the single mode optical fiber (SMF) communication system based on wavelength-division-multiplexing (WDM) technology is now facing severe channel capacity crisis. Therefore, mode-division-multiplexing (MDM) technology based on the multimode or few mode fiber (FMF) has got the attention of many researchers. Mode Converter (MC) is one of the most important components in MDM technology, and long period fiber grating (LPFG) is a perfect all-fiber mode converter. The LPFG is used to convert LP01 mode to LP11 mode, and the multimode fiber is also used to eliminate inter-mode interference phonemenon in this mode converter. By using this mode converter, the converted mode has higher purity and better stability. The mode conversion efficiency reached 99.5% and there is no inter-mode interference phenomenon between these two modes. This MC device has good sensing characteristics, and this device has good linear sensitivity of strain, it can reach to 2.83 nm/N and 5.66 dB/N. So it can be concluded that this novel structure has excellent performance and will play an important role in the future application of optical fiber MDM and sensing field.