针对传统周期性气孔结构的微结构光纤光栅 (MOFG)写入过程中的高写入散射问题, 本文提出一种新型的大圆孔式微结构光纤光栅。其特点是用一填充适当折射率流体的大圆孔结构来代替部分周期性小气孔。当光束从外侧写入光栅时, 一方面会避免传统周期性气孔结构带来的高写入散射问题; 另一方面大圆孔也将起到一微透镜作用, 有助于进一步提高光束写入纤芯区域的能量比例。仿真分析结果表明：新型大圆孔式微结构光纤光栅的写入效率可达到传统周期性光子晶体光纤光栅、单模光纤光栅写入效率的 288%和 206%左右。同时本文也提出利用对称角度写入方法来保证光栅写入场的对称性, 从而改善单侧写入造成的写入场分布不均匀问题和写入致双折射问题。

For decreasing the high grating inscription scattering of previous array-hole microstructured Optical Fiber Grating (MOFG), a large circular side-hole microstructured optical fiber grating configuration is proposed and analyzed. In this new configuration, a section of array holes is replaced by one large circular hole that is filled with fluid of proper fluidic index. Simulation shows that, due to immunity of array hole and microlens effect, the grating inscription efficiency of this proposed structure is respectively 288% and 206% times of the conventional array hole microstructured optical fiber grating and Single Model Fiber Grating (SMFG), which shows its potential value in high efficient grating. Moreover, a symmetrical angle inscription method is also proposed to guarantee the symmetry of grating inscription field, which will contribute to improving the flatness of beam energy distribution and the corresponding birefringence in single angle inscription process.