新型三角芯抗弯曲大模场面积光子晶体光纤

Novel bend-resistant large-mode-area photonic crystal fiber with a triangular-core

提出了一种新型三角芯抗弯曲大模场面积光子晶体光纤.该结构采用单一尺寸的圆形空气孔,降低了制作难度.在波长1.064μm处,在平直状态和弯曲半径为30 cm时,模场面积分别为1386μm2和1153μm2,弯曲带来的模场面积减少量仅为16.85%.当弯曲半径为30 cm时,基模的损耗为0.087 dB/m,二阶模的损耗大于1.5 dB/m,大的损耗差有效保证了光纤单模运转.此外,弯曲半径30 cm时,弯曲方向角扩展至±180,光纤弯曲不再受弯曲方向的限制.所设计的光纤结构具有大模场面积、小的模场面积减少量、低的弯曲损耗以及低的弯曲方向敏感度等优势,为小型化、集成化高功率激光传输及光纤激光器和放大器的研究奠定了基础.

A novel bend-resistant large-mode-area photonic crystal fiber with a triangular-core is proposed in this paper. In this structure, the circle air holes with uniform size are used to reduce the difficulty in fabrication. At a wavelength of 1.064 btm, mode field area of the fundamental mode is 1386 Um2 in a straight state, and it is 1153 btm2 at a bending radius of 30 cm. The decrement of mode field area in a bent state is only 16.85% compared with that in a straight state. When a bending radius is 30 cm, bending loss of the fundamental mode is 0.087 dB/m while bending loss of the second order mode is higher than 1.5 dB/m. The bending loss difference between fundamental mode and second order mode is large enough to ensure that the fiber conforms to the single mode operation conditions. Furthermore, when the fiber is bent with a bending radius of 30 cm, the bending orientation angle can be extended to 180, breaking the limit of the bending orientation. The fiber with large mode area, small decrement in mode field area, low bending loss and low sensitivity of bending orientation makes a great contribution to the miniaturization of high power fiber laser and fiber amplifier.