侧边抛磨多模光纤中光功率传输特性研究

Investigations of optical power transmitting characteristics in sidepolished multimode fiber

侧边抛磨多模光纤(SPMMF)与侧边抛磨单模光纤(SPSMF)相比,具有工艺上容易实现的优势。为了研制SPMMF传感器,分析SPMMF中光功率传输特性,首先利用有限差分光束传输法(BPM)模拟计算了不同剩余半径SPMMF中的光强、模场分布以及光纤中传输光功率与抛磨区覆盖材料折射率的关系,并进行了实验验证。实验结果与模拟结果相互吻合:当抛磨区覆盖材料折射率小于1.440时,光功率透过率接近在空气中的透过率;当覆盖材料的折射率逐渐增大到1.458时,光功率透过率减小到最小值,且最小值不小于0.001;当覆盖材料的折射率大于1.458时,光功率透过率由最小值逐渐增大,最终维持在一个相对稳定的值;不同剩余半径的SPMMF中的传输光功率透过率不同,剩余半径越小,SPMMF中传输光功率透过率越小。

So SPMMF is easier to be implimented techanically compared with the side polished singlemode fiber. To develop side polished multimode fiber （SPMMF） sensor,the optical power transmitting charac- teristics in SPMMF are analyze＆ First we utilize BPM to simulate and calculate the distribution of light intensity and mode field in SPMMF with different remaining radii, and the relation between the transmit- ted light power in fiber and the index of refraction of cover material in polished area is derived as well. furthermore,we demonstrate our conclution with experiment. The results show that when the index of refraction of cover material in polished area is smaller than 1.44, the transmittance of light power in fiber is close to the transmittance in air~ When the index of refraction of cover material in polished area in- creases to 1. 458, the transmittance decreases to the minimum, and the minimum is not less than 0. 001; When the index of refraction of cover material in polished area is lager than 1. 458, the transmittance in- creases slowly and remains at a relatively stable value. The transmittance of the transmitted light power in SPMF will be affected by remaining radius. We conclute that the transmittance of the transmitted light power in SPMF is smaller as the remaining radius is smaller.