Development of Magnetooptical Plastic Fiber

本文报道了一种利用Bi-YIG纳米颗粒分散的磁光活性光纤的电流传感器。采用共沉淀法和热处理法制备了Bi-YIG纳米粒子。MMA用于基质，PMMA用于基质中的分散剂。随着Bi-YIG颗粒在光纤中体积分数的增加，光纤的光吸收系数和磁光特性（如饱和法拉第旋转和Veldet常数）均增加。在优化的光纤长度和体积分数条件下，作为电流传感器最重要参数的Veldet常数是稀土掺杂玻璃的10倍。光源的最佳波长为520 nm。Bi-YIG颗粒的分散性提高了磁光性能。尝试了两种用于共沉淀的添加剂以改善研磨过程中的研磨性，换句话说，改善可研磨性。一种是NaOH溶液，另一种是硫酸铵。加入NaOH溶液降低了结晶温度，导致研磨过程后的颗粒更小。TEM观察表明，在使用NaOH和硫酸铵的共沉淀的情况下，尺寸为20-40 nm的Bi-YIG颗粒分散良好，而在常规方法的情况下存在凝聚。折射率的差异导致吸收系数的减小和法拉第旋转的增加。优化后的品质因数最大值达到4.8，是常规优化的2倍或更高。

This report describes a current sensor using Bi-YIG nanoparticle-dispersed optical prastic fiber with magnetooptical activity. Bi-YIG nanoparticles were prepared by coprecipitation followed by heat treatment. MMA was used for the matrix and PMMA was used for a dispersion agent in the matrix. Both optical absorption coefficient and magnetooptical properties such as saturation Faraday rotation and Veldet constant increased with increasing the volume fraction of the Bi-YIG particle in the fiber. Under the optimized conditions of the fiber length and the volume fraction the Veldet constant, which is the most important parameter for the current sensor, was 10 times as high as rare-earth doped glass. The most preferable wavelength of the optical source was 520 nm.Dispersability of the Bi-YIG particles improves the magnetooptical properties. Two additives for the coprecipitation were tried to improve the dispersibility, in other words, to improve grindability during the milling process. One was NaOH solution, and the other was ammonium sulfate. Adding NaOH solution decreased the crystallization temperature, leading to smaller particles after the milling process. TEM observation revealed that the Bi-YIG particles with the size of 20-40 nm were well dispersed in the case of the coprecipitation using NaOH and ammonium sulfate while coagulations exist in the case of the conventional process. The difference in the dispersibility led to the reduction in the absorption coefficient and the increase in the Faraday rotation. The maximum value of figure of merit reached 4.8, which is twice or higher than the conventional one.