熔融光纤器件熔锥区的形貌和微观结构研究

Research on Morphology and Microstructure in the Taper Region of Fused Fiber Devices

熔锥型光纤器件的光学性能由熔锥区的微观结构和形貌决定,而微观结构和形貌又由工艺条件决定。为了分析工艺条件对微观结构与形貌的影响机理及规律,以不同拉锥速度制作的耦合器为测试样,用显微红外光谱仪测试了其熔区和锥区的波数,用扫描电子显微镜观察了其相应点的表面形貌。经多次实验发现:在1100 cm-1和810 cm-1左右有两个明显的特征峰;1100 cm-1特征峰在锥区的波数最高,熔区次之,裸光纤最小;且随着拉锥速度的增大,1100 cm-1特征峰移向高波数。在光纤耦合器的锥区,存在微裂纹,随着拉锥速度增大,微裂纹越明显;在光纤耦合器的熔区,光纤表面析出了微小晶粒,且拉锥速度越小,晶粒越粗大。只有在适当的拉锥速度下(这里为150μm/s),熔区和锥区的结构与裸光纤的微观结构接近,且缺陷最少,才能获得较高质量的光纤耦合器。

The optical performance of the fused-taper fiber device is determined by microstructure and morphology of the fused taper region, which are determined by technological conditions. In order to find out the effect of technological conditions on microstructure and morphology, experiment has been carried out. Taking the couplers manufactured at different drawing velocities as samples, the wave number of the fused regions and taper regions is measured with micro infrared spectrometer, and the morphology of the same point is recorded with scanning electron microscope （SEM）. It is discovered that there are two characteristic peaks： one is at about 1100 cm^-1 , the other at about 810 cm^-1 The wave number of the former peak is highest at the taper region, the one at the fused region followed, and the one of bare fiber lowest. The 1100 cm^-1 characteristic peak shifts to higher wave number while the drawing velocity increases. In the taper region, cracks are discovered. And the cracks are more obvious while drawing velocity increases. In the fused region, there appear crystallines on the surface of the coupler, and the crystalline grain becomes smaller while the drawing velocity increases. A higher quality of coupler cannot be obtained until less change of the microstructure and less defects under the proper drawing velocity （here is 150μm/s） are realized.