氧化硅光波导侧壁角测量精度的提高

Effective method to improve measurement accuracy of sidewall angle of silica optical waveguides

氧化硅波导芯层的侧壁粗糙度和角度是导致器件产生光损耗的主要原因之一。为精确测量沉积包层后氧化硅波导芯层侧壁角,研究了一种利用光学成像显微镜测量波导侧壁角度的方法,并详细分析了引起测量误差的显微物镜放大倍数与成像特征之间的关系。根据理论分析对波导侧壁角度的测量值进行了校正,获得的实验结果与激光共聚焦测量结果相一致。利用该测量方法对10组已沉积包层波导芯层侧壁角度进行了测量并与未沉积包层时激光共聚焦的测量结果进行对比,得出测量精度在±1°以内。该方法为沉积包层后氧化硅波导器件芯层侧壁角度测量提供了一种精确可行的方案。

Optical losses of silica waveguides are mainly caused by the core sidewall angle and roughness of the silica waveguides.In this study,to accurately measure the sidewall angle of an upper-cladded waveguide core,we investigate a method using an optical image microscope.Further,we thoroughly analyze the relationship between the magnification of the microscope objective and the imaging features that cause measurement errors.Then,we compensate the experimental measurement results of the waveguide sidewall angle with the intrinsic systematic errors based on a theoretical analysis,which agree with the values obtained via confocal laser microscopy measurements.Furthermore,by comparing the sidewall angle measurement results of 10 sets of cladded waveguides with the confocal laser microscopy measurements of the waveguides before being cladded,we demonstrate that the measurement error is controlled within±1°.This provides a feasible method to quickly and accurately measure the sidewall angle of the core layer of cladded silica waveguides,i.e.,after deposition of the cladding.