Wright Joel G, Schmidt Holger, Hawkins Aaron R
Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT, 84602, USA.
School of Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
J Lightwave Technol. 2020 Nov 15;38(22):6280-6285. doi: 10.1109/jlt.2020.3012899. Epub 2020 Jul 29.
Silica waveguides are often etched by reactive ion etch (RIE) processes. These processes can leave residual topography that can increase optical loss. We investigated the relation between optical loss and various RIE etch. A wet etch step meant to remove microstructures was also considered and compared. Ridge waveguides were fabricated in plasma enhanced chemical vapor deposited films by three different RIE processes, each with a different gas composition, pressure setting, and applied power setting. Half of each set of waveguides were also subjected to a hydrofluoric acid (HF) solution. The waveguides were tested for optical transmission via the cutback method. The transmission vs waveguide length measurements were plotted to fit an exponential curve and the optical loss and measurement uncertainty for each waveguide set was calculated. Clear distinctions in optical loss were found between the different RIE processes. The HF treatment also has an effect, significantly reducing optical loss for two processes and increasing it for the third. Of the tested RIE processes, one can be suggested for silica waveguides. It results in the lowest optical loss and coincidently has the fastest etch rate.
二氧化硅波导通常通过反应离子蚀刻（RIE）工艺进行蚀刻。这些工艺会留下残余形貌，从而增加光损耗。我们研究了光损耗与各种RIE蚀刻之间的关系。还考虑并比较了用于去除微结构的湿法蚀刻步骤。通过三种不同的RIE工艺在等离子体增强化学气相沉积膜中制造脊形波导，每种工艺具有不同的气体成分、压力设置和施加功率设置。每组波导中的一半还经过氢氟酸（HF）溶液处理。通过截短法对波导进行光传输测试。绘制传输与波导长度的测量值以拟合指数曲线，并计算每组波导的光损耗和测量不确定度。在不同的RIE工艺之间发现了光损耗的明显差异。HF处理也有影响，对于两种工艺显著降低了光损耗，而对于第三种工艺则增加了光损耗。在测试的RIE工艺中，可以为二氧化硅波导推荐一种工艺。它导致最低的光损耗，并且巧合地具有最快的蚀刻速率。
