Abstract

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.

Effects of combined process of reactive ion etching and dynamic chemical etching on UV laser damage resistance and surface quality of fused silica optics

Laixi Sun, Jin Huang, Ting Shao, Xin Ye, Qingzhi Li, Xiaodong Jiang, Weidong Wu, Liming Yang, and Wanguo Zheng
Opt. Express 26(14) 18006-18018 (2018)

Post-processing of fused silica and its effects on damage resistance to nanosecond pulsed UV lasers

Hui Ye, Yaguo Li, Qinghua Zhang, Wei Wang, Zhigang Yuan, Jian Wang, and Qiao Xu
Appl. Opt. 55(11) 3017-3025 (2016)

Effects of deep wet etching in HF/HNO₃ and KOH solutions on the laser damage resistance and surface quality of fused silica optics at 351 nm

Mathilde Pfiffer, Philippe Cormont, Evelyne Fargin, Bruno Bousquet, Marc Dussauze, Sébastien Lambert, and Jérôme Néauport
Opt. Express 25(5) 4607-4620 (2017)

Optical ridge waveguides preserving the thermo-optic features in LiNbO₃ crystals fabricated by combination of proton implantation and selective wet etching

Yang Tan and Feng Chen
Opt. Express 18(11) 11444-11449 (2010)

Fabrication and characterization of microstructures with optical quality surfaces in fused silica glass using femtosecond laser pulses and chemical etching

Yuri Sikorski, Corneliu Rablau, Mark Dugan, Ali A. Said, Philippe Bado, and Lars Guenter Beholz
Appl. Opt. 45(28) 7519-7523 (2006)