Abstract

Breath sensing is an effective tool for health monitoring. Previously, high-mesa waveguide structures have been proposed by our group for realizing a compact breath-sensing photonic circuit. By using the doped ${{\rm SiO}_2}$ as the waveguide core, 50% concentration ${{\rm CO}_2}$ has been detected. One issue of preventing parts per million (ppm)-order detection is the low portion of evanescent light (${\Gamma _{\rm air}} = {2.2}\%$) in the doped ${{\rm SiO}_2}$ waveguides. In order to realize low propagation loss $\alpha$ and high ${\Gamma _{\rm air}}$ simultaneously, thin silicon (Si) waveguides with a ${\Gamma _{\rm air}}$ as high as 37.6% have been proposed and fabricated in this work. A thermal oxidation technique was applied to further reduce $\alpha$, so that $\alpha$ was decreased from 1.45 to 0.84 and 0.29 to 0.2 dB/cm for the 0.5 and 3-µm-wide waveguide, respectively. According to our analysis, the significantly decreased $\alpha$ is attributed to recovering the damaged Si core and smoothing the waveguide sidewalls. The high ${\Gamma _{\rm air}}$ and effective loss reduction show a promising potential of applying Si high-mesa waveguides to realize ppm-order sensing.

© 2020 Optical Society of America

Ultra-low stress SiO₂ coatings by ion beam sputtering deposition

Aaron Davenport, Emmett Randel, and Carmen S. Menoni
Appl. Opt. 59(7) 1871-1875 (2020)

Study of low-peak-power highly coherent broadband supercontinuum generation through a dispersion-engineered Si-rich silicon nitride waveguide

M. R. Karim, Nayem Al Kayed, Md Rabiul Hossain, and B. M. A. Rahman
Appl. Opt. 59(20) 5948-5956 (2020)

Design and fabrication of As₂Se₃ chalcogenide waveguides with low optical losses

Zhuodong Fan, Kunlun Yan, Limeng Zhang, Jingshuang Qin, Jinbo Chen, Rongping Wang, and Xiang Shen
Appl. Opt. 59(6) 1564-1568 (2020)

Polarization diversity schemes for gas sensing applications: a comprehensive analysis and optimal design of high-performance S i _1−x G e _x mid-infrared asymmetric rib cross-slot waveguides

Harshvardhan Kumar, Tanisha Bohra, Apoorv Sharma, P. Susthitha Menon, and Agus Muhamad Hatta
J. Opt. Soc. Am. B 40(12) 3246-3254 (2023)

Low loss Si₃N₄–SiO₂ optical waveguides on Si

C. H. Henry, R. F. Kazarinov, H. J. Lee, K. J. Orlowsky, and L. E. Katz
Appl. Opt. 26(13) 2621-2624 (1987)