Novel Ge1-xSix-on-Al2O3-Based Rib Optical Waveguide Mid-IR Sensors on SiO2 Platform

In this letter, we present the first proof of Ge1-xSix-on-Al2O3-based novel rib optical waveguide (WG) for N2O and CO gas detection at 4.5 and 4.67 mu m, respectively. We optimize the rib WG structure using theoretical models to achieve high sensitivity, minimal detectable gas concentration, and low propagation loss. The device's sensitivity and minimal detectable concentration of N2O and CO at lambda = 4.5 and 4.67 mu m, respectively, are excellent. The sensitivity and minimal detectable value (C-min) for N2O (CO) for the optimized device structure are 1.75 x10(-5) ppm(-1) (6.8 x10(-6) ppm(-1)), and 18.93 ppm (14.97 ppm), respectively. The C-min value demonstrate a significant improvement compared with previously reported findings and international standards. These findings demonstrate that Ge1-xSix platforms pave the way for the development of high-performance, compact optical WGs for MIR applications.