Suspended Silicon-Nitride Rib Waveguide Gas Sensor_data

Suspended waveguide gas sensors are receiving attention due to their high external confinement factors (ECF). In this paper, a suspended silicon-nitride rib waveguide gas sensor with high ECF for a wide working wavelength band is proposed. A systematic and detailed discussion is presented to describe and design a suspended waveguide gas sensor, focusing on performance and design parameters. An optimized silicon-nitride suspended rib waveguide sensor with a length of 1.9 cm exhibits an ECF of 112.006% and a low intrinsic loss of 2.24 dB\/cm at an absorption wavelength of 2.566 \u03bcm. The limit of detection (LoD) for the target Acetylene (C\u2082H\u2082) gas is 5.787 ppm at a minimum detectable signal-to-noise ratio of 10. The densely etched holes in the planar waveguide region of the suspended rib waveguide sensor enable a sensor response time of 1.5 \u03bcs. The manufacturing tolerances of the on-chip sensor were also analyzed, the change in ECF was less than 10% under \u00b110% variations in width, rib height, and thickness. The optimized suspended silicon-nitride rib waveguide gas sensor achieves an ECF of 102.3%\u2013118.4% for a 2\u20137\u03bcm working wavelength range, indicating strong potential for broadband gas detection