Silicon based Double Fano resonances photonic integrated gas sensor

Abstract The telecommunication wavelengths play a crucial role in the development of photonic integrated circuit (PIC). The absorption fingerprints of many gases lie within these spectral ranges, offering the potential to create miniaturized gas sensor for (PIC). In this work, we present novel double Fano resonances within the telecommunication wavelength range, based on silicon metasurface for selective gas sensing applications. Our proposed design comprises periodically coupled nanodisk and nano-bar resonators mounted on a quartz substrate. We show that the Fano resonances can be precisely tuned across the wavelength range from (𝜆=1.52𝜇m) to (𝜆=1.7𝜇m) by adjusting various geometrical parameters. Furthermore, we optimize the sensor for double detection of carbon monoxide (CO), with an absorption fingerprint at ~ 1.566 𝜇m, and nitrous oxide (N2O), with an absorption fingerprint at ~ 1.67𝜇m. The sensor exhibits exceptional refractometric sensitivity to CO of 1,735 nm/RIU with an outstanding FOM of 11,570. In addition, the sensor shows a sensitivity to N2O of 194 accompanied by a FOM of 510. The structure reveals absorption losses of 7% for CO and 3% for N2O. The outstanding FOM and absorption losses provide selectivity for the sensing material. Our proposed design holds significant promise for the development of highly sensitive double detection refractometric photonic integrated gas sensor.