A photonic crystal based on porous silicon as a chemical sensor for the detection of methanol compound

A one-dimensional binary photonic crystal (BPC) with an inverted symmetry is presented as a methanol sensor. The BPC is assumed to have the structure (Si/SiO2)(N) (SiO2/Si)(N), where N is the number of periods. The silicon herein used is porous and the measurand is assumed to be infiltrated into the porous network of the silicon material and the air inside the void space of the ensemble is replaced by a chemical compound with a higher refractive index. This leads to an enhancement in the effective refractive index of the structure and as a result, a redshift of the Bragg peak is observed. The transmission spectra tuning can accurately determine the type of chemical compound that is present in the silicon pores. The structure, as a chemical sensor for the detection of methanol, is investigated with variable porosity, layer liquid fraction, porous layer thickness, and angle of incidence. These parameters play a key role in the performance of the proposed device. A sensitivity of 1186.1 nm/RIU has been reached with the current sensor which is extremely high. This device can become a milestone for the detection of liquids and gases for industrial or commercial purposes.

Automated summary

This article presents a one-dimensional binary photonic crystal (BPC) as a methanol sensor with inverted symmetry. The BPC structure consists of (Si/SiO2)(N) (SiO2/Si)(N), where N is the number of periods. The porous silicon material is assumed to be infiltrated with the measurand, replacing the air in the void space with a chemical compound of higher refractive index, resulting in a redshift of the Bragg peak. By tuning the transmission spectra, the type of chemical compound in the silicon pores can be accurately determined. The current sensor achieved a sensitivity of 1186.1 nm/RIU, making it highly suitable for industrial or commercial detection of liquids and gases.