Sucrose concentration detector based on a binary photonic crystal with a defect layer and two nanocomposite layers

The concentration of sucrose in an aqueous solution has a wide range of applications in pharmaceuticals, such as protein and food preservation. In this work, we propose a binary Si/SiO2 photonic crystal with a defect layer and two nanocomposite layers for the detection of sucrose concentration in an aqueous solution. The transfer matrix method is employed to analyze the proposed structure. Transmission, reflection and absorption spectra are plotted and studied. The defect mode arising as a result of the breakdown of the photonic crystal periodicity by the defect and the nanocomposite layers is also investigated. Many interesting features have been observed such as the transmission peak being sharply reduced with the increase of the nanocomposite layer thickness and the angle of incidence. The sensitivity of the photonic crystal can be enhanced by increasing the defect layer thickness and the incidence angle. It can be further improved by limiting the nanocomposite layer thickness to 5 nm. The proposed structure exhibits excellent tuning with any change in the sucrose concentration and it shows high sensitivity of about 893 nm/RIU. Therefore, it can be used as an efficient optical sensor device with enhanced sensitivity due to the nanocomposite layers.