High Sensitivity to Salinity-Temperature Using One-Dimensional Deformed Photonic Crystal

• Main Authors: Naim Ben Ali, Haitham Alsaif, Youssef Trabelsi, Muhammad Tajammal Chughtai, Vigneswaran Dhasarathan, Mounir Kanzari
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Coatings
• Subjects: photonic crystal; salinity sensor; temperature sensor; sensitivity; deformation; quality factor
• Online Access: https://www.mdpi.com/2079-6412/11/6/713

This paper aims to theoretically study the concept of a photonic salinity and temperature sensor according to a deformed one-dimensional photonic structure. The fundamental capability of the proposed sensor is studied. Simultaneously we search to optimize the thickness of the structure and to get the maximum salinity and temperature sensitivity. The structure is constructed by alternating layers of TiO₂ and fused-silica <i>P</i> times. In the middle of the structure, a cavity containing seawater is inserted to measure its salinity and temperature. The transfer matrix method (TMM) is used to simulate the wave-transmittance spectra. It is shown that the quality factor (<i>Q</i>-factor) of the resonance peaks depends on the number (<i>P</i>) of layers. After that, the thickness of the layers is deformed by changing the deformation degree (h). The parameters <i>P</i> and <i>h</i> are optimized to get the maximal <i>Q</i>-factor with the minimal number of layers and structure thickness. The best sensitivity <i>S_S</i> of the proposed salinity sensor is 558.82 nm/RFIU with a detection limit of 0.0034 RFIU. In addition, the best sensitivity <i>S_T</i> of the designed temperature sensor is 600 nm/RFIU with a detection limit of 0.0005 RFIU.