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

Naim Ben Ali,Mounir Kanzari,Haitham Alsaif,Vigneswaran Dhasarathan,Youssef Trabelsi,Muhammad Tajammal Chughtai

doi:10.3390/coatings11060713

Abstract

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 P 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 (Q-factor) of the resonance peaks depends on the number (P) of layers. After that, the thickness of the layers is deformed by changing the deformation degree (h). The parameters P and h are optimized to get the maximal Q-factor with the minimal number of layers and structure thickness. The best sensitivity SS of the proposed salinity sensor is 558.82 nm/RFIU with a detection limit of 0.0034 RFIU. In addition, the best sensitivity ST of the designed temperature sensor is 600 nm/RFIU with a detection limit of 0.0005 RFIU.

Highlights

The health of living organisms such as humans, plants and animals depends on the quality of water [1]
The studied photonic structure is constructed by alternating TiO2 and fused silica (F) as two elementary layers, and at the middle of the structure we find a cavity containing seawater (S), of which we want to measure salinity and temperature
It is clear that the peak intensity is still upper 0.8 for P varying from 8 to 52 layers and from 62 layers, the transmittance peak disappears

Summary

Introduction

The health of living organisms such as humans, plants and animals depends on the quality of water (like the absence of bacteria and a low level of mineral salts) [1]. The emergence of photonic structures proposed by John [5] and by Yablonovitch [6] makes it possible to eliminate some problems of older electronic devices such as the Joule effect [4] These structures known as photonic band gap materials are made by alternating two or more different materials. Photonic structures [17] represent a serious opportunity for researchers to study and improve their properties to be suitable for sensing applications [18] They can be used for salinity sensing [1,19], for D-glucose sensing [20], for temperature [15,19] and pressure sensing [15], for humidity sensing [21], for hemoglobin sensing [22] and for cancer cell detection [23]. In previous research papers 1D and 2D photonic structures were proposed to measure salinity and water temperature [1,19]

Photonic Structure Design

Results and Discussion

Salinity Sensing

Temperature Sensing