A heptagonal PCF-based oil sensor to detect fuel adulteration using terahertz spectrum

A heptagonal photonic crystal fiber-based oil sensor is proposed and numerically investigated in this paper in order to detect the adulteration of petrol with kerosene using terahertz (THz) signal. The sensing and guiding properties of this sensor is analyzed by using the Finite Element Method (FEM) technique. The sensor achieved a high relative sensitivity of 96.87% with an extremely low loss of 7.21 × 10−4 cm−1 at optimum frequency and structural conditions which outstripped other existing researches. In addition, the sensor offers a small effective material loss of 0.0072 cm−1 with high numerical aperture and spot size. The four layers circular air holes of heptagonal cladding with a large circular-shaped core are represented in this study which reduces fabrication complexity. This outstanding sensitivity and guiding properties might play a vital role in fuel adulteration identification applications in the near future.