Scientists have created groundbreaking two-dimensional (2D) photonic crystal (PC) sensors to measure the salt content, or salinity, in water. These sensors use the special light-bending properties of 2D PCs, allowing for very precise and accurate salinity measurements. This new technology is a major leap forward for ocean science.
The researchers carefully adjusted different aspects of the sensors, like the size and spacing of tiny structures within them. They found that the best performance came with specific settings: the half diagonal of the hexagonal shape (R) at 500 nanometers, the distance between the cylinders (D) at 250 nanometers, and the number of periods (N) set to 5. Under these conditions, the sensors showed impressive results: a sensitivity of 525 nm/RIU, a figure of merit (FOM) of 80.7 RIU⁻¹, and a quality factor (Q) of 375.
How do these sensors work? They analyze how light passes through them after saltwater is introduced. The presence of salt creates a specific signal within the light spectrum, and this signal changes depending on the salt concentration. This technology has exciting potential for monitoring the health of our oceans and improving desalination processes, which turn saltwater into drinking water.