Seeing more clearly: Improving the resolution of ocean salinity measurements using a Fabry-Perot resonant cavity.

• Proposed a method utilizing an optical resonant cavity to measure seawater temperature and salinity, characterized by high resolution and stability. • Achieved precise measurement and feedback of the resonance frequency of the Fabry-Perot cavity through frequency-locking techniques. • Utilized the Fabry-Perot resonant cavity to enhance the resolution of ocean salinity measurements. The research on the ocean has entered a new stage: we are not only satisfied with understanding the surface of the ocean, but also eager to comprehend its deeper laws. This appeal requires sensors to be able to observe the physical parameters of the ocean (temperature, salinity, etc.) in a more precise manner, and the resolution of the sensor is one of the core factors. This paper presents a method for high-resolution measurements of ocean temperature and salinity. By using our carefully designed Fabry-Perot optical resonator, we have achieved a very high resolution. Through experiments, we have verified the resolution performance of the sensor across the full range. When the temperature is 40 °C, the highest temperature resolution is 1.15 × 10−4 °C, and when the salinity is 8.86 PSU, the highest salinity resolution is 1.49 × 10−4 PSU. [ABSTRACT FROM AUTHOR]