High-Resolution Seawater Salinity Sensor Based on Temperature Self-Compensating Optical Interferometer

A high-resolution seawater salinity sensor, based on a temperature self-compensating resonator, has been developed, which accommodates simultaneous temperature variations in both the reference and sensing arms. The impact of external temperature fluctuations on the optical components affecting the optical path difference is significantly reduced, and a salinity sensitivity of 145 pm/Practical Salinity Unit (PSU) and a salinity resolution of 0.0003 PSU are achieved. The sensor uses a structure that converts optical rays into spatial light, achieving noncontact measurements which are potentially pivotal for various applications in oceanography and marine studies.