Simultaneous Measurement of Seawater Temperature and Salinity Based on Microfiber MZ Interferometer With a Knot Resonator

It is significant to develop new methods for temperature and salinity measurement in seawater since they are two important parameters in physical oceanography application. In this paper, a new approach for simultaneous measurement of temperature and salinity in seawater based on microfiber Mach-Zehnder (MZ) interferometer with a knot resonator is proposed. The typical transmission spectra show the combined effect of MZ interference and knot resonance. When the temperature and salinity change, both the interference dip and the resonance dip shift linearly. Based on the linear relation, the measurement matrix is established, and the temperature and salinity of seawater sample can be obtained simultaneously by collecting the transmission spectra. The hybrid structure demonstrated here shows advantages of high sensitivity and good accuracy, which may have great potential for temperature and salinity measurement in ocean and other liquid surroundings.