LAUSR

A micro-size optical sensor for simultaneous detection of dual-point seawater temperature based on microfiber double knot resonators (MDKRs) is demonstrated in this paper. To obtain the optimal sensor parameters, the sensing mechanism and spectral characteristics of MDKRs in seawater are investigated theoretically and experimentally. Results show that the MDKRs with short period spectra is more suitable for the simultaneous detection of dual-point seawater temperature, due that it has a long wavelength range and is easy to distinguish resonant wavelengths of two microfiber knot resonators (MKRs). The sensitivities of the cascaded MKRs are −13.86 pm/°C and −5.6 pm/°C, respectively, achieving independent and simultaneous seawater temperature sensing. The sensor proposed here can meet the actual demands of mesoscale ocean phenomena and micro-region detection in seawater, and offer references for developing simple and convenient optical method in ocean detection and other practical application.