In this work, we propose an optical fiber sensor based on a silica capillary section spliced between two sections of single mode fiber. One of the fusion splices is done with a transversal offset, to enable the creation of a Mach-Zehnder interferometer (MZI). Furthermore, the structure, monitored in transmission, also exhibits anti-resonant behavior. This effect is inhibited by submerging the sensor in liquid media, and the MZI becomes dominant. The sensor with a length of 3.75 mm presented a linear response to temperature with a sensitivity of 26.0 pm/°C. Combining this sensor with another with a length of 3.82 mm, in a parallel configuration where both sensors are placed under water, an interferometric pattern with a higher frequency modulated by a lower one is attained, which is produced by the Vernier effect. The sensor, although insensitive to refractive index variations, showed a maximum temperature sensitivity of 2.193 nm/°C, showcasing a magnification factor of 84.3. This sensor may find applications in different fields where an accurate measurement of temperature in liquid media is required, such as chemistry, pharmaceutical, and biological applications.
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