Simultaneous measurement of axial strain and temperature based on a twin-core single-hole fiber with the optical Vernier effect

An ultrasensitive optical fiber sensor based on the optical Vernier effect is proposed for the simultaneous measurement of axial strain and temperature. The sensor structure comprises two cascaded Mach-Zehnder interferometers (MZIs) with different free space ranges. The single MZI is built up by fusion splicing a segment of similar to 3 mm twin-core single-hole fiber (TCSHF) between two pieces of similar to 5 mm none core fibers (NCF). When acting separately, each MZI can respond linearly to the axial strain change with a sensitivity of similar to 0.6 pm/mu e and temperature with a sensitivity of similar to 34 pm/degrees C. When the two MZIs are cascaded in series, the sensitivities are amplified about 30 times because of the optical Vernier effect. Experimental results demonstrate that the cascaded structure exhibits a high axial strain sensitivity of similar to 17 pm/mu e in the range of 0 to 2000 mu e and temperature sensitivity of similar to 1.16 nm/degrees C in the range of 30 to 70 degrees C. Moreover, the cascaded structure can simultaneously measure the axial strain and temperature change in the acceptable error ranges. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

An ultrasensitive optical fiber sensor based on the optical Vernier effect is proposed for the simultaneous measurement of axial strain and temperature. The sensor structure consists of two cascaded Mach-Zehnder interferometers (MZIs) with different free space ranges. The sensitivities of the sensor are significantly amplified by approximately 30 times when the two MZIs are cascaded in series due to the optical Vernier effect. The experimental results demonstrate that the cascaded structure exhibits high sensitivities for axial strain (approximately 17 pm/με) and temperature (approximately 1.16 nm/℃) within their respective measurement ranges, while simultaneously measuring both parameters within acceptable error ranges.