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Approach for temperature-insensitive strain measurement using a dual-core As2Se3-PMMA taper.

A temperature-insensitive strain sensor is proposed and demonstrated based on a dual-core As2Se3-polymethyl methacrylate (PMMA) taper. Longitudinal and transverse forces on the As2Se3 cores are induced by thermal expansion/contraction of the PMMA cladding due to an order of magnitude difference between the thermal expansion coefficients of As2Se3 and PMMA. At an optimal PMMA layer thickness, the wavelength shift caused by the thermally induced forces on the refractive index of the dual-core fiber cores counterbalances that caused by the thermally induced fiber length variation leading to temperature-insensitive transmission. Temperature-insensitive strain measurement over a temperature range from 30°C to 40°C is demonstrated in a dual-core As2Se3-PMMA fiber with an As2Se3 core diameter of 0.61 μm and a PMMA cladding diameter of 34.4 μm. Thermally induced forces in hybrid fibers open the path towards the realization of novel sensors and devices that are immune to temperature fluctuations.