Multimodal Interferometer Based on a Suspended Core Fiber for Simultaneous Measurement of Physical Parameters

In this study, a multimodal interferometer based on a suspended core photonic crystal fiber (PCF) for simultaneous strain and temperature measurements is proposed. The structure is also employed for angle measurements. The sensor comprises a 3-mm-suspended core PCF between SMFs and is based on the combination of two multimodal interferences with different frequency fringe patterns. The interferometric patterns show different sensitivity responses to strain and temperature. Through a low-pass frequency filtering of the detected spectrum, the wavelength shift of the two patterns can be measured allowing the discrimination of strain and temperature effects with resolutions of 0.45 °C and 4.02 με, respectively. The sensor is also characterized for angle measurements showing a maximum sensitivity of 9.17 pm/° in the range from 0° to 90°. It is demonstrated that with this sensing structure is possible to obtain simultaneous measurement of bend angle and temperature with resolutions of 1.69 ° and 0.92 °C, respectively.