Determination of temperature and strain by a compact optical fiber Mach-Zehnder interferometer (MZI) composed of a single-mode fiber (SMF), seven core fiber (SCF), and multimode fiber (MMF) with a fiber Bragg grating (FBG)

Abstract

A compact optical fiber Mach-Zehnder interferometer (MZI) sensor is reported for temperature and strain. The MZI sensor consists of a single-mode fiber (SMF), a seven core fiber (SCF) and a multimode fiber (MMF) with a fiber Bragg grating (FBG). The intensity distribution of the sensor is calculated by the beam propagation method. The light is coupled from the lead-in SMF into the SCF through the MMF. The highest transmission efficiency was obtained when the length of MMF is 2 mm with a diameter of 105 μm. The temperature sensitivity is up to 55.06 pm/°C from 130 °C to 250 °C, while the maximum extinction ratio was 27.4 dB. The measurements were divided into two intervals to address cross coupling to provide sensitive temperature and strain measurements.

Keywords:

• Fiber optic sensor
• Mach-Zehnder interferometer (MZI)
• seven core fiber (SCF)
• multimode fiber (MMF)
• fiber Bragg grating (FBG)
• temperature and strain

Additional information

Funding

This work is supported by the Open Research Project of Beijing Key Laboratory in 2019 (GDKF2019003), the Key Projects of the National Natural Science Foundation of China (51535002), and the 111 Project (D17021).