Mach-Zehnder all-fiber interferometer using two in-series fattened fiber gratings

Abstract

We present an all-fiber Mach-Zehnder interferometer consisting of two consecutive fattened sections of dispersion-shifted fiber that act as in-series long period fiber gratings. The proposed Mach-Zehnder interferometer shows a broad fringe pattern ranging from 1000 to 1500 nm and is stable against changes in temperature and strain. By tapering a section of 5mm in length to 50% diameter between the fattened sections we observe an increased sensitivity to temperature changes. The measured temperature and strain sensitivities were in the range of 9–17 pm/°C and 1.44–2.9 pm/μɛ, respectively.