Asymmetrical Fiber Mach–Zehnder Interferometer for Simultaneous Measurement of Axial Strain and Temperature

Abstract

An asymmetrical fiber Mach–Zehnder interferometer (aFMZI) consisting of a fiber taper and a lateral-shifted junction is proposed and demonstrated to realize simultaneous measurement of axial strain and temperature. The interferometer exhibits different environmental sensitivities for different device architectures. If the taper and the lateral-shifted junction locate spatially close (15 mm), the experimental results would indicate temperature sensitivities of 60.4 and 63.9 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{pm}/^{\circ}\hbox{C}$ </tex></formula> (redshift) and axial strain sensitivities of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 1.47 and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-2.71\ \hbox{pm}/\mu\varepsilon$</tex></formula> (blueshift) at the higher and lower interference orders <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$m_{1}$</tex></formula> (49) and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$m_{2}$</tex></formula> (48), respectively, for the taper–junction interferometer. The junction–taper interferometer has temperature sensitivities of 60.1 and 63.3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{pm}/^{\circ}\hbox{C}$</tex></formula> (redshifts) and axial strain sensitivities of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 1.51 and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX"> $-2.75\ \hbox{pm}/\mu\varepsilon$</tex></formula> (blueshifts) at the interference orders <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$m_{1}$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$m_{2}$</tex> </formula> , respectively.