Analysis and Suppression of Aliased Noises in Time-Division-Multiplexing Interferometric Fiber-Optic Sensor Array

Abstract

Aliased noises elevate the ultimate noise level of a pulse-triggered time-division-multiplexing (TDM) interferometric fiber-optic sensor array. Here we for the first time present an analytical model of the aliasing factor based on noise power spectral density analysis of the interferometric fiber sensor array. In contrast to the previous reports, the aliasing factor is found not only dependent on the pulse width and the repetition frequency, but also on the rising time of the pulse when matched filters are applied to suppress the noise components out of the main lobe. The model also indicates the explicit scaling rule between the aliasing factor and the number of TDM channels. The model are experimentally validated by measuring the noise floors under different combinations of pulse parameters. Based on the model, an ultra-low noise floor of -114 dB ref rad/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sqrt{\mathbf {Hz}}$</tex-math></inline-formula> (i.e. 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\mu}$</tex-math></inline-formula> rad/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sqrt{\mathbf {Hz}}$</tex-math></inline-formula> ) is achieved and up to 6 interferometric sensors can be multiplexed, which, to the best of knowledge, represents the lowest noise level to date for the TDM interferometric fiber-optic sensor array. Our results reveal the prominent influence of the pulse rising time on the aliased noises and provides a practical approach to suppress noise floor of TDM sensor array.