Use of Noise-Like pulses in Fiber optic interferometric devices to improve sensitivity of vibration sensor

Abstract

In this work, we present a temporal and spectral study of fiber optic Sagnac interferometer applied in vibration detection systems using noise-like pulses (NLPs), with temporal durations of the order of ns and spectral widths of tens of nm. The laser scheme generates a signal at ~1566 nm, with pulse durations between 189.5 ps to 350 ps, and repetition frequencies of ~956 kHz. The internal behavior of NLPs allows to improve the sensitivity of a fiber optic sensor by automatically adjusting the polarization state in a figure-eight laser (F8L) scheme, which modifies the temporal width of the pulse envelope. The experimental scheme consists of a compact Sagnac Ring (SR) interferometer with a polarization-maintaining fiber, with a pulsed figure-eight mode-locked laser (F8L) as source, and intelligent positioning polarization driver boards controlled by a pattern classification neural network (NN), which allow us to adjust the temporal duration of the pulses for long times, causing an increase in the sensitivity of our SR interferometer. One of the advantages of manufacturing the proposed device is the reduced cost by implementing a standard fiber, as well as its reduced size resulting in a device with dimensions on the order of centimeters, improving the characteristics of previous vibration sensors. Finally, the proposed study allows us to show the advantages of self-tuning lasers through automated control, using it for the precise study and operating regions of interest in multivariable systems.