Frequency Modulated Continuous Wave System for Optical Fiber Intensity Sensors With Optical Amplification

Abstract

We report on the use of erbium doped fiber (EDF) amplification to enhance a frequency modulated continuous wave (FMCW) technique for referencing optical intensity sensors located between two Bragg grating structures. The experiment combines the concept of FMCW with the spectrally selective mirror properties of Bragg gratings to interrogate with referencing properties intensity based sensors. The interrogation system without amplification yields a sensor resolution of around 0.078 dB. When the EDF amplifier is introduced into the experimental set up, the sensor sensitivity does not change, but the signal-to-noise ratio is improved, resulting into an enhanced resolution of 0.025 dB. We also obtain a remote sensing operation at a location of 50 km, showing the feasibility of this configuration to be used as a remote sensing application.

Remote Interrogation of WDM Fiber-Optic Intensity Sensors Deploying Delay Lines in the Virtual Domain

“…is considered. A better sensor resolution of 0.025 dB but in the same order of magnitude was obtained in the work reported in [16], where erbium doped fiber (EDF) amplification was used to enhance a frequency modulated continuous wave (FMCW) technique for referencing optical intensity sensors. Nevertheless, since the number of samples and the total sampling time provided by the DAQ board is the same, for a lower modulation frequency a better measurand resolution is expected.…”

Optimization of the frequency-modulated continuous wave technique for referencing and multiplexing intensity-based fiber optic sensors

“…This work explores the combination of the sub-carrier FMCW technique with the mirror spectral selectivity of fiber Bragg gratings (FBG) to achieve multiplexing and referenced interrogation of intensity-based optical fiber sensors. Some preliminary validations of this technique have been previously reported by the authors [18][19][20]. Here, the fundamental operation of this technique is described in detail and then experimental results are presented that demonstrate its effectiveness.…”