Open AccessMeasurement of Brillouin gain spectrum with dual‐frequency laser for optical fibre sensor
Author(s) -
Salhi M.,
Kemlin V.,
Faci S.,
Baili G.,
Khadour A.,
Mostarshedi S.,
Billabert A.L.
Publication year - 2020
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
ISSN - 1350-911X
DOI - 10.1049/el.2019.4101
Subject(s) - brillouin zone , optics , brillouin scattering , laser , photodetection , materials science , optical fiber , physics , photodetector
In this Letter, the authors present a first measurement of Brillouin gain spectrum with dual‐frequency solid‐state laser. This allows a coherent detection of the Brillouin backscattered spectrum in a frequency range below the hundreds of MHz by fine‐tuning of the difference between the two cross‐polarised fields emitted by the laser. The photodetection at low‐frequency benefits from the balanced detection technique where high dynamic range measurements are largely available. The narrow line‐width of the cross‐polarised field permits also the direct measurement of the Brillouin spectrum line‐width. The system is demonstrated by measuring the Brillouin frequency shift with temperature when standard single‐mode fibre‐28 (SMF‐28) and large effective area fibre (LEAF) are fully heated. This gives temperature coefficients close to theoretical expectations with values of 1.16 MHz/°C for SMF‐28 and 1.15 MHz/°C for LEAF.