High temperature annealing behavior of femtosecond written FBGs in Ge-doped fused silica optical fibers

Alexandre Lerner (1, 2) , Thomas Blanchet (1) , Romain Cotillard (1) , Matilde Sosa (1, 3) , Nicolas Roussel (1) , Géraud Bouwmans (2) , G. Laffont (1)

1 LCFO (CEA, LIST) - Laboratoire Capteurs Fibres Optiques (CEA, LIST)
2 PhLAM - Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523
3 ICMMO - Institut de Chimie Moléculaire et des Matériaux d'Orsay

We investigate the behavior and stability of fiber Bragg gratings written by femtosecond laser pulses in Ge-doped fused silica optical fibers, using both the phase mask and point-by-point techniques, during their annealing at 1200°C for 30 min and subsequent aging at 1000°C during 43 hours. Bragg wavelength drifts and reflected peak amplitude variations were shown to drastically differ depending on the writing scheme and thermal history. Particularly, we show that amplitude decay of point-by-point gratings at 1200°C may be easily mitigated by tuning the writing pulse energy. Future work may be pursued in order to finely unravel the high temperature mechanisms regarding the stability of fs written fiber Bragg gratings used as temperature sensors in order to improve measurement stability and accuracy.

Domains: Optics [physics.optics]; Material chemistry

Alexandre Lerner, Thomas Blanchet, Romain Cotillard, Matilde Sosa, Nicolas Roussel, et al.. High temperature annealing behavior of femtosecond written FBGs in Ge-doped fused silica optical fibers. EWOFS 2023 - European Workshop on Optical Fibre Sensors, May 2023, Mons, Belgium. pp.1264331, ⟨10.1117/12.2678399⟩. ⟨cea-04298736⟩