Bertrand Poumellec

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We describe a framework for modeling the writing and erasure of thermally-distributed activated processes that we can specifically apply to UV-induced refractive index change, particularly in fibers. From experimental measurements (isochrons and/or isotherms), this framework allows to find the distribution function of the activation energy by providing only(More)
This paper is dedicated to the lifetime prediction of Type I Fiber Bragg gratings (FBG) and to problems that happen when stabilization (also called passivation) conditions or the industrial conditioning procedure depart from ageing ones (e.g., presence of hydrogen during the passivation process). For the first time, a reliable procedure to certify the(More)
Recently, we showed that femtosecond laser induced " nanogratings " consist of thin regions with a low refractive index (Δn = −0.15), due to the formation of nanoporous silica surrounded by regions with a positive index change. In this paper, we investigate a wide range of laser parameters to achieve very high retardance within a single layer; as much as(More)
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