Fibre Optic Monitoring (FOM) - Working Principle

Among the different sensing and multiplexing techniques available, DBE TECHNOLOGY's sensor development focuses on Fibre Bragg Grating technology along with corresponding multiplexing technique.

Fibre Bragg Grating, (FBGs) are diffracting elements printed in the Germanium-doped core of an optical fibre. FBGs consist in a periodical modulation of the core refractive index along a short length. They behave like selective filters which reflect in the fibre core the spectral components (lamba) of a propagating packet according to the Bragg relation lamba=2 n*^ , with n being the core mean reflective index and ^ the FBG step or the spatial peroid of the refractive index modulation.

If the temperature varies, n is accordingly altered by the thermo-optic effect. If the FBG is strained along the fibre axis, ^ is changed. As a result, the FBG (or Bragg) wavelength is shifted, which is a measure of the parameter under observation.

FOM - Working Principle Graph


Fibre Optic Monitoring (FOM)

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.
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