Bragg wavelength spectral interrogation device

Bragg wavelength spectral interrogation device, having:

• at least one optical source designed to emit a light signal,
• at least one measurement optical fibre comprising a series of successive Bragg gratings designed to reflect the light signal in different wavelength bands,
• at least one reflective optical fibre comprising a total reflection element,
• at least one wavelength detector, and
• at least one optical switch designed to switch the passage of the light signal between said at least one optical source, said at least one measurement optical fibre, said at least one reflective optical fibre, and said at least one detector according to a sequence of three operating modes comprising a first mode, known as start-up mode, in which the light signal emitted by a given optical source is guided from said optical source to a corresponding measurement optical fibre, a second mode, known as measurement mode, in which said light signal is guided to make a predetermined number of return trips in a line formed by a coupling between said measurement optical fibre and a corresponding reflective optical fibre, thus generating a predetermined delay between the successive Bragg gratings, and a third mode, known as detection mode, in which said light signal is guided to a corresponding detector which is designed to successively measure the wavelength bands associated with the Bragg gratings comprised in said measurement fibre.