Interferometric measurement system with optical fibre and inertial guidance or navigation system including such an interferometric measurement system

A fiber-optic interferometric measurement system including:

• a broad-spectrum light source adapted to emit a source light beam;
• a beam splitter adapted to receive the source light beam and to form a first split source beam and a second split source beam;
• first optical transmission means of optical length l1 adapted to transmit the first split source beam and second optical transmission means of optical length l2 adapted to transmit the second split source beam;
• a first Sagnac ring interferometer including a first fiber-optic coil and a first individual integrated optical circuit connected on the one hand to the first optical transmission means and on the other hand to the two ends of the first fiber-optic coil, the first fiber-optic coil having a length L1 and a group birefringence index difference ΔNb1;
• a first detector adapted to detect a first interferometric signal formed by the propagation of the first split source beam in the first Sagnac ring interferometer;
• a second Sagnac ring interferometer comprising a second fiber-optic coil and a second individual integrated optical circuit connected to the second optical transmission means and to the two ends of the second fiber-optic coil, the second fiber-optic coil having a length L2 and a group birefringence index difference ΔNb2;
• a second detector adapted to detect a second interferometric signal formed by the propagation of the second split source beam in the second Sagnac ring interferometer;
• and a multiple integrated optical circuit integrating on a same substrate the first individual integrated optical circuit and the second individual integrated optical circuit, wherein
• the difference Δl between the optical length l1 of the first optical transmission means and the optical length l2 of the second optical transmission means is higher than the maximum of ΔNb1×L1 and ΔNb2×L2.