A fiber-optic interferometric system comprising: - a light source adapted to emit a source beam at a wavelength λ 0 in vacuum; - a fiber optic coil forming a ring optical path; - a coil splitter adapted to spatially separate the source beam into a first split beam and a second split beam, so that the first split beam and the second split beam travel through the fiber optic coil in opposite directions, the coil splitter being adapted to recombine said first split beam and second split beam after propagation in opposite directions in the fiber optic coil, so as to form an interferometric beam; - a receiver splitter adapted to guide the interferometric beam towards a photodetector; - polarization filtering means comprising: - a first waveguide polarizer, - at least one section of optical waveguide (12, 13, 14), characterized in that the polarization filtering means comprise: - at least one other thin-plate polarizer (52, 53, 54) having a physical thickness e and a refractive index n, and - the first polarizer and the at least one polarizer (52, 53, 54) being juxtaposed in series in the optical path between the receiver splitter and the fiber optic coil, - the at least one other thin-plate polarizer (52, 53, 54) being interposed between, on the one hand, a first waveguide end (21, 31, 41) of the first polarizer and, on the other hand, a second waveguide end (22, 23, 24) of said optical waveguide section 12, 13, 14), the physical distance d between the first waveguide end (21, 31, 41) of the first polarizer and the second waveguide end (22, 23, 24) of said optical waveguide section (12, 13, 14) being lower than or equal to twice the Rayleigh length, i.e.: d ≤ 2 π w 0 2 λ m, where λ m = λ 0 n represents the wavelength of the beam in a medium of index n, w 0 represents the radius of a single-mode beam at 1/e in amplitude in said waveguides of said optical waveguide section (12, 13, 14) and of the first waveguide polarizer, and - the physical thickness e of the at least one other polarizer (52, 53, 54) being lower than or equal to the physical distance d. - a light source adapted to emit a source beam at a wavelength λ 0 in vacuum; - a fiber optic coil forming a ring optical path; - a coil splitter adapted to spatially separate the source beam into a first split beam and a second split beam, so that the first split beam and the second split beam travel through the fiber optic coil in opposite directions, the coil splitter being adapted to recombine said first split beam and second split beam after propagation in opposite directions in the fiber optic coil, so as to form an interferometric beam; - a receiver splitter adapted to guide the interferometric beam towards a photodetector; - polarization filtering means comprising: - a first waveguide polarizer, - at least one section of optical waveguide (12, 13, 14), - a first waveguide polarizer, - at least one section of optical waveguide (12, 13, 14), - at least one other thin-plate polarizer (52, 53, 54) having a physical thickness e and a refractive index n, and - the first polarizer and the at least one polarizer (52, 53, 54) being juxtaposed in series in the optical path between the receiver splitter and the fiber optic coil, - the at least one other thin-plate polarizer (52, 53, 54) being interposed between, on the one hand, a first waveguide end (21, 31, 41) of the first polarizer and, on the other hand, a second waveguide end (22, 23, 24) of said optical waveguide section 12, 13, 14), the physical distance d between the first waveguide end (21, 31, 41) of the first polarizer and the second waveguide end (22, 23, 24) of said optical waveguide section (12, 13, 14) being lower than or equal to twice the Rayleigh length, i.e.: d ≤ 2 π w 0 2 λ m, where λ m = λ 0 n represents the wavelength of the beam in a medium of index n, w 0 represents the radius of a single-mode beam at 1/e in amplitude in said waveguides of said optical waveguide section (12, 13, 14) and of the first waveguide polarizer, and - the physical thickness e of the at least one other polarizer (52, 53, 54) being lower than or equal to the physical distance d.