Abstract: The invention relates to a monomodal optical fibre hydrophone operating by elastooptical effect, which has an interferometer structure comprising a measuring arm, in which is arranged a very long monomodal optical fibre immersed in the interaction medium in which propagates the soundwave. A phase displacement is induced by an elastooptical effect on the soundwave propagating in the fibre, by a soundwave producing an acoustic pressure field in said medium. A reference arm establishes a reference optical path and the phase displacement, linked with the sound wave, is detected by interferometry between the two optical waves coming from these two arms. This two-armed interferometer is terminated by a photorefractive medium used as an interactive reflector in accordance with the four-wave interferometry principle.

Abstract: The invention relates to a process making it possible to produce a drawn object having a chiralic structure. This production process consists of subjecting the object to torsion during its drawing and simultaneously to hardening making it possible to fix part of the thus obtained torsional stresses in the structure.

Abstract: An interferometer having a tunable optical resonator using a monomode optical fiber as the light propagation medium. According to a preferred embodiment the fiber (1) is wound around a cylindrical mandrel (7) made from a piezoelectric ceramic material. Multiple reflections are ensured by reflecting deposits at the fiber ends. Rapid scanning of several orders of interference can be obtained by applying an alternating voltage V to the ceramic material.

Abstract: The invention relates to ring interferometers. It aims at making strictly reciprocal a ring interferometer of any known structure, by means of a mode filter which allow a particular mode to be selected among all the modes likely to be propagated in the loop and to arrive at the detection device; this filtering is carried out by a mode filter comprising for example a screen pierced with a hole or an integrated wave-guide or optical fiber portion which are advantageously monomode.

Abstract: An integrated optical structure creating directional coupling between two waveguides in which an index disturbance accompanying the guided photons is caused to act on two closely-spaced waveguides, this disturbance being produced by a progressive elastic wave with sloping wavefronts emitted by an electromechanical transducer.

Abstract: The current-measuring device in accordance with the invention comprises an optical fiber wound around the conductor in which flows the current to be measured, a laser source, means for separating the radiation emitted by the source towards the two ends of the wound fiber, and for recombining the radiation emerging from these two ends, a conductor circuit through which flows an adjustable reference current, a detection device supplying a signal characteristic of the interferences between the two waves emerging from the fiber, the reference current being adjusted so that the phase shift between the two contra-rotating waves in the fiber is zero, this current being then proportional to the current to be measured flowing in the principal conductor.

Abstract: A directional coupling device for single multi-mode optical fibers which are disposed coaxially in a transparent body of the coupling device, a suitable space filled with an immersion medium being formed between the end faces of the two fibers; means for introducing light rays and photo-sensitive means for picking up the dispersion flux are respectively arranged on at least one of the ends of the body of the coupling device.