Abstract: The invention relates to a broadband light source including an amplifying guide structure (1). The light source includes a device (45) of exciting the guide structure (1). The stimulated guide structure (1) emits light (7, 8) that accepts strong spatial coherence and weak time coherence. The light (7) is transmitted forwards (2) having a spontaneous emission spectrum. The light source also includes a rear mirror (5), reflecting only for a narrower range of wavelengths than the spontaneous emission spectrum and produces emission (E) forwards (2) with an emission spectrum controlled around an average wavelength. The rear mirror is inserted between the excitation means and the guide structure.

Abstract: This invention relates to a singlemode laser source tunable in wavelength with a self-aligned external cavity, comprising: a resonant cavity having an output face that is partially reflecting (331) and a retroreflecting dispersive device (31, 39), defining a main collimating axis (351) and a secondary collimating axis (381), an amplifier wave guide (33) placed in position inside the resonant cavity. The retroreflecting dispersive device comprises a plane diffraction grating (31) having dispersion planes and an orthogonal reflecting dihedral (39) whose line of intersection (391) is parallel to the dispersion plane of the diffraction grating containing the collimating axes (351, 352).

Abstract: This invention relates to a singlemode laser source tunable in wavelength with a self-aligned external cavity, comprising: a resonant cavity having an output face that is partially reflecting (331) and a retroreflecting dispersive device (31, 39), defining a main collimating axis (351) and a secondary collimating axis (381), an amplifier wave guide (33) placed in position inside the resonant cavity. The retroreflecting dispersive device comprises a plane diffraction grating (31) having dispersion planes and an orthogonal reflecting dihedral (39) whose line of intersection (391)is parallel to the dispersion plane of the diffraction grating containing the collimating axes (351, 352).

Abstract: The invention relates to a fiber optic measuring device in which the variation in a measured parameter engenders a phase difference between two waves. It comprises a SAGNAC ring interferometer (2) in which two counter-propagating waves propagate; a polarization splitter (6) spatially splits the two polarizations which will propagate in the interferometer (2), interferometer (2) comprises a polarization conserving birefringent fiber (7) having two ends having neutral birefringence axes, each of the ends of the polarization conserving fiber (7) being connected to one of the gates (6b) and (6c) of the polarization splitter (6). It comprises a birefringent component, placed ahead of the polarization splitter (6) and introducing a path difference greater than the coherence length of the source (1) between the two polarized waves.

Abstract: A fiber optic measuring device can be used, for example, as a rate gyro. Variation in a measured parameters engenders a phase difference between two waves. The measuring device includes a light source 1, a SAGNAC ring interferometer 2, a detector 3, a phase modulator 4, and a electronic unit 7. The electronic unit 7 includes a processing system 9 which furnishes a signal that is a function of the measured parameter and an electronic sub-unit 12 for controlling the phase modulator 4. The control signal for the modulator is a superposition of a first, periodic gating, bias signal .PHI..sub.b (t) with period 2.tau. and amplitude .PHI..sub.bm, and of a second, staircase, negative-feedback signal .PHI..sub.m (t) synchronized with .PHI..sub.b (t), each step of which has a duration equal to .tau. or to one of its sub-multiples, and an amplitude .PHI..sub.s, which is a function of the value of the measured parameter and which falls back to zero when its amplitude exceeds a predetermined value .PHI..sub.mm . .PHI..

Abstract: The invention relates to a fibre optic measuring device of the type in which the change in a measured parameter generates a phase difference between two waves in a SAGNAC ring interferometer (2). Electronic means (7) comprise a processing system (9) delivering a signal depending on the measured parameter and electronic means (12) controlling the phase modulator (4). The electronic means (12) produce a control signal for the modulator determined in such a way that the phase difference .delta..PHI..sub.m which it produces between the counter-propagating waves periodically takes the following four successive values: ##EQU1## where .PHI..sub.o is a constant phase shift and it depends on a, and a is a positive constant satisfying the condition: cos .PHI..sub.o =cos a.PHI..sub.o.

Abstract: A method of positioning an object relative to a plane, and apparatus therefor. According to the method, the plane is swept by the axis of a light-beam between a source assembly and a detection assembly, and the object is translated approximately perpendicularly to the plane, the detection assembly emitting a signal representative of the light received and therefore, the position of the object relative to the plane. The signal emitted by the detection assembly is measured as a function of time, the translation of the object being halted when the signal has a particular form. The particular form of the signal corresponds to the position of the object in which the shoulder masks a predetermined fixed part of the light-beam during part of its sweep.

Abstract: A measuring method and device are provided based on the analysis of a channelled light spectrum, particularly for measuring a low amplitude movement of a mobile surface, possibly representative of the variation of a physical magnitude convertible into such a movement.

Abstract: A vibration detection device is provided having multimode optical fiber as sensitive element; a coherent light source; photodetecting means; means for analyzing the output of the photodetector means; a monomode optical fiber disposed between the coherent light source and the first end of the multimode optical fiber forming the input face thereof; and at least one optical fiber, whose core diameter is smaller than that of the multimode optical fiber, disposed between the other end of the multimode optical fiber, forming the output face thereof and on which a speckle appears, and the photodetector means.