Office National D'etudes Et De Recherches Aerospatiales (onera)

Office National D'etudes Et De Recherches Aerospatiales

Onera (office National D'etudes Et De Recherches Aerospatiales)

Onera

Laurent Lombard

Jerome Primot

Jérôme Primot

Guillaume Canat

Didier Fleury

Cindy Bellanger

Maxime Deprez

William Renard

Julien Le Gouët

Anne Durecu

Nicolas Cezard

François Gustave

Agnès Dolfi-bouteyre

Julien Le GOUËT

A LIDAR system is adapted for performing differential absorption measurements of a chemical compound between two distinct optical frequencies (ν1, ν2), and for measuring a separation distance from an obstacle which is present in a background of a measurement zone where the absorption occurs. An emission optical power value is varied between different time intervals during a radiation emission sequence, in order to allow that the LIDAR system implements an optical fiber technology while having sufficient emission power. The LIDAR system makes it possible to evaluate an amount of the chemical compound which is contained in the measurement zone, as well as a separation distance from an obstacle which is located in the background of the measurement zone.

LIDAR system for differential absorption and background distance measurements

A wavefront analyzer is modified to simply determine the differences in amplitude and tilt which can exist between the different regions of an initial wavefront (S). To achieve this, interference between two waves only is produced from beams (F, F) which come from neighboring regions on the initial wavefront. Such an analyzer can be used to coherently combine laser radiation produced by different sources arranged in parallel. Another use is for the determination of the differences in height and inclination which exist between the neighboring mirror segments of a Keck telescope.

Wavefront sensor and method for determining differences in piston and tilt existing between several light beams

According to one aspect, the invention relates to a device comprising an optical fiber having a high Brillouin threshold, said device including an optical fiber () suitable for propagating a high-power optical signal beam, means () for coupling a signal beam to an entrance end of the optical fiber () and a tubular structure () comprising at least one first tube () and at least one first adhesive material (). According to the present description, at least one portion of the optical fiber is immobilized in the tubular structure () by means of the first adhesive material (), which adheres both to the internal surface of the first tube () and to the external surface of the optical fiber (). Furthermore, at room temperature and with no other external stresses on the device, the immobilized portion of the optical fiber () is maintained in a compressive state by the tubular structure, the compressive state being such that the relative deformation of the optical fiber is negative or zero in its portion immobilized in the tubular structure, the maximum value of the relative deformation of the immobilized portion of the optical fiber being higher in absolute value than 0.3%.

Device comprising an optical fiber having a high brillouin threshold and method for manufacturing such a device

According to one aspect, the invention relates to an optic fiber amplifier having a high Brillouin threshold, and including: an amplification optic fiber () comprising a core and a sheath and suitable for amplifying a signal beam travelling in said core; means for coupling the signal beam in an input end of said amplification optic fiber; means for coupling a pump laser beam for pumping said amplification optic fiber; a structure () including a deformable portion around which at least one portion of said amplification optic fiber is wound in the shape of turns, said turns being in contact with a surface of said deformable portion, wherein the friction of said optic fiber on said surface resulting, during the deformation of said deformable portion, in an elongation of said amplification optic fiber according to an elongation profile that varies from one turn to the other.

Optic fiber amplifier having a high Brillouin threshold and method for making such an amplifier

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Paris, France

Laurent Lombard