France Telecom

Auckland Uniservices Limited

Sa Highwave Optical Technologies

David Mechin

Philippe Grosso

John Harvey

Claude Aguergaray

Vladimir Kruglov

Neil Broderick

Michel Nolf

A laser apparatus for producing mode locked pulses includes a closed optical system adapted to connect to a fiber grain medium to form a laser cavity. The fiber gain medium is adapted to receive pulses characterized by a first state and to output pulses characterized by a second state. The closed optical system is adapted to receive the pulses in the second state and output pulses in a state similar to the first state.

Laser device

The invention provides a method of photoinducing a Bragg grating in an optical fiber () or a waveguide, in which a selected zone of the fiber () or waveguide is subjected to a step of being exposed with a source beam () using a mirror () in such a manner as to fold a portion () of the source beam () as reflected by the mirror () onto a portion () of the source beam that is not reflected by the mirror, thereby obtaining a diffraction grating in the fiber () or waveguide, the method being characterized in that an additional exposure step is performed on said portion of the fiber () or waveguide, and in that relative displacement is imparted between the two exposure steps to elements selected from the beam (), the fiber () or waveguide, and the mirror () in such a manner as to cause a same portion of the beam () used for photoinduction in both exposure steps to be reflected by the mirror () in one of the steps and not reflected by the mirror () in the other step.

Apodization method for a bragg grating

The invention relates to an exposure method for producing a Bragg grating on a photosensitive guide ( ) or optical fiber ( ), in which method the guide (the fiber) ( ) is scanned by a light beam ( ) and means ( ) are provided for modulating the exposure time along the guide (the fiber) by varying the speed at which the beam ( ) moves along the guide (the fiber) ( ) so that it is located opposite each location of the guide (the fiber) ( ) for a time period that varies with the location, the method including the step of disposing in front of the guide (the fiber) ( ) a system ( ) adapted to create interference fringes on the guide (the fiber) ( ) and to scan the beam ( ) over the interference system ( ) at a speed that is modulated along the system ( ), and furthermore the step of having the beam scan the guide (the fiber) ( ) at a modulated speed without the interference system ( ) on the path of the beam ( ), the scanning with the interference system ( ) being effected with modulation of the exposure time increasing the exposure time in the central part of the guide (the fiber) ( ) and the scanning without the interference system being effected with modulation of the exposure time reducing the exposure time in the central part of the guide (the fiber) ( ).

Photowritten Bragg grating apodization method

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Lannion, France

David Mechin