Optical fibre sensor

A fiber optic sensor for detecting an excitation in proximity to a fiber optic assembly, said excitation inducing a modulation of the phase of an optical signal propagating in said fiber optic assembly, said sensor comprising:

• a laser assembly of at least one laser, said laser assembly being configured to emit at least one laser beam;
• a fiber optic assembly having a first end and a second end;
• an optical system configured to:
• inject via said first or said second end, at least one portion of said laser beam;
• receive via said first end, at least one signal beam issued from the portion of the laser beam injected into and propagated in said fiber assembly;
• generate at least one reference beam from said laser beam or said signal beam;
• produce at least one interference zone corresponding to the interference between a portion of the reference beam and a portion of the signal beam;
• a digital holography assembly comprising:
• a liquid-crystal spatial light modulator configured to receive a portion of the signal beam and a portion of the reference beam;
• a video camera configured to receive said interference zone generating an interference pattern, said interference pattern being addressed electrically to said liquid-crystal spatial light modulator in order to create thereon a phase hologram corresponding thereto;
• at least one optical detector configured to detect an output optical signal beam resulting from:
• the diffraction of said portion of the signal beam and/or said portion of the reference beam received by the hologram inscribed in said liquid-crystal spatial light modulator and
• the transmission of said portion of the reference beam and/or said portion of the signal beam transmitted by said liquid-crystal spatial light modulator;
• a processing unit, connected to the output of said optical detector, for processing said output optical signal beam, allowing information relative to said excitation to be extracted.