Patent ID: 8385376

Claim:
An external-cavity laser source generating a useful laser beam (Fu) comprising at least one laser diode LD ( 10 ) mounted in an extended optical cavity ( 30 , 82 ) bounded between two reflecting surfaces ( 92 , 48 ), providing an optical path for a laser beam Fd generated by the laser diode LD, and a mode selection filter ( 44 , 86 ) in the optical path of the cavity in order to select a resonance mode from a number of resonance modes of the laser beam in the cavity, wherein the extended cavity ( 82 ) includes, in its optical path, an optical device ( 94 ) comprising a polarizer ( 100 ) that lets through 100% of a linear polarization of the beam Fd generated by the laser diode, having a reference polarization angle θ 0 of 0°, a polarization rotator ( 102 ) that rotates a polarization of a beam (Fc 1 ) leaving the polarizer through a predetermined rotation angle θ 1 , a polarization splitter ( 104 ) for splitting a beam (Frt) leaving the polarization rotator, the polarization splitter being inclined in the cavity so that its transmission axis (tt′) is oriented at an angle (−θ 1 ) of opposite sign to and of the same value as the polarization angle of the beam (Frt) leaving the rotator ( 102 ), the optical device preventing a reflection beam (Fretum), namely the reflection of the useful beam (Fu), from returning to the laser diode LD.