Compact laser source with reduced spectral width
First Claim
1. 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 (Fc1) 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.
1 Assignment
0 Petitions
Accused Products
Abstract
The invention relates to a laser source with an external cavity generating a useful laser beam (Fu), that comprises at least one laser diode DL (10) mounted in an extended optical cavity (30, 82) defined between two reflecting surfaces (92, 48) forming an optical path for a laser beam Fd generated by the laser diode DL, a mode selection filter (44, 86) in the optical path of the cavity for selecting a resonance mode from a range of resonance modes of the laser beam in the cavity. The extended cavity (2) includes in the optical path thereof an optical device (94) including a polariser (100) that is 100% permissive to a rectilinear polarisation of the beam Fd generated by the laser diode, the reference polarisation angle θ0being of 0 degrees, a polarisation rotator (102) of the beam at the output of the polariser (Fc1) by a predetermined rotation angle θ−1, a polarisation separator (04) of the beam (Frt) at the output of the polarisation rotator, the polarisation separator being inclined in the cavity so that its transmission axis (tt′) is oriented at an angle (−θ−1) having an opposite sign to and the same value as the polarisation angle of the beam (Frt) at the output of the rotator (102), wherein the optical device prevents any feedback of a reflection beam (Fretum) of the useful beam (Fu) towards said laser diode DL. The invention can be used in a laser for cooling atoms, in interferometry experiments, inertial sensors and atomic clocks.
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Citations
12 Claims
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1. 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 (Fc1) 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. - View Dependent Claims (2, 3, 4, 5, 9, 10, 11, 12)
-
0 of 0°
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6. The external-cavity laser source as claimed in claim, wherein the polarization rotation angle (θ
-
1) of the beam (Frt) leaving the polarization rotator (102) is chosen to be +28°
, the transmission axis (tt′
) of the polarization splitter (104) being in this case oriented at −
28° and
the reflection axis (rr′
) oriented at 90−
θ
1, i.e. +62°
.
-
1) of the beam (Frt) leaving the polarization rotator (102) is chosen to be +28°
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7. The external-cavity laser source as claimed in claim, wherein the rotator (102) is a Faraday rotator.
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8. The external-cavity laser source as claimed in claim, wherein the mode selection filter (86) is an interference filter.
Specification