Patent ID: 6868099

Claim:
A high power diode laser system having narrow spectral width output comprising: (a) a high power diode laser that produces multimode laser light output at power levels of at least one watt and having a relatively broad spectral range; (b) a collimating element positioned to receive the output of the laser diode and provide a collimated output beam; and (c) a diffraction grating mounted to receive the collimated beam from the collimating element on a beam path, the diffraction grating oriented at an angle to the collimated beam such that a portion of the light in the collimated beam incident on the grating is directed back on the beam path to the collimating element and is focussed on the diode laser to provide feedback thereto to narrow the spectral range of the laser light output; and (d) a polarization rotation element in the beam path from the collimating element to the diffraction grating, the polarization rotation element oriented such that the light on the beam path passed therethrough to the diffraction grating is oriented with respect to the diffraction grating to provide a selected efficiency of the diffraction grating and to select the amount of light directed back by the diffraction grating toward the diode laser to provide effective feedback without damaging the diode laser, wherein the polarization rotation element is mounted for rotation to allow rotation of the polarization rotation element to select the amount of feedback to the diode laser.