Patent ID: 7907656

Claim:
An optical harmonic frequency conversion module comprising: a semiconductor fiber coupled laser generating a substantially linearly polarized light output of a first linear polarization mode; a non-linear crystal device for converting the light output from the fiber laser having a first frequency at the first linear polarization mode into an output light having a second frequency; and a polarization maintaining optical fiber link for coupling the substantially linearly polarized light output of the first linear polarization from the fiber laser into the non-linear crystal device, the PM optical fiber link including a plurality of polarization distortion points introducing a second parasitic linear polarization mode; and at least one polarizer disposed in the polarization maintaining optical fiber link following at least one polarization distortion point in the direction of optical transmission from the fiber laser, wherein one at least one polarizer is disposed in the polarization maintaining optical fiber link immediately prior to coupling into the non-linear crystal device.