Patent ID: 7826132

Claim:
An optical harmonic frequency conversion module comprising: a semiconductor fiber laser generating a substantially linearly polarized light output; a non-linear crystal waveguide device for converting the light output from the semiconductor fiber laser having a first frequency into an output light having a second frequency; and an optical fiber link for coupling the substantially linearly polarized light output from the semiconductor fiber laser into the non-linear crystal waveguide device, the optical fiber link comprising birefringent optical fiber having a fast axis, and a slow axis orthogonal thereto, wherein the optical fiber link includes at least one 90 degree splice fusing a fast axis of a first segment of birefringent optical fiber to a slow axis of a second segment of birefringent optical fiber, wherein the optical fiber link includes two major PER (polarization extinction ratio) degradation points and the at least one 90 degree splice is disposed such that light launched into a fast axis of the optical fiber link has a substantially equal optical path length as light launched into a slow axis of the optical fiber link between the two major PER degradation points.