Patent ID: 9014522
Filing Date: 2015-04-21
Classification: B29D,G02B,H01S

Abstract:
1. An optical coupler for use with a polarization-maintaining input optical fiber and polarization-maintaining output optical fiber, the optical coupler comprising: a tube having a wide end, a narrow end having an end face, and a taper therebetween; a polarization-maintaining feed-through optical fiber having a first end having an end face and a second end, the polarization-maintaining feed-through optical fiber being disposed within the tube from the wide end to the narrow end, at least the narrow end of the tube being fused around a first length of the polarization-maintaining feed-through optical fiber including the first end of the polarization-maintaining feed-through optical fiber to form a coupler end face comprising the end face of the tube and the end face of the first end of the polarization-maintaining feed-through optical fiber, wherein the polarization-maintaining feed-through optical fiber has an outer diameter no greater than about 200 μm at the coupler end face and throughout the region in which the tube is fused around it, wherein the diameter of the core of the polarization-maintaining feed-through optical fiber is not substantially tapered as it traverses the tube from the wide end of the tube to the end face of the optical coupler; wherein the polarization-maintaining feed-through optical fiber comprises a core, a cladding surrounding the core and forming the outer surface of the polarization-maintaining feed-through optical fiber, and one or more birefringence-inducing elements disposed in the cladding, wherein the one or more birefringence-inducing elements do not extend beyond a diameter of 150 μm, and do not extend to the outer surface of the cladding of the polarization-maintaining feed-through optical fiber in the region in which the tube is fused around it.