Patent ID: 9352996
Filing Date: 2016-05-31
CPC Classification: C03B,G02B,H01S

Claim Text:
1. A method for making an optical fiber having a first core and a second core spaced from the first core, the method comprising: (a) providing an optical fiber preform extending in a longitudinal direction, the optical fiber preform comprising: a first core; a second core spaced from the first core; and first and second regions, said first region when viewed in cross section having an outer perimeter having a first substantially straight length and the second region having an outer perimeter having a second substantially straight length facing said first substantially straight length, the first straight length and the second straight length being contiguous and substantially parallel; one of said first and second regions comprising said first core and a cladding disposed about said first core and the other of said first and second regions comprising said second core and a cladding disposed about said second core; said optical fiber preform being constructed and arranged such that the optical fiber preform can be drawn; and (b) drawing the optical fiber from the optical fiber preform while rotating the optical fiber preform about an axis passing through the first core to provide the optical fiber, wherein the optical fiber is configured such that the first core of the optical fiber is multimode at a selected wavelength of operation and the second core of the optical fiber is spaced apart from and winds around the first core of the optical fiber and has a selected longitudinal pitch, wherein at said wavelength of operation the second core of the optical fiber couples to a higher order mode of the first core of the optical fiber and increases the attenuation thereof relative to the fundamental mode of the first core of the optical fiber, and wherein the term “cross section” means cross section taken perpendicular to the longitudinal direction.