Optical fiber with suppressed stimulated Brillouin scattering and method for making such a fiber

A method for making an optical fiber having an increased threshold for the onset of Stimulated Brillouin Scattering (SBS), comprising:

• providing a preform having at least a core part;
• drawing a fiber from the preform, the fiber having a core corresponding to the core part of the preform and a longitudinal axis;
• and
• providing a distribution of propagation velocities in the core for an acoustic wave associated with SBS, said distribution of propagation velocities being at least one of a) azimuthally asymmetric or b) longitudinally asymmetric wherein the core includes a first portion having a propagation velocity that is substantially the same throughout interposed between longitudinally spaced portions each having a propagation velocity different than that of the first portion,
• wherein said distribution of propagation velocities increases the threshold for the onset of SBS of the optical fiber.

A method for making an optical fiber having an increased threshold for the onset of Stimulated Brillouin Scattering (SBS), comprising:

• providing a preform having at least a core part;
• drawing a fiber from the preform, the fiber having a core corresponding to the core part of the preform;
• and
• asymmetrically transferring thermal energy with at least one of the preform or the fiber,
• wherein said asymmetrically transferring thermal energy step increases the threshold for the onset of SBS of the optical fiber.

An optical fiber having an increased threshold for the onset of Stimulated Brillouin Scattering (SBS) and a longitudinal axis, comprising:

• a longitudinally extending core;
• a longitudinally extending cladding disposed about said core;
• two or more longitudinally extending portions, each of said two or more longitudinally extending portions having an outer perimeter and including the area within the outer perimeter of the portion, each of said two or more longitudinally extending portions having throughout a propagation velocity for an acoustic wave that is different than a propagation velocity, for the acoustic wave, of the fiber material contiguous with the portion;
• said two or more longitudinally extending portions having a distance between them that is less than an acoustic phonon damping distance associated with the SBS;
• and
• wherein said two or more longitudinally extending portions increase the threshold for the onset of the SBS of the optical fiber.

An optical fiber having an increased threshold for the onset of Stimulated Brillouin Scattering (SBS) and a longitudinal axis, comprising:

• a longitudinally extending core;
• a longitudinally extending cladding disposed about said core;
• two or more longitudinally extending portions, each of said two or more longitudinally extending portions having an outer perimeter and including the area within the outer perimeter of the portion, each of said two or more longitudinally extending portions having throughout a propagation velocity for an acoustic wave that is different than a propagation velocity, for the acoustic wave, of the fiber material contiguous with the portion;
• said two or more longitudinally extending portions having a distance between them that is less than 500 microns;
• and
• wherein said two or more longitudinally extending portions increase the threshold for the onset of the SBS of the optical fiber.