Light diffusing fibers and methods for making the same

A method for producing a light diffusing optical fiber, the method comprising:

• forming an optical fiber preform comprising a preform core portion having randomly distributed voids;
• drawing the optical fiber preform into an optical fiber such that the randomly distributed voids are drawn into elongated voids that are substantially parallel to a long axis of the optical fiber;
• rotating the optical fiber about the long axis of the optical fiber such that, after rotating, the elongated voids are helical voids wrapped around the long axis of the light diffusing optical fiber such that an angle between the long axis and the helical voids is non-zero.

A light diffusing optical fiber for use in an illumination device, the light diffusing optical fiber comprising:

• a core portion formed from silica-based glass and comprising helical voids randomly distributed in the core portion and wrapped around a long axis of the light diffusing optical fiber such that an angle between the long axis and the helical voids is non-zero, a pitch of the helical voids varying along an axial length of the light diffusing optical fiber;
• and
• a cladding surrounding and in direct contact with the core portion, wherein light guided by the core portion is scattered by the helical voids radially outward and through the cladding such that the light diffusing optical fiber emits light with a predetermined intensity over the axial length of the light diffusing optical fiber, the light diffusing optical fiber having a scattering induced attenuation loss greater than about 0.2 dB/m at a wavelength of 550 nm, wherein the pitch of the helical voids is less than 0.20 m.

A light diffusing optical fiber for use in an illumination device, the light diffusing optical fiber comprising:

• a core portion formed from silica-based glass and comprising helical voids randomly distributed in the core portion and wrapped around a long axis of the light diffusing optical fiber such that an angle between the long axis and the helical voids is non-zero, a pitch of the helical voids varying along an axial length of the light diffusing optical fiber;
• and
• a cladding surrounding and in direct contact with the core portion, wherein light guided by the core portion is scattered by the helical voids radially outward and through the cladding such that the light diffusing optical fiber emits light with a predetermined intensity over the axial length of the light diffusing optical fiber, the light diffusing optical fiber having a scattering induced attenuation loss greater than about 0.2 dB/m at a wavelength of 550 nm, wherein the pitch of the helical voids is less than or equal to 0.20 m and greater than or equal to 0.01 m.

A light diffusing optical fiber for use in an illumination device, the light diffusing optical fiber comprising:

• a core portion formed from silica-based glass and comprising helical voids randomly distributed in the core portion and wrapped around a long axis of the light diffusing optical fiber such that an angle between the long axis and the helical voids is non-zero, a pitch of the helical voids varying along an axial length of the light diffusing optical fiber;
• and
• a cladding surrounding and in direct contact with the core portion, wherein light guided by the core portion is scattered by the helical voids radially outward and through the cladding such that the light diffusing optical fiber emits light with a predetermined intensity over the axial length of the light diffusing optical fiber, the light diffusing optical fiber having a scattering induced attenuation loss greater than about 0.2 dB/m at a wavelength of 550 nm, wherein the pitch of the helical voids increases from an input end of the light diffusing optical fiber to an output end of the light diffusing optical fiber.