Michael Alan Feldman

US Patent:

6952507, Oct 4, 2005

Filed:

Nov 12, 2002

Appl. No.:

10/291805

Inventors:

Eric G. Johnson - Oviedo FL, US
Michael R. Feldman - Charlotte NC, US
Thomas J. Suleski - Charlotte NC, US

Assignee:

Digital Optics Corp. - Charlotte NC

International Classification:

G02B006/26

US Classification:

385 31, 385 39, 385 33

Abstract:

An optical coupler reduces differential mode delay in a fiber by reducing an amount of light incident on the fiber in a region in which the refractive index is not well controlled. This region of the fiber is typically in the center of the fiber The optical coupler directs light away from the this region and/or provides a high angle of incidence to any light on this region. A diffuser may be used to reduce sensitivity of the coupler to any fluctutations in the output of the light source. The optical coupler does not need to be offset from the center of the multi-mode coupler. A phase function of an azimuthal mode of the fiber may be imposed on the light beam so that a substantial null on axis is maintained even after propogation of the light beam beyond the depth of focus of the coupler. A diffractive element generating a beam which propogates in a spiral fashion along an axis allows the shape of the beam to be maintained for longer than a depth of focus of the diffractive element.