Patents Assigned to DFS Fitel LLC
  • Patent number: 8036503
    Abstract: An optical delay line is formed from a coil of optical fiber (in many cases microfiber), where the radius of the optical fiber is greater than the wavelength ? of the propagating signal and the radius R of the coil is selected, in consideration with the optical fiber radius, to limit propagation loss by minimizing coupling between adjacent turns of the coil. The difference in dimension between the fiber diameter and wavelength prevents the mode propagating along one turn from coupling into an adjacent turn. It has been discovered that the modal intensity at the interface between the central rod and the coil will be minimized when the radius of the fiber satisfies the following condition: r >> ( R ? 2 ) 1 / 3 , where ?=(2?n)/?, and n is the refractive index of the fiber.
    Type: Grant
    Filed: October 13, 2009
    Date of Patent: October 11, 2011
    Assignee: DFS Fitel LLC
    Inventor: Mikhail Sumetsky
  • Patent number: 7760978
    Abstract: An optical transmission fiber is formed to include a relatively low-index, relatively thin outer cladding layer disposed underneath the protective polymer outer coating. Stray light propagating along an inner cladding layer(s) within the fiber will be refracted into the thin outer cladding (by proper selection of refractive index values). The thin dimension of the outer cladding layer allows for the stray light to “leak” into the outer coating in a controlled, gradual manner so as to minimize heating of the coating associated with the presence of stray light. The inventive fiber may also be bent to assist in the movement of stray light into the coating.
    Type: Grant
    Filed: September 8, 2008
    Date of Patent: July 20, 2010
    Assignee: DFS Fitel LLC
    Inventors: David John DiGiovanni, Yoshihiro Emori, Michael Fishteyn, Clifford Headley