Patent ID: 6542689
Filing Date: 2003-04-01
Classification: G02B

Abstract:
A method of attenuating light signals propagating in an optical fiber by a desired value, the fiber having a defined core radius (a) and core/cladding index difference ratio (&Dgr;), wherein a coating surrounds the cladding of the fiber for protecting the cladding from scratching, a buffer material surrounds the coating to protect the fiber further from mechanical damage, and an insulating cable jacket provides an outer covering for a cable in which the coated fiber and the buffer material are contained, the method comprising:removing a determined axial length of the cable jacket from the cable at a given location where attenuation is desired to be introduced in the optical fiber contained in the cable, thus exposing an outer surface of the buffer material; determining a fundamental resonant coupling period (&Lgr;) for light signals propagating in the optical fiber in the absence of said buffer material, wherein &Lgr;=2&pgr;a/(2&Dgr;)Â½, where a is the core radius of the fiber, and &Dgr; is the core/cladding index difference ratio for the fiber;clamping a grating on the exposed outer surface of the buffer material with a certain clamping force, wherein said grating has a period that is N times said fundamental grating period, and N is a positive integer equal to or greater than two; and adjusting the clamping force until the desired value of attenuation is obtained at the given location in the optical fiber contained in the cable.