Low reflectivity fiber bragg grating with rectangular reflection function
AssigneeCorning Incorporated
InventorsDonald B. Keck, Robert A. Modavis
Life of this patent
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Abstract
Fiber Bragg gratings of low reflectivity are given a squared reflectivity function in the form of a tophat configuration having a flat top and lacking undesirable side lobes. Such a reflectivity function for a fiber Bragg grating is achieved by interfering a diffracted beam with a plane wavefront beam so as to impose a sinc function on the resulting interference pattern that imprints the grating on an optical fiber.
Claims23
A fiber Bragg grating having a core patterned with a varied index of refraction corresponding to varied intensities of an interference pattern of actinic radiation incident on the fiber core from interference of a plane wavefront beam and a diffracted beam.
A method of making a fiber Bragg grating having a core patterned with a varied index of refraction, said method comprising:
- a. providing a fiber having a core that can be patterned by actinic radiation;
- b. arranging angled beams of actinic radiation to form an interference pattern incident on the fiber core;
- c. arranging a first one of the beams to have a plane wavefront;
- and
- d. arranging a second one of the beams to be diffracted.
A fiber Bragg grating having a refractive index distribution, n, expressible as:
- n=n.sub.co +.DELTA.n[1+f(z)cos(Kz)]
- where:
- n.sub.co is a refractive index of a core of the grating,
- .DELTA.n is an induced difference in the refractive index of the core,
- f(z) is an envelope function of the grating, and ##EQU6## is a grating wave vector for a grating period .LAMBDA., the grating comprising:
- the envelope function f(z) being a sinc function, and the sinc function being obtained by interfering a plane wavefront beam with a diffracted beam.
Dependencies are inferred from the claim text.