Abstract:
An optical communications system, comprising a first node, first dispersion compensation fiber located in the first node, wherein the first dispersion compensation fiber induces dispersion onto optical signals passing through the first dispersion compensation fiber, a second node, a plurality of spans between the first and second nodes, and second dispersion compensation fiber located in at least one of the spans, wherein the second dispersion compensation fiber induces dispersion onto optical signals passing through the second dispersion compensation fiber, and wherein the dispersion induced by the second dispersion compensation fiber is opposite in sign to that induced by the first dispersion compensation fiber.
Abstract:
An optical fiber is tapered, for example, by heating it with a CO2 laser. The tapering process is controlled such that the taper transition regions have taper angles selected to minimize loss. The taper waist has a diameter selected to introduce desired dispersion properties and desired nonlinearity. The optical fiber can be used as a dispersion compensator in a fiber laser or other fiber optic system. The nonlinearity in the tapered optical fiber allows the generation of ultrashort light pulses.
Abstract:
An improved telecommunications link is provided which includes a dispersion managed fiber with smoothly varying dispersion. The dispersion map may vary sinusoidally or as a sawtooth, for example. The smoothly varying dispersion works well for high data rate transmissions in a return to zero signal format. The dispersion managed fiber with smoothly varying dispersion may be formed by a wide variety of techniques. A method of forming dispersion managed fiber by localized heating or cooling is also provided.
Abstract:
Different pieces of glass (81, 82) are fused together to create a preform (94) from which a glass fiber with axially varying properties is drawn.
Abstract:
An optical fiber and method of making, wherein the optical fiber alternates between regions having different diameters along its length, wherein the refractive index of said blank and the diameters of said fiber are chosen to result in a fiber having alternating regions of positive and negative dispersion at a wavelength which is greater than 1480 nm, yet preferably has a low net dispersion and dispersion slope. A preferred such profile consists of a core region surrounded by a cladding region, said core region comprised of a central core region which is updoped with respect to said cladding region, said central core region surrounded by a moat region which is downdoped with respect to said cladding region, and said moat region is surrounded by an annular ring region which is updoped with respect to said cladding region.
Abstract:
A waveguide, such as a holey fiber or other optical fiber, is tapered to control the dispersion in a manner which varies along the length of the tapered portion of the fiber, thus providing the desired characteristics of the fiber. The longitudinal variation of the phase-matching conditions for Cherenkov radiation (CR) and four-wave mixing (FWM) introduced by DMM allow the generation of low-noise supercontinuum. The flexibility of the design permits the designer to control the tapering to select the bandwidth, the center frequency, or both. The holey fiber can be a polarization-maintaining fiber.
Abstract:
An optical fiber (10) having section (A) of first kind where the chromatic dispersion in a predetermined wavelength band is greater than a predetermined positive value x and the chromatic dispersion slope is negative and section (B) of second kind where the chromatic dispersion in the same wavelength band is smaller than -x and the chromatic dispersion slope is positive, or an optical fiber where the chromatic dispersion in a predetermined wavelength band is greater than the predetermined positive value x and the chromatic dispersion slope is negative.
Abstract:
Disclosed is a single mode optical waveguide fiber having alternating segments of positive and negative dispersion and dispersion slope. The relative indexes, the refractive index profiles and the radii of the segments are chosen to provide low total dispersion and dispersion slope. One embodiment consists of a first central major index profile (10) of outer radius r1, surrounded by a first annular segment (12) of outer radius r2, surrounded by second annular segment (14) of outer radius r3. Preferred waveguides in accordance with the invention exhibit a dispersion over the range of 1520 to 1625 nm which at all times have a magnitude which is less than 2, and more preferably less than 1 ps/nm -km. The total dispersion of the waveguide fiber is in the range of about -2.0 to +2.0 ps/nm-km at 1550 nm. The waveguide also features a low polarization mode dispersion.