Abstract: A network element comprises a power interface to receive power from a power communication medium; a service interface to provide a telecommunication service over a service communication medium; management interface to receive management data over one of the service communication medium and the power communication medium via at least one primitive; and a control module to monitor the at least one primitive and to control operation of the network element based on the at least one monitored primitive.

Abstract: Endohedral metallofullerene compounds, which in water has a relaxivity of about 30 mM?1 S?1 to about 300 mM?1 S?1 and forms a dispersion in water with entities having an average hydrodynamic radius of less than about 20 nm.

Abstract: A system for managing power from a power source for at least one line powered network element in an access network is provided. The system includes a power manager that establishes at least one power criterion for the at least one network element. Further, the system includes a power controller that is responsive to the power manager. The power controller and the power manager communicate to manage operation of the at least one network element based on the at least one power criterion.

Abstract: Described herein are synthetically modified fullerene molecules, wherein the fullerene is preferably ellipsoid in shape with an equatorial band and two opposing poles, comprising an adduct at one or both poles, at least one adduct being a hydrophobic chemical moiety capable of anchoring the fullerene on or in a lipid membrane.

Abstract: A system for managing power from a power source for at least one line powered network element in an access network is provided. The system includes a power manager that establishes at least one power criterion for the at least one network element. Further, the system includes a power controller that is responsive to the power manager. The power controller and the power manager communicate to manage operation of the at least one network element based on the at least one power criterion.

Abstract: A low noise optical fiber Raman amplifier with integral Raman laser (FRA) is disclosed. The FRA typically comprises a fiber ring with at least two amplifier stages, with strictly counter-propagating pump radiation. Relatively short wavelength (e.g., 1060 nm) pump power is provided to the Raman laser portion of the fiber ring. Appropriately selected and placed Bragg gratings provide one or more optical cavities in the fiber ring, such that the input pump radiation is converted to the desired amplifier pump radiation (e.g., 1240 nm, suitable for amplification of 1310 nm signal radiation). The FRA can, for instance, advantageously serve as power amplifier in digital or analog fiber communication systems, or it can serve as pre-amplifier or in-line amplifier.

Abstract: We have discovered that hydrogen-related loss in silica-based single mode transmission optical fiber can be reduced or eliminated by use of a substrate tube that contains hydrogen getter sites. Exemplarily, substrate tubes according to the invention are doped with Ge or P.

Abstract: A passive optical attenuating device comprises an optical waveguide adapted to receive optical radiation and absorb, along its length, at least 0.2 dB/m of the optical radiation. The waveguide section may be coupled to a low-loss optical fiber so as to receive an optical signal to be attenuated therefrom. In accordance with one aspect of the invention, at least one region of the waveguide is doped with a transition metal to achieve a pre-selected absorptivity per unit length so that a controlled degree of attenuation can be achieved.

Abstract: In accordance with the invention, an optical filter comprises a plurality of optical fibers having a coupling region where the axially extending cores are closely spaced within a common cladding. The coupling region includes a long period grating for selectively shifting light of selected wavelengths from guided modes into non-guided modes. These non-guided modes are picked up by an adjacent core and light of the selected wavelengths is thus shifted from one core to another. The result is an optical filter particularly useful as a demultiplexer or a tapping device. In one embodiment the grating is formed in one of the cores. In an alternative embodiment, it is formed in the common cladding.

Abstract: In accordance with the invention, an optical four-wave mixer for producing a phase-conjugated signal comprises a source of optical input signals, a fiber laser for receiving the signals, and a detector for selectively detecting the frequency-shifted signals produced by four-wave mixing. The laser can be a rare-earth doped fiber laser with a fiber cavity phase matched to the input signals. The frequency-shifted output signals have an inverted spectral waveform as compared with the input signals. The mixer can be made in compact form with a cavity length as small as 100 m and can provide inverted signals at the same intensity as the input signals, making the mixer particularly useful for providing spectral inversion in an optical communications system.

Abstract: A gain control arrangement for an optical amplifier for equalizing its amplification versus wavelength response at specific frequencies. A high loss attenuating fiber with reflective gratings to segregate undesired signals from wanted signals. Using either an optical circulator or a fused fiber splitter the gain control arrangement is coupled to the wide band output of an optical amplifier.

Abstract: In accordance with the invention, the index of refraction of a glassy material is increased by treating the material with hydrogen and applying heat. Specifically, the glass is exposed to hydrogen or deuterium at pressure in the range 14-11,000 p.s.i. and a temperature in the range 21.degree.-150.degree. C. for a time sufficient for the hydrogen to diffuse into the glass. The glass is then subjected to heat in excess of about 500.degree. C., as by application of a flame or infrared radiation. The duration of heating can be less than a second. The result is a substantial and long-lived increase in the normalized refractive index. For example, flame heating of H.sub.2 loaded commercial GeO.sub.2 doped optical fibers (AT&T Accutether single mode fiber) has produced normalized index changes .increment.n/n of 4.times.10.sup.-3. This process can be used to make and adjust a variety of optical waveguide devices.

Abstract: In accordance with the invention, an optical fiber phase shifter comprises a length of asymmetrical optical fiber disposed perpendicular to a magnetic field for providing a non-reciprocal phase shift. Preferably the fiber is wound in a circular coil and exposed to an axial field as from a pancake magnet. In an isolator, the fiber length and magnet strength are chosen to provide non-reciprocal phase shifts of .+-.45.degree. or .+-.90.degree.. The isolator including the phase shifter can be any of several configurations.

Abstract: A 980 nm pump, for use with an erbium-doped fiber amplifier, provides redundancy together with simultaneous pumping, both co-propagating and counter-propagating, relative to 1550 nm signal, without need for an isolator.

Abstract: Disclosed is optical fiber that can advantageously be used to compensate chromatic dispersion in an optical fiber communication system, typically a system that is upgraded from 1.3 .mu.m to 1.55 .mu.m operating wavelength (.lambda..sub.op). The fiber typically has a power law core refractive index profile, a refractive index "trench" surrounding the core, and a refractive index "ridge" surrounding the trench. The refractive index profile of the fiber preferably is designed such that the fiber supports the fundamental mode (LP.sub.01), does not support the LP.sub.11 mode but does support the LP.sub.02 mode, all at .lambda..sub.op. At .lambda..sub.op, LP.sub.01 has dispersion more negative than -150 ps/nm.multidot.km and, in a preferred embodiment, LP.sub.01 also has negative dispersion slope at .lambda..sub.op. In a further embodiment of the invention the refractive index profile is designed such that the cut-off wavelength of the LP.sub.11 mode is less than that of the higher order mode, typically LP.sub.

Abstract: The presence of (typically unintended) birefringence in single mode optical fiber can severely limit the usefulness of the fiber for, e.g., high bit rate or analog optical fiber communication systems, due to the resulting polarization mode dispersion (PMD). It has now been discovered that PMD can be substantially reduced if, during drawing of the fiber, a torque is applied to the fiber such that a "spin" is impressed on the fiber. Desirably the torque is applied such that the spin impressed on the fiber does not have constant spatial frequency, e.g., has alternately clockwise and counterclockwise helicity. At least a portion of optical fiber according to the invention has spin alternately clockwise and counterclockwise.

Abstract: Optical fiber including a core and a clad suitable for use in wavelength division multiplex systems. The fiber can have an attenuation at 1550 nm less than 0.25 dB/km, a cut off wavelength of less than 1.40 .mu.m, and a dispersion slope less than 0.15 ps/(nm.sup.2 -km).

Abstract: The presence of (typically unintended) birefringence in single mode optical fiber can severely limit the usefulness of the fiber for, e.g., high bit rate or analog optical fiber communication systems, due to the resulting polarization mode dispersion (PMD). It has now been discovered that PMD can be substantially reduced if, during drawing of the fiber, a torque is applied to the fiber such that a "spin" is impressed on the fiber. Desirably the torque is applied such that the spin impressed on the fiber does not have constant spatial frequency, e.g., has alternately clockwise and counterclockwise helicity. At least a portion of optical fiber according to the invention has a spin whose spatial frequency exceeds 4 spins/meter.

Abstract: Unexpectedly large normalized refractive index changes (.DELTA.>10.sup.-5, but possibly even larger than 10.sup.-3) can be obtained in oxide glass, e.g., high-silica glass, by a treatment that comprises exposing at least a portion of the glass at a temperature of at most 250.degree. C. to H.sub.2 or D.sub.2 (partial H.sub.2 or D.sub.2 pressure greater than 1 atmosphere), and irradiating at least a part of the exposed portion with actinic (typically UV) radiation. The method can be used to make optical components that comprise a region (or regions) of raised refractive index, e.g., an in-line refractive index grating in an optical waveguide, a planar optical waveguide, or a phase grating.

Abstract: We have discovered that silica-based optical fibers that are doped with Ge, Al and a rare earth (e.g., Er) can be very susceptible to hydrogen-induced attenuation change. For instance, such fiber can exhibit loss increase rates that are, at 20.degree. C., 10.sup.6 times larger than those of a standard single mode fiber. We also believe that transition metal-doped silica-based fibers can exhibit large hydrogen-induced attenuation change. In many circumstances (e.g., amplifier fiber, attenuator fiber) significant attenuation change of optical fiber is undesirable. We disclose that such change can be substantially eliminated by provision of hydrogen gettering material and/or a "hermetic" fiber coating. It is currently preferred to provide silica cladding material that is a hydrogen getter, and also provide a "hermetic" fiber coating. Containment of the fiber, together with a quantity of a gettering material (e.g., ErFe.sub.2) in an essentially hermetic enclosure is also disclosed.