Abstract: An amplifier system includes: (i) a distributed Raman fiber amplifier adapted to amplify C and L-band signals and; (ii) a discrete Raman fiber amplifier module that includes a C-band amplification stage and an L-band amplification stage. The discrete Raman fiber amplifier module is operatively connected to the distributed Raman fiber amplifier and amplifies signals received from the distributed Raman fiber amplifier. In one embodiment the distributed Raman fiber amplifier and the discrete Raman fiber amplifier share optical pump power provided by the shared pump.

Abstract: A pulse-reshaping optical fiber having a core with refractive index nc surrounded by a cladding layer, the diameter of the core changing monotonically along the length of the fiber. The core includes a central region having a maximum refractive index n1 and a moat region disposed radially adjacent to the central region. The moat region has a minimum refractive index n2 which is sufficiently low that the index delta &Dgr;2 of the moat region with respect to nc is not greater than −0.1%. The moat region affects the change in dispersion with respect to fiber cladding diameter, as well as providing the pulse-reshaping fiber with low dispersion versus wavelength slope. The pulse-reshaping fiber is particularly useful in association with optical transmission systems where high transmission rates and narrow pulse widths are desired, including components such as high pulse rate wavelength-division-multiplexers (WDMs) and optical regenerators.

Abstract: A nonlinear optical loop mirror is combined with a pulse compressor. The nonlinear loop mirror receives both control pulses and data pulses and further transmits selected data pulses in accordance with relative amounts of overlap between individual control and data pulses. The pulse compressor compresses at least one of the control and data pulses for improving the transmission efficiency of the selected data pulses and reducing crosstalk with the remaining data pulses.

Abstract: A regulator for regulating outlet pressure of a fluid contained in a tank includes first and second pistons. The first piston is biased in a first direction and is movable against the bias when exposed to pressure in the tank. The second piston is biased in a second direction away from an end of the first piston, and the second piston is movable against the bias when exposed to the outlet pressure. The ends of the first and second pistons are separated by a first distance to allow the fluid to flow out of the tank, and the ends of the first and second pistons are positioned closer together than the first distance to inhibit flow out of the tank when the outlet pressure reaches a threshold.

Abstract: An optical fiber path in a light amplifying apparatus such as a ring laser, figure eight laser, or nonlinear optical loop mirror, comprises circularly birefringent fiber in order to generate twisted solitons. The light being amplified will follow the pitch of a principle axis of the circularly birefringent fiber as it passes through the optical fiber path. Gain from any other possible polarization lessens as the principle axis polarization constructively interferes upon each round trip. The resulting pulses should have a linear polarization everywhere and the plane of polarization should rotate as a function of space and time. Simultaneous generation of orthogonal, twisted solitons from a single fiber laser source may be accomplished by not placing an optical isolator in the fiber laser optical path.

Abstract: An optical fiber preform is made by supplying the base glass reactant and the dopant glass reactant to a burner that generates a flame in which a stream of glass particles is produced. The burner moves with respect to a rotating mandrel to deposit layers of glass particles on the mandrel. During the deposition of a portion of the preform, the flow rate of the dopant glass reactant is varied in accordance with a first recipe of dopant flow as a function of burner position as the burner moves longitudinally along the substrate to form one of the layers. The flow rate of the dopant glass reactant varies in accordance with a second recipe of dopant flow as a function of burner position as the burner moves longitudinally along the substrate to form a layer adjacent to the one layer. The second recipe is different from the first recipe, and the flow rate of the dopant glass reactant changes during the step of moving the reaction zone to form the one layer.

Abstract: A single mode optical fiber suitable for use in an amplified fiber optic system which includes an inner glass core doped with a rare earth element and an outer transparent glass cladding. The fiber exhibits a plurality of mode coupling sites formed at regular intervals along the length of the fiber which provides for a reduced DOP. The sites are formed by a twist at regular intervals along the fiber length by applying a torque to the fiber. The method of forming the fiber is also disclosed.

Abstract: A nonlinear optical loop mirror device having a distributed directional asymmetry. A dispersion decreasing optical fiber is formed into a loop by an optical coupler which divides input pulses into two component pulses that propagate around the loop in opposite directions, and which transmits and/or reflects returning component pulses in accordance with their relative phases. The parameters of the loop, such as its length, effective area, rate of change of dispersion, etc. are selected so that input pulses may be switched or transmitted in accordance with whether their widths or amplitudes are above or below predetermined threshold values.

Abstract: A single mode optical fiber suitable for use in an amplified fiber optic system which includes an inner glass core doped with a rare earth element and an outer transparent glass cladding. The fiber exhibits a plurality of mode coupling sites formed at regular intervals along the length of the fiber which provides for a reduced DOP. The sites are formed by a twist at regular intervals along the fiber length by applying a torque to the fiber. The method of forming the fiber is also disclosed.

Abstract: A nonlinear optical loop mirror device having a distributed directional asymmetry. A dispersion decreasing optical fiber is formed into a loop by an optical coupler which divides input pulses into two component pulses that propagate around the loop in opposite directions, and which transmits and/or reflects returning component pulses in accordance with their relative phases. The parameters of the loop, such as its length, effective area, rate of change of dispersion, etc. are selected so that input pulses may be switched or transmitted in accordance with whether their widths or amplitudes are above or below predetermined threshold values.

Abstract: A nonlinear optical loop mirror device having a distributed directional asymmetry. A dispersion decreasing optical fiber is formed into a loop by an optical coupler which divides input pulses into two component pulses that propagate around the loop in opposite directions, and which transmits and/or reflects returning component pulses in accordance with their relative phases. The parameters of the loop, such as its length, effective area, rate of change of dispersion, etc. are selected so that input pulses may be switched or transmitted in accordance with whether their widths or amplitudes are above or below predetermined threshold values.

Abstract: An apparatus is disclosed for interrupting operation of a starter of an alternatively-fueled motor vehicle. The apparatus comprises a fuel receptacle, a cover and a switch. The fuel receptacle has an electrically conductive, grounded fill opening. The cover mates with the fill opening of the fuel receptacle, and has a contact sensor which generates a ground signal indicative of contact between the cover and the fill opening. The switch communicates with the contact sensor and with the starter, and interrupts operation of the starter when no signal indicative of contact is received from the contact sensor.

Abstract: Intrapulse Raman scattering is utilized in providing optical devices that can be adapted to perform various logic and switching functions. In a logic gate embodiment of the present invention, a plurality of pulses of the same central wavelength are coupled to produce an output pulse having a power level equal to the sum power level of the inputs. When the power level of a sufficiently narrow output pulse exceeds the Raman threshold, the output pulse experiences a wavelength shift of a magnitude that can be controlled by adjusting the input power. An optical filter selectively blocks coupler output pulses depending on the desired logical operation of the device. In a switch according to the invention, an input pulse and a control pulse are coupled, and Raman scattering of the output pulse is stimulated. The output pulse is applied to several output lines, each having a filter centered at a predetermined pass band.

Abstract: A combination of dispersion flattened single mode optical waveguide fiber and soliton signal pulses yields an optimum telecommunication system capacity. The dispersion flattened fiber serves to relax tolerances on soliton center wavelength and intensity. In addition, the inventive combination facilitates the design and use of long haul systems using optical amplifiers.

Abstract: A single-mode optical fiber suitable for the transmission of solitons has a refractive index profile that changes along the length of the fiber to provide a fiber dispersion that monotonically decreases along the fiber from one end thereof to the other. The fiber includes a core of maximum refractive index n.sub.1 and a radius a, surrounded by cladding material having a refractive index n.sub.2 which is less than n.sub.1. The fiber core includes a central region that extends to the longitudinal axis of the fiber and an outer region, the inner and outer regions being separated by a region of depressed refractive index. The inner radius a.sub.1 of the region of depressed refractive index is greater than zero and the maximum radius a.sub.o of the region of depressed refractive index is less than a.