Abstract: There is described a method of use of a mass exchanger. In the method the mass exchanger comprises: a first channel for accommodating flow of a liquid to be treated; and a second channel for accommodating flow of a treatment agent, the first and second channels have a permeable membrane provided between them, so as to allow transfer of selected species between the first channel and the second channel. The steps of the mass transfer method comprise passing the liquid to be treated along the first channel and introducing a mixture of liquid and gas into the second channel to provide a two-phase treatment agent. It is desirable to provide a means of adjusting the concentration of gas species in a liquid such as blood, while simultaneously controlling the temperature of the liquid and optionally adjusting the concentration of ionic and/or dissolved species in that liquid. By this method and mass exchanger providing a two-phase treatment agent, it is possible to simultaneously deliver gaseous species (e.g.

Abstract: There is described a method of use of a mass exchanger. In the method the mass exchanger comprises: a first channel for accommodating flow of a liquid to be treated; and a second channel for accommodating flow of a treatment agent, the first and second channels have a permeable membrane provided between them, so as to allow transfer of selected species between the first channel and the second channel. The steps of the mass transfer method comprise passing the liquid to be treated along the first channel and introducing a mixture of liquid and gas into the second channel to provide a two-phase treatment agent. It is desirable to provide a means of adjusting the concentration of gas species in a liquid such as blood, while simultaneously controlling the temperature of the liquid and optionally adjusting the concentration of ionic and/or dissolved species in that liquid. By this method and mass exchanger providing a two-phase treatment agent, it is possible to simultaneously deliver gaseous species (e.g.

Abstract: An optical sensor comprises at least one bundle comprising a plurality of optical fibers and a plurality of separate fluid-tight longitudinally extending ducts; and fluid connectors for introducing fluids selectively into at least some of said ducts. Test cells are formed (a) by array members with a pattern of holes or recesses applied to the end of the bundle, or sandwiched between the ends of two bundles or (b) within the fibers in cases where a duct overlaps with the optical field of the fiber. Usually others of the ducts serve to remove fluid from the test cells.

Abstract: An optical link comprises a first optical amplifier having a first gain spectrum with a first gain ripple and a second optical amplifier having a second gain spectrum with a second gain ripple. A combined gain spectrum of the first and second gain spectra is substantially flat and has a gain ripple that is substantially less than either the first gain ripple or the second gain ripple over a particular wavelength range.

Abstract: An optical fiber amplifier system includes an optical fiber adapted for use as an optical wave guide amplifier, and at least one optical pump optically coupled into the optical amplifier, wherein the pump receives both a DC electrical input and an AC electrical input, and wherein the pump provides an optical pump power to the optical fiber having both a DC optical power component and an AC optical power component. The optical fiber amplifier system also includes an optical pump power detector optically coupled to the pump, and at least one controller operatively connected to the pump power detector to determine the DC optical power component of the optical pump power, and wherein the controller adjusts the DC electrical input to the pump based on the DC optical power component.

Abstract: A Raman fiber amplifier includes: a transmission fiber; at least one optical pump providing optical pump power to the transmission fiber; and at least one pump power detector; at least one signal detector detecting signal power propagating through the transmission fiber. The Raman fiber amplifier also includes a controller that adjusts the pump power provided by the pump to adjust, gain, or signal power provided by this Raman fiber amplifier.

Abstract: An optical link comprises a first optical amplifier having a first gain spectrum with a first gain ripple and a second optical amplifier having a second gain spectrum with a second gain ripple. A combined gain spectrum of the first and second gain spectra is substantially flat and has a gain ripple that is substantially less than either the first gain ripple or the second gain ripple over a particular wavelength range.

Abstract: A hybrid optical signal amplifier is provided which includes the combination of a Raman amplifier and an EDFA assembly. The Raman amplifier has an output defined by regions of higher and lower gain levels, and the EDFA assembly has an output having a region, near the longer wavelengths thereof, that includes a maximum noise figure. The spectrum region of higher gain level of the Raman amplifier is selected to correspond to the spectrum region of the EDFA assembly that includes the maximum noise figure in order to lower the maximum noise figure of the resulting optical signal amplifier, as well as to flatten the gain across the output spectrum.

Abstract: An amplifier system includes: (i) a distributed Raman fiber amplifier and; (ii) a discrete Raman fiber amplifier that includes dispersion compensated fiber. The discrete Raman fiber amplifier is operatively connected to the distributed Raman fiber amplifier and amplifies signals received from the distributed Raman fiber amplifier. In one embodiment, at least one source of pump signal is coupled to the distributed and to the discrete Raman fiber amplifier. The distributed Raman fiber amplifier and the discrete Raman fiber amplifier in this embodiment share optical pump power provided by the shared pump. In one embodiment of the present invention an Erbium doped fiber amplifier (EDFA) is operatively connected to a discrete Raman fiber amplifier and the Erbium dope fiber amplifier amplifies signals received from the discrete Raman fiber amplifier.

Abstract: A hybrid optical signal amplifier is provided which includes the combination of a Raman amplifier and an EDFA assembly. The Raman amplifier has an output defined by regions of higher and lower gain levels, and the EDFA assembly has an output having a region, near the longer wavelengths thereof, that includes a maximum noise figure. The spectrum region of higher gain level of the Raman amplifier is selected to correspond to the spectrum region of the EDFA assembly that includes the maximum noise figure in order to lower the maximum noise figure of the resulting optical signal amplifier, as well as to flatten the gain across the output spectrum.

Abstract: Disclosed is a dispersion compensating optical regenerator that provides for enhanced performance of telecommunication systems employing varying-soliton signal propagation and dispersion compensation. Allowing the solitons to change in amplitude, width and shape while traversing the dispersion compensating optical regenerator provides for beneficial system performance including improved signal to noise ratio at the receiver, reduced impact of signal interactions, and longer regenerator spacing. The regenerator in accord with the invention combines the filtering features of a NOLM or NALM with the advantageous effects of dispersion compensation.

Abstract: Disclosed is a dispersion compensating optical regenerator that provides for enhanced performance of telecommunication systems employing varying-soliton signal propagation and dispersion compensation. Allowing the solitons to change in amplitude, width and shape while traversing the dispersion compensating optical regenerator provides for beneficial system performance including improved signal to noise ratio at the receiver, reduced impact of signal interactions, and longer regenerator spacing. The regenerator in accord with the invention combines the filtering features of a NOLM or NALM with the advantageous effects of dispersion compensation.

Abstract: A method for upgrading bandwidth in a fiber optic system utilizing Raman amplification and having an initial band capacity provided by a plurality of pumps including the steps of identifying a fiber optic system to be upgraded, activating at least one new pump in the fiber optic system necessary to provide upgraded band capacity to the fiber optic system while retaining the initial band capacity provided by the plurality of pumps, and adjusting power of at least one pump of the fiber optic system to minimize gain ripple or signal output ripple.

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: A method for upgrading bandwidth in a fiber optic system utilizing Raman amplification and having an initial band capacity provided by a plurality of pumps including the steps of identifying a fiber optic system to be upgraded, activating at least one new pump in the fiber optic system necessary to provide upgraded band capacity to the fiber optic system while retaining the initial band capacity provided by the plurality of pumps, and adjusting power of at least one pump of the fiber optic system to minimize gain ripple or signal output ripple.

Abstract: A soliton pulse generator is formed by providing an input continuous wave, stimulating Brillouin scattering of an input wave having a frequency determined by the frequency of the input continuous wave to generate a backscattered wave, coupling a continuous wave having a frequency determined by the input continuous wave with the backscattered wave to generate a sinusoidal output signal, and then compressing the sinusoidal output to form a soliton pulse train. Because the wavelength shift of the backscattered wave is essentially independent of the input wavelength and power, coupling of the second wave and the backscatterred wave results in a highly stable and controllable sinusoidal output signal. A highly stable and controllable soliton pulse train is provided by compressing the sinusoidal signal with use of a dispersion decreasing fiber or with use of an alternative pulse compressing device.

Abstract: An optical fiber amplifier system includes an optical fiber adapted for use as an optical wave guide amplifier, and at least one optical pump optically coupled into the optical amplifier, wherein the pump receives both a DC electrical input and an AC electrical input, and wherein the pump provides an optical pump power to the optical fiber having both a DC optical power component and an AC optical power component. The optical fiber amplifier system also includes an optical pump power detector optically coupled to the pump, and at least one controller operatively connected to the pump power detector to determine the DC optical power component of the optical pump power, and wherein the controller adjusts the DC electrical input to the pump based on the DC optical power component.

Abstract: A system for measuring polarization mode dispersion (PMD) in a fiber using a polarizer controlling the polarization state of light input to the fiber and a polarization analyzer measuring the polarization state of light output from the fiber. Jones matrix analysis is applied to data derived from three input polarization states and two wavelengths of probing radiation. Performance is improved by using incoherent light sources such as light emitting diodes in conjunction with two bandpass filter. However, a laser source and optical detector are used to align the fiber. The system is particularly useful in measuring PMD values in short lengths of fiber and mapping those values with a long fiber from which the test fiber was cut. Preferably, the PMD is measured for various values of twist experimentally induced in the test fiber, and the short-length PMD value is that associated with zero-internal twist in the fiber as calculated according to a model. The fiber may also be loaded during measurement.

Abstract: A unitary dispersion managed waveguide fiber with distributed amplification and a system incorporating the waveguide fiber are disclosed. Total dispersion along the waveguide fiber changes from positive to negative along the length of the waveguide over a transmission wavelength range. Distributed amplification is provided by stimulated emission of a dilute concentration of a rare earth dopant in the waveguide, by Raman effects or by both.

Abstract: A system for measuring polarization mode dispersion (PMD) in a fiber using a polarizer controlling the polarization state of light input to the fiber and a polarization analyzer measuring the polarization state of light output from the fiber. Jones matrix analysis is applied to data derived from three input polarization states and two wavelengths of probing radiation. Performance is improved by using incoherent light sources such as light emitting diodes in conjunction with two bandpass filter. However, a laser source and optical detector are used to align the fiber. The system is particularly useful in measuring PMD values in short lengths of fiber and mapping those values with a long fiber from which the test fiber was cut. Preferably, the PMD is measured for various values of twist experimentally induced in the test fiber, and the short-length PMD value is that associated with zero-internal twist in the fiber as calculated according to a model. The fiber may also be loaded during measurement.