Abstract: An optical amplifier assembly for submarine applications. The optical amplifier assembly comprises: a first and a second double stage fiber amplifier with respective first and second fiber amplifiers for amplifying optical signals (OS, OS?) each propagated on a respective optical fibre, said optical fibres being operated in opposite operating directions (W-E, E-W), and a common pump source comprising a plurality of pump light sources, the common pump source being coupled via a coupler as a co-propagating pump to the first and second fiber amplifiers of the first and second double stage fiber amplifiers. The proposed optical amplifier assembly further comprises a gain flattening filter between the two fiber amplifiers of the first and second double stage fiber amplifiers. Thus the proposed optical amplifier assembly presents an increased efficiency with respect to an output power at a constant pump power and allows to adjust the pump power for maintaining a given output power without excessive NF degradation.

Abstract: The amplifying optical fiber comprises a single-mode core and a multimode core surrounding the single-mode core, the multimode core containing a doped layer referred to as a “doped ring” and having a certain concentration of active rare earth ions to perform amplification by active rare earth ions on at least one optical signal for injection into the amplifying fiber. The fiber is dimensioned so that the product of its length multiplied by its Raman efficiency is greater than or equal to 0.5 W?1. In addition, the fiber presents absorption defined by an absorption coefficient expressed in dB/m, which absorption presents, at a certain wavelength, a maximum value referred to as the “absorption maximum”, the fiber presents accumulated absorption, corresponding to the product of its length multiplied by the absorption maximum, that is greater than or equal to 100 dB. The invention also provides an amplifier including such a fiber, a single-mode pump, and a multimode pump.

Abstract: The amplifying optical fiber (1) comprises a single-mode core (10) and a multimode core (20) surrounding the single-mode core, the multimode core containing a doped layer referred to as a “doped ring” (21) and having a certain concentration of active rare earth ions (6) to perform amplification by active rare earth ions on at least one optical signal for injection into the amplifying fiber. The fiber is dimensioned so that the product of its length multiplied by its Raman efficiency is greater than or equal to 0.5 W?1. In addition, the fiber presents absorption defined by an absorption coefficient expressed in dB/m, which absorption presents, at a certain wavelength, a maximum value referred to as the “absorption maximum”, the fiber presents accumulated absorption, corresponding to the product of its length multiplied by the absorption maximum, that is greater than or equal to 100 dB. The invention also provides an amplifier including such a fiber, a single-mode pump, and a multimode pump.

Abstract: WDM optical signals are amplified using optical parametric amplification by applying an appropriate separation of those optical signals according to their carrier angular frequencies. These angular frequencies are within the two principal amplification bands defined by the non-linear optical medium used for optical parametric amplification. It is advantageously proposed to launch into the non-linear optical medium in one direction the optical signals of carrier frequencies within the one amplification band, and in the opposite counter-propagating direction the optical signals of carrier angular frequencies within the other amplification band. The required pump radiation is launched co-linearly with the respective optical signals to be amplified.

Abstract: The invention consists in an amplifying optical fiber comprising a core containing a dopant and a cladding, wherein said core comprises a monomode core intended to propagate an optical signal, quantum dots of a semiconductor material being disposed in or near said monomode core, and a multimode core surrounding the monomode core, intended to receive a pumping signal.

Abstract: An optical amplification unit comprises at least one optical amplifier for amplifying an optical signal and a filter preceding or following the optical amplifier. The optical amplifier comprises a first measuring device for measuring a property of an input signal of the optical amplifier, a second measuring device for measuring a property of an output signal of the optical amplifier, and a control circuit for controlling a gain characteristic of the optical amplifier in dependence of said input and output signal properties. The filter exhibits a wavelength-dependent attenuation of the optical signal. The optical amplification unit is connectable to an optical fiber span and the filter is adapted to compensate for a span loss tilt caused by said optical fiber span. An optical transmission system with at least one such optical amplification unit and corresponding methods.

Abstract: An optical amplifier assembly for submarine applications. The optical amplifier assembly comprises: a first and a second double stage fibre amplifier with respective first and second fibre amplifiers for amplifying optical signals (OS, OS') each propagated on a respective optical fibre, said optical fibres being operated in opposite operating directions (W-E, E-W), and a common pump source comprising a plurality of pump light sources, the common pump source being coupled via a coupler as a co-propagating pump to the first and second fibre amplifiers of the first and second double stage fibre amplifiers. The proposed optical amplifier assembly further comprises a gain flattening filter between the two fibre amplifiers of the first and second double stage fibre amplifiers. Thus the proposed optical amplifier assembly presents an increased efficiency with respect to an output power at a constant pump power and allows to adjust the pump power for maintaining a given output power without excessive NF degradation.

Abstract: In a network management system for an optical network, wherein the optical network comprises at least one optical fiber line (1) for transmitting an optical signal having a plurality of optical amplifiers (2) and the network management system comprises a central management unit (5) for controlling the optical amplifiers (2), the management unit (5) periodically determines the output power (Pout) of each optical amplifier (2) taking into account noise power and signal power of the optical signal, and subsequently sets the output power (Pout) of each optical amplifier (2) to a target output power so that at least the signal power at an output end (7) of the fiber line (2) is set to a predetermined value.

Abstract: An optical amplification system is described which comprises an optical amplifier and an optical filter. The gain of the optical amplifier is changeable to different gain values. For every one of the gain values, a wavelength-dependent gain curve exists. At least for one of the gain values, the gain curve varies over the wavelength. An apodized long-period grating (LPG) is used as the optical filter. The apodized LPG provides at least one wavelength-dependent attenuation curve which compensates the gain curve varying over the wavelength.

Abstract: A fiber optical system (1) for transmitting an optical signal comprises an optical fiber line (2) with a plurality of optical fiber spans (3) interconnected by a plurality of optical amplifiers (4). Each optical amplifier (4) comprises: At least one variable optical attenuator (5) generating a gain tilt of the amplification of the optical signal, a Raman tilt determining device (6) for determining a Raman tilt induced in the fiber span (3) following the optical amplifier (4), and a dynamic controller (7) connected to the variable optical attenuator (5) and to the Raman tilt determining device (6) adjusting the gain tilt such that the Raman tilt is compensated for.

Abstract: The invention discloses an optical amplifier (18) that amplifies signal light in a signal band in a fiber optic transmission system (10) having at least first and second optically pumped signal light gain amplifying stages (30), a tilt controller (40) linked to a control unit, a optical monitor (34) analyzing signal powers, characterized in that the amplified spontaneous emission of the optical amplifier (18) is measured at two extreme wavelengths of the signal band to derive control signals (44) for at least the tilt controller (40).

Abstract: An optical fiber amplifier is considered comprising a mono-mode core, a first cladding around said core and at least a further cladding around said first cladding while said first cladding includes a ring shaped active region doped with rare earth material surrounding said mono-mode core. Advantageously, the first cladding is designed with a radial refractive index following an almost continuous decreasing function for increasing radius. The use of a continuously decreasing refractive index for the cladding at the outer border of the ring shaped active medium optimize the efficiency of the coupling between the core and the cladding.

Abstract: An Optical transmission system (10) is presented that comprises at least one transmitter (12), at least one transmission line (14), at least one optical fiber amplifier (18), and at least one receiver (21), the optical fiber amplifier (18) being designed to show a flat characteristic of output power versus wavelength. The optical fiber amplifier (18) is designed to show the flat output characteristic in response to a flat characteristic of a first input power level versus wavelength. At least one coupler (28) for coupling at least one Raman amplifier (30) to the optical transmission system (10) is provided, the Raman amplifier (30) having a Raman gain that is tilted in a direction opposite to a tilt of the optical fiber amplifier (18) that would occur in response to a flat characteristic of a second input power level versus wavelength. Thereby, an optical transmission system (10) is presented that can be upgraded to improve OSNR while maintaining a flat output characteristic.

Abstract: It is proposed to amplify WDM optical signals using optical parametric amplification by apply an appropriate separation of those optical signals according to their carrier angular frequencies. These angular frequencies are within the two principle amplification bands defined by the used non-linear optical medium for optical parametric amplification. It is advantageously proposed to launch into the non-linear optical medium in one direction the optical signals of carrier frequencies within the one amplification band and in the opposite counter-propagating direction the optical signals of carrier angular frequencies within the other amplification band. The required pump radiation is being launched co-linearly with the respective optical signals to be amplified.

Abstract: The invention relates to the field of amplifying or emitting optical fibers. It comprises an amplifying optical fiber doped with a rare earth comprising a plurality of successive segments (1, 2, 3, 4, 5), presenting a monomode core and a multimode core, presenting at the periphery of the multimode core a peripheral segment (4) of low index so as to increase the numerical aperture of the optical fiber, outer cladding (5) being situated at the periphery of the low index peripheral segment (4), the multimode core being at least in part above the outer cladding (5), the peripheral segment (2) presenting a decreasing gradient shape.

Abstract: The invention relates to the field of amplifying or emitting optical fibers. It comprises an amplifying optical fiber doped with a rare earth comprising a plurality of successive segments (1, 2, 3, 4, 5), presenting a monomode core and a multimode core, presenting at the periphery of the multimode core a peripheral segment (4) of low index so as to increase the numerical aperture of the optical fiber, outer cladding (5) being situated at the periphery of the low index peripheral segment (4), the multimode core being at least in part above the outer cladding (5), the peripheral segment (2) presenting a decreasing gradient shape.

Abstract: The invention discloses an optical amplifier (18) that amplifies signal light in a signal band in a fiber optic transmission system (10) having at least first and second optically pumped signal light gain amplifying stages (30),

Abstract: The amplifying optical fiber (1) comprises a single-mode core (10) and a multimode core (20) surrounding the single-mode core, the multimode core containing a doped layer referred to as a “doped ring” (21) and having a certain concentration of active rare earth ions (6) to perform amplification by active rare earth ions on at least one optical signal for injection into the amplifying fiber. The fiber is dimensioned so that the product of its length multiplied by its Raman efficiency is greater than or equal to 0.5 W−1. In addition, the fiber presents absorption defined by an absorption coefficient expressed in dB/m, which absorption presents, at a certain wavelength, a maximum value referred to as the “absorption maximum”, the fiber presents accumulated absorption, corresponding to the product of its length multiplied by the absorption maximum, that is greater than or equal to 100 dB.

Abstract: An Optical transmission system (10) is presented that comprises at least one transmitter (12), at least one transmission line (14), at least one optical fiber amplifier (18), and at least one receiver (21), the optical fiber amplifier (18) being designed to show a flat characteristic of output power versus wavelength. The optical fiber amplifier (18) is designed to show the flat output characteristic in response to a flat characteristic of a first input power level versus wavelength. At least one coupler (28) for coupling at least one Raman amplifier (30) to the optical transmission system (10) is provided, the Raman amplifier (30) having a Raman gain that is tilted in a direction opposite to a tilt of the optical fiber amplifier (18) that would occur in response to a flat characteristic of a second input power level versus wavelength. Thereby, an optical transmission system (10) is presented that can be upgraded to improve OSNR while maintaining a flat output characteristic.

Abstract: An optical fiber amplifier is considered comprising a mono-mode core, a first cladding around said core and at least a further cladding around said first cladding while said first cladding includes a ring shaped active region doped with rare earth material surrounding said mono-mode core. Advantageously, the first cladding is designed with a radial refractive index following an almost continuous decreasing function for increasing radius. The use of a continuously decreasing refractive index for the cladding at the outer border of the ring shaped active medium optimize the efficiency of the coupling between the core and the cladding.