Abstract: A method and apparatus for optical amplification with a large dynamic gain range in both the non-linear (1530-1540 nm) and linear (1540-1565 nm) regimes of the C-Band. The large dynamic gain range is achieved by the synergistic operation of a dual-stage Erbium-doped Fiber Amplifier (EDFA) having a self-saturating Thulium-doped fiber inserted between the two stages. The Thulium-doped fiber saturation is determined by the output power of the first EDFA stage, and the synergistic, combined operation of both EDFA stages and the self-saturating absorber is controlled by appropriate algorithms and software.

Abstract: A high efficiency, high performance optical amplifier includes an amplification stage comprised of two Erbium doped fiber (EDF) gain sections separated by a variable optical attenuator (VOA). A single pump serves to pump both EDF sections. A high dynamic gain range is achieved by an interplay between the action of the VOA, and the pump energy absorption mechanisms in each gain section, which are dominated by the saturation characteristics of each of the EDFs. In a preferred embodiment of the method, input signals are coupled with a pump signal into a first EDF gain section in which the energy absorption mechanisms provide first amplified signals that are correlated with a residual pump signal. At the first EDF gain section output, the combined amplified signals and residual pump signal are decoupled, the amplified signals being attenuated in the VOA while the residual pump signal being routed around the VOA.

Abstract: A method and apparatus for dynamically obtaining a substantially linear gain tilting of the output spectrum of an EDFA, in either automatic gain control or automatic power control modes. A necessary tilt is obtained while holding the total gain or total output power of the EDFA constant. The apparatus includes a variable mid-stage attenuator inserted between two (first and second) gain sections of the EDFA. The tilting is performed by ordering the attenuator to increase or decrease its attenuation in a value proportional to the tilting needed, while changing substantially simultaneously the pumping of the second gain section. The attenuation change process is based on the saturation mechanism of the erbium amplifier in the L-band, which translates the wavelength-independent loss of a variable optical attenuator into a linear wavelength-dependent gain at the EDFA output.

Abstract: An apparatus and method for a self-adjusting Raman amplifier for fiber optic transmission lines incorporating a line diagnostic mechanism in order to calculate, control and optimize the operating parameters for the amplifier. A Line Analyzing Unit, adjacent to the Raman pump unit, operates before the Raman pump is enabled and during operation, and characterizes the transmission line. The Line Analyzing Unit determines and characterizes the types of optical fibers installed along the transmission line and calculates and optimizes the pump or pumps power in order to achieve optimum gain, gain equalization and gain tilt. The Line Analyzing Unit may also determine if there is an optical loss or reflection in the optical fiber that can be destructive when the high power Raman pump is operating.

Abstract: A method and apparatus for optical amplification with a large dynamic gain range in both the non-linear (1530-1540 nm) and linear (1540-1565 nm) regimes of the C-Band. The large dynamic gain range is achieved by the synergistic operation of a dual-stage Erbium-doped Fiber Amplifier (EDFA) having a self-saturating Thulium-doped fiber inserted between the two stages. The Thulium-doped fiber saturation is determined by the output power of the first EDFA stage, and the synergistic, combined operation of both EDFA stages and the self-saturating absorber is controlled by appropriate algorithms and software.

Abstract: An apparatus and method for a self-adjusting Raman amplifier for fiber optic transmission lines incorporating a line diagnostic mechanism in order to calculate, control and optimize the operating parameters for the amplifier. A Line Analyzing Unit, adjacent to the Raman pump unit, operates before the Raman pump is enabled and during operation, and characterizes the transmission line. The Line Analyzing Unit determines and characterizes the types of optical fibers installed along the transmission line and calculates and optimizes the pump or pumps power in order to achieve optimum gain, gain equalization and gain tilt. The Line Analyzing Unit may also determine if there is an optical loss or reflection in the optical fiber that can be destructive when the high power Raman pump is operating.

Abstract: This invention is a dynamic gain equalizer for fiber optic communication systems with a spectral output that can be changed dynamically as needed by adjusting one or more variable power lasers providing optical pumping. The proposed dynamic gain equalizer can adjust power inequalities in WDM signals resulting from the gain properties of EDFA's. The dynamic gain equalizer uses erbium ions in a system that has not been pumped by a laser, or pumped only to a small extent, with the result that passing radiation can be absorbed by the erbium ion. For a given erbium doped fiber, with a given fiber length, the spectral absorption of the fiber is dependent on the signal power entering the erbium doped fiber for each of the signal wavelengths. In order to vary the absorption spectrum of the filter, the erbium doped fiber is pumped by a laser at a low power, to levels where the excited state population inversion either has not occurred or is insufficient to achieve total gain.

Abstract: This invention describes an apparatus and method for a self adjusting Raman amplifier for fiber optic transmission lines incorporating a line diagnostic mechanism in order to calculate, control and optimize the operating parameters for the amplifier. This need arises because the amplifier gain medium is the transmission line itself and the amplifier properties depend on the optical fiber properties along the first tens of kilometers of the transmission line from the pump. A Line Analyzing Unit, adjacent to the Raman pump unit, operates before the Raman pump is enabled and during operation, and characterizes the transmission line. The Line Analyzing Unit determines and characterizes the types of optical fibers installed along the transmission line and calculates and optimizes the pump or pumps power in order to achieve optimum gain and gain equalization.

Abstract: This invention describes an apparatus and method for a self adjusting Raman amplifier for fiber optic transmission lines incorporating a line diagnostic mechanism in order to calculate, control and optimize the operating parameters for the amplifier. This need arises because the amplifier gain medium is the transmission line itself and the amplifier properties depend on the optical fiber properties along the first tens of kilometers of the transmission line from the pump. A Line Analyzing Unit, adjacent to the Raman pump unit, operates before the Raman pump is enabled and during operation, and characterizes the transmission line. The Line Analyzing Unit determines and characterizes the types of optical fibers installed along the transmission line and calculates and optimizes the pump or pumps power in order to achieve optimum gain and gain equalization.