Abstract: Improved lumped Raman amplification systems are disclosed. A lumped Raman amplification structure provides optimized efficiency, low noise figure over a range of gain settings, and a high saturation threshold. Responsibility for amplifying different portions of the spectrum is divided among multiple stages. In one particular implementation, two outer stages amplify a first band and two inner stages amplify a second band. The two inner stages also apply a small amount of amplification to the first band. A modification improves noise figure in the second band by adding some amplification in the second band to the first stage.

Abstract: Improved lumped Raman amplification systems are disclosed. A lumped Raman amplification structure provides optimized efficiency, low noise figure over a range of gain settings, and a high saturation threshold. Responsibility for amplifying different portions of the spectrum is divided among multiple stages. In one particular implementation, two outer stages amplify a first band and two inner stages amplify a second band. The two inner stages also apply a small amount of amplification to the first band. A modification improves noise figure in the second band by adding some amplification in the second band to the first stage.

Abstract: An amplification architecture for WDM receiver systems. The WDM channel grid is divided into groups of adjacent channels. A separate optical amplifier is provided for each channel with a single pump being shared among the channels of each group. The gain experienced by channels of a given group may be adjusted by varying the power of the group's pump. This approach allows equalization of received channel power such that all channels fall within the desired dynamic range. The amplification architecture may be implemented in a space-efficient manner at low cost.

Abstract: An approach for automatic Raman gain and tilt control for a WDM (Wavelength Division Multiplexing) optical communication systems is disclosed. An optical fiber carries a plurality of optical signals, in which at least one of the optical signals are reference signals. An optical gain unit (e.g., Raman pump unit) couples to the optical fiber and adjusts the reference signals to compensate, in part, for losses associated with the optical fiber and gain tilt accumulation. Upon detecting and analyzing the reference signals, a controller controls the optical gain unit and outputs a control signal to the optical gain unit based upon the analyzed reference signals. An optical amplifier is connected to the optical fiber and amplifies the optical signals. The optical gain unit provides a nearly constant power per channel at an input of the optical amplifier.

Abstract: An amplification architecture for WDM receiver systems. The WDM channel grid is divided into groups of adjacent channels. A separate optical amplifier is provided for each channel with a single pump being shared among the channels of each group. The gain experienced by channels of a given group may be adjusted by varying the power of the group's pump. This approach allows equalization of received channel power such that all channels fall within the desired dynamic range. The amplification architecture may be implemented in a space-efficient manner at low cost.

Abstract: A pump device to couple a pump radiation to an active optical fiber adapted to amplify optical signals, includes a first optical coupler (150) that optically couples a first fraction of the pump radiation (145) to the active fiber (130) and has an insertion loss for the optical signals less than or equal to 0,2 dB; and a second optical coupler (160) that is optically coupled to the first coupler (150) to receive from the first coupler (150) a second fraction of the pump radiation, that is further optically coupled to the active fiber (130) for feeding to the active fiber (130) at least part of the second fraction of the pump radiation and that has a coupling efficiency for the pump radiation of at least 70%.