Lucent Technologies Inc.

Alcatel-lucent USA Inc.

Bernd Teichmann

Dieter Werner

Jianhui Zhou

Peter Johannes Winzer

Lothar Benedict Erhard Josef Moeller

Steffen Reichel

Andreas Benz

Dirk Bode

Matthias Richard Feulner

Guido Hermann Hunziker

Bianca Buchold

A bandstop filter method and system for suppressing ASE noise is disclosed. In one embodiment of the bandstop filter system, there is provided a first switch, having an input port for receiving an optical signal, and two output ports; a bandstop filter coupled to a first of the two output ports of the first switch; and a second switch, having two input ports and one output port, wherein a first of the two input ports of the second switch is coupled to the bandstop filter and a second of the two input ports of the second switch is coupled to a second of the two output ports of the first switch.

Method and system for suppressing ASE noise

Raman amplification is used in optical transmission systems, devices and/or components way of for applying Raman amplification avoiding or suppressing detrimental and hence undesirable non-linear effects is provided. Raman amplification in an optical device is provided by firstly determining a pump power () necessary for providing Raman amplification and then by providing a low spectral power density by pumping the optical device with pump power () at a relatively broad pump power spectrum and preferably a low spectral pump power amplitude such that the total output pump power () remains sufficiently high. The pump power () is optically attenuated prior to being coupled to the optical device.

Method and contrivance for applying a Raman amplification in a transmission and/or fibre device

The present invention generally relates to the field of optical transmission and particularly to a method and an apparatus for controlling the optical power of an optical transmission signal in a wavelength division multiplex optical transmission system (WDM system). The optical power of a control channel is controlled to keep the total optical power of the optical transmission signal constant. The present invention avoids the deleterious effects of stimulated Brillouin Scattering by spreading the power density spectrum of the optical control signal.

Method and apparatus for controlling the optical power of an optical transmission signal

In an optically amplified wavelength division multiplexed (WDM) system having a WDM signal comprising a plurality of optical channels, the per-channel gain of the optical channels is kept relatively constant despite changes in input power at the optical amplifier, such as when individual optical channels of the WDM signal are added and dropped. More specifically, gain of an optical amplifier is controlled by controlling the amount of pump power supplied to the optical amplifier as a function of changes in input power which are measured in a feed-forward monitoring path. The amount of pump power for effecting gain control is adjusted according to a scaled relationship to the measured input power of the optical amplifier. By controlling the pump power directly in response to changes in input power, gain of the optical amplifier can be controlled within a sub-microsecond time scale from the time that a change in input power is detected. Moreover, by maintaining relatively constant per-channel gain in an amplified WDM signal despite changes in input power at the optical amplifier, power excursions are substantially reduced in surviving optical channels of the WDM signal, i.e., those at the output of the optical amplifier.

Fast gain control for optical amplifiers

The present invention relates generally to the field of optical transmission and particularly to a method and a system for controlling optical amplification in wavelength division multiplex optical transmission. WDM systems currently under development will have eighty or more channels, i.e., modulated optical signals with different wavelengths (known as Dense Wavelength Division Multiplexing, DWDM). These DWDM systems are demanding optical amplifiers which, especially considering the cascadation of a plurality of optical amplifiers along the transmission path of the DWDM system, have only very limited tolerances in certain parameters. Among these parameters gain flatness and gain tilt are of special importance. The present invention discloses a method and a system which make use of auxiliary optical signals having a given power level which is equal for all auxiliary signals. Differences in the power levels of the auxiliary signals after optical amplification are used for the control of the optical amplifiers of the WDM system.

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Eckental, Germany

Bernd Teichmann