Optical signal equalizer for wavelength division multiplexed optical fiber systems
AssigneeGTE Laboratories Incorporated
InventorRobert Olshansky
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Abstract
This invention disclosure describes the application of a polarization insensitive acoustically-tuned optical filter used in a multichannel WDM system to equalize variations in the power level of the WDM channels. The invention also describes a simple means for providing a low frequency control system which enables the equalizer to determine the signal levels of N optical carriers prior to equalizing the signals.
Claims7
Apparatus in a communication system for controlling the level of a multiplexed optical signal composed of a plurality of amplified optical signals Si where i is a number denoting one of the plurality of optical signals at an individual frequency fi comprising:
- tap means for tapping said multiplexed optical signal to produce a tapped multiplexed optical signal;
- means for converting said tapped multiplexed optical signal to demultiplexed electrical signals;
- control means having an input port for receiving said demultiplexed electrical signals, including a calculation means for calculating coefficients Xi at frequency fi
- filter means having an input port for receiving said input multiplexed optical signal, a first output port for transmitting a first output optical signal, and including a control port means for receiving said control signal;
- wherein the filter means responsive to the control signal attenuates the level of one or more of the individual optical signals S at the first output port according to the relation cos.sup.2 (.sqroot.Xi.pi./2).
The apparatus of claim I wherein the filter means is a polarization independent acoustically tuned optical filter.
Dependencies are inferred from the claim text.