Optical system for gain equalization

摘要

A system for individually controlling the power levels of a plurality of wavelength division multiplexed (WDM) optical signals in a single optical guide comprising optical attenuation means comprising a plurality of individually controllable optical attenuators. An example of a suitable optical attenuator is a tunable fibre Bragg grating filter whose reflectivity characteristic varies with wavelength over an active region thereof. By tuning the filter, it is possible to control the reflectivity at a particular wavelength in the active region. The system may, in addition, comprise a second plurality of optical attenuators arranged so as to compensate for any power level distortion introduced by the first plurality. Optical circulators may be used to route signals into and between the pluralities of optical attenuators.