ERBIUM-DOPED FIBRE AMPLIFIER WITH SHAPED SPECTRAL GAIN

摘要

The characteristics of spectral gain of a doped fiber amplifier with erbium has been modified by introducing a gain modifying amplifier in the filter. The filter is selected to modify the natural gain spectrum of the amplifier in order to suppress the peak of the gain and thus flatten the general profile of the spectral gain. As the amplifier is distributed, it is possible to insert one or more filter (s) along the length of the fiber. It is shown that there are considerable advantages in placing the filter on the length of the amplifier rather than the end of it, which would seem the most appropriate place. These advantages are the fact that the pump efficiency of the amplifier is hardly affected and saturation flow of power is similar to the untrained amplifier. In addition, the flat spectral gain provides an ideal amplifier for use in a number of lengths of signal waves, as required for division multiplexing wavelengths (WDM). The invention therefore includes both the concept of filtering to modify the shape of the gain of the amplifier response and the discovery that this can be accomplished without disadvantage if placed carefully one or more filters on the length of the amplifier.