Reduction of Power Fluctuation in Pulsed Lightwave Frequency Sweepers With SOA Following EDFA

A pulsed lightwave frequency sweeper is a frequency source with linear frequency scanning. It can be made using a fiber ring with an acoustooptic frequency shifter and an optical amplifier. The drawback of this sweeper, however, is optical power fluctuation that is attributable to power feedback to the erbium-doped fiber amplifier (EDFA) by the fiber ring. This study presents suppression of the fluctuation by tandem configuration of optical amplifiers, such as EDFA and semiconductor optical amplifiers in this order, in the fiber ring. The configuration was demonstrated experimentally and its noise performance was evaluated by changing the operation point of the amplifiers