In optics, it is said that The gain bandwidth and gain flatness of Amplifiers are enhanced utilizing gain control techniques.What techniques are they referring to ?
I know the automatic volume control (AVC) used in electrical circuits. But I dont believe it is the same in optics. Do someone know about these techniques ?
excerp1 : An erbium doped fiber amplifier with automatic gain control was designed using the all-optical gain control technique.
Reference : https://link.springer.com/chapter/10.1007/978-3-540-27824-5_97
by J Oliveira
excerp2: In optimization part, the optimum pump power for both SHFA and PHFA has been determined in which, wider gain bandwidth within 3–dB and higher average gain level can be obtained. Both of the gain bandwidth and gain flatness of the single–pass PHFA were enhanced utilizing the gain control technique. The average gain level and the pumppower conversion efficiency were improved by using the double–pass PHFA.
reference:design and development of wideband hybrid raman/edfa fiber amplifier
author : MUDHAFAR HUSSEIN ALI