Experimental investigation of transients in six cascaded AGC EDFAs and their suppression using a high-speed VOA

Abstract

We investigate gain transient responses of an automatic gain control (AGC) EDFA with fast electrical feed-forward pump control. Even if each of the AGC EDFAs can well suppress the gain transients for add/drop operations with various switch speeds, the cumulative transients in cascaded AGC EDFAs give rise to a non-negligible impact. We demonstrate that a high-speed variable optical attenuator (VOA) can suppress such cumulative transients. Error-free operation of a surviving channel under the instantaneous load and unload condition with six cascaded AGC EDFAs is confirmed. The burst mode signal is 7-ms duration with 16-dB range.