Experimental demonstration of dynamic high-speed equalization of three channels using wavelength demultiplexer and acoustooptic modulators

In previous work, we had shown an active equalization of three channels over 2,500 km by using acousto-optic tunable filters (AOTFs). Because the power transients in chains of highly pumped, deeply saturated EDFAs is about several microseconds, the dynamic equalization module should respond faster than it so as to compensate the gain variation. As a result, the AOTF, whose response time is around several μs, is not a satisfactory candidate. The acousto-optic (AO) modulator is a good one because of its submicrosecond rise/fall time and polarization insensitivity. Combined with a silica dense wavelength division multiplexer (DWDM) and dynamic feedback control circuit, we can equalize all channels independently