  Based on calculations of the electronic structure of coupled multiple quantum
dots, we study systemically the transport properties of the system driven by an
ac electric field. We find qualitative difference between transport properties
of double coupled quantum dots (DQDs) and triple quantum dots. For both
symmetrical and asymmetrical configurations of coupled DQDs, the field can
induce the photon-assisted Fano resonances in current-AC frequency curve in
parallel DQDs, and a symmetric resonance in serial DQDs. For serially coupled
triple quantum dots(STQDs), it is found that the $\Lambda$-type energy level
has remarkable impact on the transport properties. For an asymmetric (between
left and right dots) configuration, there is a symmetric peak due to resonant
photon induced mixing between left/right dot and middle dot. In the symmetric
configuration, a Fano asymmetric line shape appears with the help of ``trapping
dark state". Here the interesting coherent trapping phenomena, which usual
appear in quantum optics, play an essential role in quantum electronic
transport. We provide a clear physics picture for the Fano resonance and
convenient ways to tune the Fano effects.
