The application of an external time dependent potential to a superlatt
ice modifies its transport properties. We have analyzed theoretically
the photoassisted tunneling current through a superlattice in the pres
ence of an a.c. potential applied at both sides of the superlattice. I
n the presence of a finite d.c. bias, the miniband structure for the c
onduction band of the superlattice becomes the well known Stark ladder
and the tunneling current takes place sequentially. The a.c, field in
duces absorption and emission processes which are reflected as new fea
tures in the current density. These new features in the tunneling curr
ent are due to new effective tunneling channels coming from the photos
ide bands which are opened, and which produce additional current steps
in the characteristic curve. Our theoretical results are in good agre
ement with the available experimental evidence.