▎ 摘　　要

The longitudinal current-voltage characteristic of a graphene-based superlattice in high-frequency electric fields, such that the strength of one of the fields oscillates along the superlattice axis and the strength of the other perpendicularly to this axis, is calculated. It is shown that, if there is a transverse high-frequency field only, there exists a possibility for sharply increasing the current density in the negative-differential-conductivity region of the static current-voltage characteristic of the superlattice. The current density exhibits a jump, if the oscillation frequency of the field strength approaches the Bloch oscillation frequency. It is shown that, in such a situation, absorption of an electromagnetic wave in the graphene-based superlattice gives way to amplification.