Coherent control of harmonic generation in semiconductor superlattices: single-mode response

We study the harmonic generation spectrum in a semiconductor superlattice (a quantum-dot array) at slow relaxation. The effect of single-mode response in a meander electric field is demonstrated: for certain values of field parameters the extremely wide discrete output spectrum with slowly decaying tails (multi-harmonic generation) shrinks to one single harmonic (single-harmonic generation). Similarly, the effect is manifested in the continuous transition spectrum by diminishing the divergencies (peaks) at all odd harmonics, but one. This effect has no analogs in smooth harmonic fields. Substantial control over the spectrum is demonstrated.