Control of valley polarization in gapped graphene by linearly polarized ultrashort optical pulse

Abstract

We present a versatile model of gapped graphene to manipulate valley polarization by using ultrafast linearly polarized pulses of zero areas. First, a circularly polarized pulse of a single oscillation produces a valley-selective population of the conduction band by means of topological resonance. Then we apply a linearly polarized femtosecond-long pulse that changes the valley polarization. The magnitude of such a change depends on the amplitude and the direction of polarization of the pulse. Our protocol provides a favorable platform for applications in valleytronics. • In gapped graphene, valley polarization (VP) can be manipulated by a sequence of ultrafast pulses. • A single oscillation of the chiral pulse generates VP then another oscillation of a linear pulse manipulates it. • The valleys get completely depolarized once a strong ultrafast linearly polarized pulse is introduced. • The proposed effect is the fundamentally fast process and paves a pathway for all-optical ultrafast valleytronics.