Franz-Keldysh effect and electric field-induced second harmonic generation in graphene: From one-dimensional nanoribbons to two-dimensional sheet

Abstract

It is well established that external electrostatic fields modify the electronic structure and optical response of materials. Modifications of the optical response of quasi-one-dimensional graphene nanoribbons (GNRs) depend strongly on the direction of the electrostatic field. While transverse fields primarily lift degeneracies in the band structure, longitudinal fields are responsible for considerable nonperturbative Franz-Keldysh effects. Also, electric fields break the inversion symmetry of GNRs and result in strong electric field-induced second harmonic generation. In this work, we study field-induced modifications of the linear and nonlinear optical response of narrow and wide semiconducting armchair GNRs (AGNRs). Both finite and infinite AGNRs with and without electrostatic fields are studied and length convergence is analyzed. Similarly, the width convergence of wide AGNRs to the two-dimensional graphene limit with and without longitudinal fields is investigated.

Study on Electronic and Optical Properties of Graphene Oxide Under an External Electric Field From First-principles

“…The effects of the 𝐸 𝑒𝑥𝑡 adjust the optical response of the 2D graphene. The external dc gates control the Fermi energy and help the photocurrents in graphene material, which are essential for optical modulators and photodetectors, respectively [7]. Therefore, it is very necessary to study the effects of the 𝐸 𝑒𝑥𝑡 , on optical and electronic properties of GO.…”