▎ 摘　　要

Graphene doped by lithium atoms supports a strong Dirac plasmon, a weak acoustic plasmon and a strong interband plasmon Li(pi + sigma). Here we demonstrate that applying a positive or negative bias on the lithium-doped graphene causes the appearance ('switching ON') or disappearance ('switching OFF') of the Li(pi + sigma) plasmon and the 'conversion' of the Dirac plasmon into a strong acoustic plasmon. This has two important consequences: 1. bias-controlled UV optical activity of the Li-doped graphene and 2. biascontrolled position of the 2D plasmon centroid. These effects turn out to be very robust and independent of the details of the experimental setup, which means that they should be easily experimentally verified, and very attractive for for potential applications.