Nature Commun. 3, 906 (2012)

Graphene possesses extraordinary electrical properties that could potentially be used in the development of high-speed optoelectronic devices, such as photodetectors, optical modulators and solid-state lasers. Unfortunately, its single-atom thickness restricts its ability to absorb or emit light, limiting the performance of such devices. Hence, to enhance the interaction between graphene and light, Michael Engel and colleagues have tried embedding a graphene transistor into a planar optical cavity.

When an emitter — such as an atom, molecule or quantum dot — is placed inside a cavity whose resonance is matched to one of its radiative transitions, the emission and absorption rate of the transition is enhanced. By the same token, Engel et al. find that the optical absorption and generated photocurrent of their transistor is greatest when illuminated with light at the resonant frequency of the cavity. Moreover, when the transistor–cavity devices are heated by passing a current through them, their infrared emission shows a sharply peaked (as opposed to black-body) distribution.