Efficient plasmonic emission by the quantum Čerenkov effect from hot carriers in graphene

By Ido Kaminer, Y. T. Katan, Hrvoje Buljan, Yichen Shen, O. Ilic, Josué J. López, Liang Jie Wong, John D. Joannopoulos, Marin Soljačić. 2016

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Graphene plasmons have been found to be an exciting plasmonic platform, thanks to their high field confinement and low phase velocity, motivating contemporary research to revisit established concepts in light–matter interaction. In a conceptual breakthrough over 80 years old, Čerenkov showed how charged particles emit shockwaves of light when moving faster than the phase velocity of light in a medium. To modern eyes, the Čerenkov effect offers a direct and ultrafast energy conversion scheme from charge particles to photons. The requirement for relativistic particles, however, makes Čerenkov emission inaccessible to most nanoscale electronic and photonic devices. Here we show that graphene plasmons provide the means to overcome this limitation through their low phase velocity and high field confinement. The interaction between the charge carriers flowing inside graphene and the plasmons enables a highly efficient two-dimensional Čerenkov emission, giving a versatile, tunable and ultrafast conversion mechanism from electrical signal to plasmonic excitation. Graphene plasmons have gained significant interest thanks to their high field confinement and low phase velocity. Here the authors show theoretically that charge carriers propagating in graphene can excite plasmons through a quantum Čerenkov emission process in two dimensions, in the form of plasmonic shock waves.

Subfields: Atomic and Molecular Physics, and Optics, Biomedical Engineering, Civil and Structural Engineering, AI for Physical Sciences