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Graphene nanophotonics make their way to practical use

EU-funded scientists have demonstrated applications of graphene as an alternative material for nanophotonics, with potential impact across a wide range of photonics devices.
Graphene nanophotonics make their way to practical use
Graphene, a genuinely 2D material composed of a single layer of carbon atoms, has attracted great interest since its experimental isolation because of its extraordinary electronic, mechanical and optical properties. The unique properties of graphene have a strong effect on guided electromagnetic surface waves, called surface plasmons.

It is expected that surface plasmons and the associated optical fields can be tuned electrically by varying the graphene carrier density. Experimental work within GRANOP (Graphene nano-photonics) indicated that graphene plasmons can be confined to volumes millions of times smaller than propagating plasmons in free space.

In addition, scientists showed that, under realistic conditions, the highly confined optical fields of plasmons give rise to interactions over picosecond timescales – significantly shorter than the anticipated plasmon lifetime. The GRANOP team took advantage of this interaction and the intrinsic non-linearity of graphene to realise a single-photon switch.

Specifically, the optical field confinement was used to turn a graphene nanostructure into a tunable resonant cavity with extremely small mode volume. The cavity resonance was controlled in situ by gating the graphene. The possibility to switch on and off plasmon modes is expected to pave the way towards graphene-based optical transistors.

The combination of nanoelectronics and nano-optics enables the development of a plethora of nano-optoelectronic devices. Among others, strongly enhanced light-matter interactions are foreseen for quantum devices. Before the close of the project, scientists demonstrated strong interactions between graphene and erbium ions as nanoscale light emitters.

By placing the erbium ions at a few nanometres distance from graphene, they were able to modify the relaxation rate of excited erbium ions, which emit light at the technologically relevant telecommunication wavelength of 1.5 µm. Moreover, they could control whether the emitter decays into electron-hole pairs, emitted photons or graphene plasmons.

GRANOP work on controlling the relaxation rates and pathways of such light emitters will have applications in fields ranging from quantum information processing and light collection to sensing (bio)molecules.

Related information


Graphene, nanophotonics, surface plasmons, optical fields, GRANOP, light emitters
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