"We are the first to show a picture of these quasiparticles and how they propagate, interfere and emit," said assistant professor Zhe Fei.
In this study, exciton-polaritons were observed by shining a laser on the sharp tip of a nano-imaging system aimed at a flake of molybdenum diselenide (MoSe2) – a layered semiconductor that supports excitons.
According to the team, past research projects have used spectroscopes to record exciton-polaritons as resonance peaks or dips in optical spectra. Until recent years, most studies have only observed the quasiparticles at cold temperatures of -230°C.
The Iowa group, however, worked at room temperature with a scanning near-field optical microscope to take nano-optical images of the quasiparticles. They measured a propagation length of more than 12µm.
By changing the thickness of the MoSe2 semiconductor, the team showed they could manipulate the properties of the exciton-polaritons.
The researchers believe their work could have a significant role in developing future applications for quasiparticles. One day they could be used to build polariton transistors and nanophotonic circuits to replace electronic circuits for nanoscale energy or information transfer.
“Nanophotonic circuits with their large bandwidth could be up to 1million times faster than current electrical circuits,” Fei concluded.
