Optical Control of Valley Polaritons

Schematic showing control of valley properties in 2-D semiconductors embedded in a microcavity. (Source: Z. Sun)

While the charge and spin proper­ties of electrons are widely utilized in modern day techno­logies such as transistors and memories, another aspect of the sub­atomic particle has long remained un­charted. This is the valley pro­perty which has potential for rea­lizing a new class of technology termed “valley­tronics” – similar to elec­tronics (charge) and spin­tronics (spin). This property arises from the fact that the electrons in the crystal occupy different posi­tions that are quantum mechani­cally distinct.

Now City College of New York physicists led by Vinod Menon have demons­trated how to mani­pulate the valley-property using light by placing two-dimen­sional semi­conductors in a light trapping microcavity. This gave rise to half-light-half matter quasi-particles which have the finger­print of the valley-pro­perty. These quasi-par­ticles were then opti­cally controlled using a laser to access the electrons occu­pying specific valley. The research is a major step towards reali­zation of “valley­tronic” devices for logic gates.

“Observing this property in tradi­tional semi­conductors was not easy. However with the advent of the new class of two-dimen­sional semi­conductors, this property became accessible to mani­pulation,” said Zheng Sun, a graduate student in Menon’s research group. (Source: CCNY)

Reference: Z. Shu et al.: Optical control of room-temperature valley polaritons, Nat. Phot., online 24. July 2017; DOI: 10.1038/nphoton.2017.121

Link: Lab. for Nano and Micro Photonics, Dept. of Physics, City University of New York, New York, USA

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