Synopsis: A Polariton Fridge for Semiconductors

A gas of polaritons can serve as a coolant fluid that transports heat away from a semiconductor microcavity.
Synopsis figure
Yoan Léger/Institut national des sciences appliquées de Rennes

In laser cooling schemes, photons take energy and momentum from atoms and molecules, bringing them to near-zero temperatures. Similar methods could cool semiconductor devices without the need for noisy cryostats or cryogenic liquids. But cooling a solid using lasers remains challenging: light absorbed by the material is rapidly converted into lattice vibrations (phonons), heating up the solid. Now, Maxime Richard at the Institut Néel of the University of Grenoble and CNRS, France, and colleagues have demonstrated a new cooling technique that uses a gas of so-called “exciton polaritons” to cool a semiconductor material.

In a semiconductor, exciton polaritons are hybrid states formed through the coupling of photons with excitons (bound electron-hole pairs). Being partly photons and partly excitons, they can interact with both light and phonons, allowing efficient energy exchange between the two. In the authors’ scheme, blue laser light generates “cold” polaritons in a 10-micrometer-sized spot within a semiconductor cavity designed to optimize the polariton-phonon coupling. Each generated polariton can then absorb a phonon, generating a higher-energy “hot” polariton. Finally, the hot polariton recombines radiatively, emitting a photon that leaves the cavity. The net effect is a cooling of the cavity through the loss of vibrational energy.

Since the cavity is only excited locally by the laser and is not thermally isolated, the authors could not measure a macroscopic temperature drop for the whole system. But by probing the crystal’s vibrations, they could determine the cooling power generated by their scheme. The results suggest that such a “polariton fridge” could efficiently cool nanoscale semiconductor devices.

This research is published in Physical Review Letters.

–Matteo Rini


More Features »


More Announcements »

Subject Areas

OpticsMaterials Science

Previous Synopsis

Fluid Dynamics

Coiling Viscous Jets

Read More »

Next Synopsis

Related Articles

Focus: Ultrafast Switch with Organic Crystal
Condensed Matter Physics

Focus: Ultrafast Switch with Organic Crystal

An organic crystal was switched between paraelectric and ferroelectric states in a picosecond. Similar materials could eventually serve as extremely fast digital switches. Read More »

Synopsis: A Neat Way to Slow Down Light

Synopsis: A Neat Way to Slow Down Light

A new technique slows down light in a crystal by simply shining a laser on it and varying an applied voltage. Read More »

Focus: Reversing Light Scattering with a Handful of Photons

Focus: Reversing Light Scattering with a Handful of Photons

When a beam of light is sent through a nearly opaque material, the scattered light that emerges can be unscrambled even with relatively few photons detected. Read More »

More Articles