Changing a Material's Properties with Light
Working with what you have can be difficult when what you have does not have the properties you need. When this happens with materials, complicated means may be possible to alter the properties of the material as needed, but not always. Researchers at MIT though have confirmed a theoretical coupling of photons and electrons that should allow a material's properties to be changed, just by shining light on it.
In a crystalline solid, electrons will flow in a periodic pattern matching the pattern of the crystal, which was first theorized by a Swiss physicist named Bloch. Photons, being electromagnetic waves, also have a regular frequency, and their interaction with matter can create Floquet states. What the MIT researchers have observed for the first time are photons and electrons coupling to form Floquet-Bloch states, a combination which is periodic in both space and time. This allows the electronic properties of a material to be affected by the light shined on it.
Though the researchers were working with a topological insulator, this discovery has applications for a great variety of materials, including graphene. Properties such as transparency, conductance, and band-gap width could all be manipulated using properly polarized laser light.