Starting with the Lycurgus cup (4th Century) and the fact it appears red when light is shone into it from above and transmitted through the ceramic but appears green when light from outside is reflected off the outside of the cup. We were taken on a brief journey through the developments in stained glass and more detailed analysis of the effects of composition and particle size in the 19th Century.
We were then expertly guided into Plasmonics (Plasmon–ics, ie plasma or a gas of charged particles). At the atomic level metal is nothing more than plasma in a container. Two other concepts were introduced: that of resonance and that of absorptance/reflection. Resonance related to the density of electrons providing potentially tuneable responses, that is, manipulation of the composition of material(s) at the atomic level to obtain the effect(s) required. Reflectance such as that of long wave length radio waves and reflection off the ionosphere (plasma) resulting in radio transmissions travelling around the world.
By the manipulation of nano-particles, much smaller than the wavelengths of light, it is possible to: have glass that reflects all energy in the infra-red spectrum; massively improve the light extraction from LEDs by more effectively guiding light out of the LED’s; creating anti-body coated nano-particles that can attach themselves to cancer cells in the human body and the nano-particles subsequently warmed in response to energy killing the cancer cells; greatly improved computer chips with light as the communication medium.
The future possibilities of nano-technology and Plasmonics are huge. Lighting science and engineering in a way most of us in the conventional lighting industry are not accustomed to.
text : Tim shotbolt