Using tiny arrays of carbon nanotubes, a team of researchers at Rice University has designed nanoscale incandescent light source that could be tuned to precisely emit at specific wavelength, based on the materialsâ configuration.
The so-called nanoscale thermal emitters described in a paper titled âNonâHermitian Selective Thermal Emitters using MetalâSemiconductor Hybrid Resonatorsâ published in the journal of Advanced Materials combine several known phenomena into a unique system that turns heat into light.
According to the research, the system is highly configurable to deliver light with specific properties and at the desired wavelength. The research is a follow up on a recent technique developed by the lab, using carbon nanotubes to channel heat from mid-infrared radiation to improve the efficiency of solar energy systems.
Here, the unique design configuration turns heat into light, and is highly configurable.
âThe previous paper was all about making solar cells more efficient,â explained Gururaj Naik, an assistant professor of electrical and computer engineering at Riceâs Brown School of Engineering. âThis time, the breakthrough is more in the science than the application. Basically, our goal was to build a nanoscale thermal light source with specific properties, like emitting at a certain wavelength, or emitting extremely bright or new thermal light states.
âPreviously, people thought of a light source as just one element and tried to get the best out of it,â he said. âBut we break the source into many tiny elements. We put sub-elements together in such a fashion that they interact with each other. One element may give brightness; the next element could be tuned to provide wavelength specificity. We share the burden among many small partsâ.
âThe idea is to rely upon collective behavior, not just a single element,â Naik said. âBreaking the filament into many pieces gives us more degrees of freedom to design the functionality.â
The system relies on non-Hermitian physics, a quantum mechanical way to describe âopenâ systems that dissipate energyâin this case, heatârather than retain it. In their experiments, Naik and graduate student Chloe Doiron combined two kinds of near-nanoscale passive oscillators that become electromagnetically coupled when heated to about 700ÂșC. When the metallic oscillator emits thermal light, it triggers the coupled silicon disk to store the light and release it in the desired manner.
The light-emitting resonatorâs output can be controlled by damping the lossy resonator or by controlling the level of coupling through a third element between the resonators. âSemiconductors give you a high selectivity but low brightness, while metals give you very bright emission but low selectivity. Just by coupling these elements, we can get the best of both worldsâ, explains Doiron.
Read more: INCANDESCENT LIGHT BULBS AT THE NANOSCALE