Scientists have found new things about ghost polaritons – a brand new form of surface waves, which carry nanoscale light, that’s tided with material oscillations. It has highly collimated propagation properties.
Scientists have observed this phenomenon in a common material, in calcite. This phenomenon shows how ghost polaritons can help the control of infrared nano-light for energy harvesting, sensing, and signal processing.
Nanophotonics at infrared and terahertz frequencies are very important for sensitive and ultracompact, low-loss technologies for chemical and bio-molecular diagnosis, and plenty of other applications. They can also make it easier for enhanced light-matter interactions – it has actually become essential for technologies.
Scientists from the City University of New York Advanced Science Research Center have shown that calcite, which is a well-known bulk crystal, is used quite commonly in many other technologies, and it can naturally support ghost polaritons.
The light interactions that take place with calcite resulted in unexpected infrared phonon polariton responses. They have found out that the calcite, which is very easy to polish, can support ghost polariton surface waves that have complex momentum – something way different than what we’ve seen so far.
“Polaritonics is the science and technology of exploiting strong interactions of light with matter, and it has revolutionized optical sciences in the past few years. Our discovery is the latest example of the exciting science and surprising physics that can emerge from exploring polaritons in conventional materials like calcite,” stated Andrea Alù, Einstein Professor of Physics. They used s-SNOM in order to test these ghost polaritons, and they have shown the nano-light propagation for 20 micrometers, which is a record.
“We have been thrilled to find a new solution of Maxwell’s equations featuring complex, out-of-plane momentum. And even more excitingly, we have been able to observe it in a very common crystal,” said Guangwei Hu, co-first author.