Researchers at the University of Ottawa have made a groundbreaking discovery that challenges our understanding of light-material interactions. They found that engineered achiral (symmetric) materials, called achiral plasmonic metasurfaces, can selectively absorb light based on the handedness of the wavefront. This surprising finding contradicts the long-held belief that such materials are indifferent to optical probes. The research, led by Professor Ravi Bhardwaj and Ph.D. student Ashish Jain, promises significant advancements in optical devices, such as sensors and switches, as well as new possibilities for advanced sensing and measurement technologies.
Unravelling the Mystery of Achiral Materials
For 100 years, scientists had thought that achiral (non-chiral or symmetric) materials were blind to light’s polarization. Now, researchers at the University of Ottawa have blown this assumption out of the water.
Their research, which has been published in the journal ACS Nano, shows that these materials can demonstrate an extremely sharp absorption for light with specific handedness of wavefront. The discovery offers possibilities for the design and application of optical elements because it demonstrates that unique light absorption properties can take place even in symmetrical materials.
The Science of the Breakthrough
The team of researchers lead by Prof. Ravi Bhardwaj and Ph.D. Student Ashish Jain, used a similar light apparatus created by Prof Ebrahim Karimi’s Structural Quantum Optics (SQO) group to check the capacity of achiral plasmonic metasurfaces to absorb light.
These detections were discovered by their experiments on the selective absorption of light is a consequence of compositions and degrees in which different fractions of light are more or less engaged with material. This surprising consequence runs counter to the dogma that such materials are optically probe-insensitive.
For decades, we thought these materials couldn’t distinguish in how they absorb polarized light,” says Prof. Bhardwaj. However, our research reveals that we can control and tune this absorption to as high as 50% through the use of a unique twisted light manifesting topological charge. These findings potentially change the landscape for advanced optics and sensing technologies.
New Potentials in Optics
If the research proves successful, these findings could lead to major advances in optical devices like sensors and switches. By demonstrating that symmetric materials can be selective absorbers of light, the discovery has widened the prospects of realizing novel plasmonic-based spectroscopy and sensing technologies in the future.
Professor Bhardwaj adds, ” Our research not only shatters the myth of its non-existence in achiral structures but also paves the way for superior next-generation plasmonic-based spectroscopy and sensing through boosted optical metrology.”
Ashish Jain, lead author of the paper, said: “One of the beauties of our findings is that both topology and symmetry can coexist for a given photonic frequency. Such a case has not been predicted or observed before in topological photonics literature. “Topologies have been discussed… but how one can invoke high-symmetry properties in such systems — this aspect has not been pursued to date. What this breakthrough could mean outside of laboratories is that it opens the door to creating a new generation of optical devices, which can change everything from healthcare to telecommunications.
