Researchers from Bengaluru have demonstrated for the first time that the optical properties of metals can be actively controlled using mechanical strain, challenging the long-held belief that these properties remain fixed. The breakthrough could pave the way for programmable nanophotonic devices and advanced optical technologies.
The study, carried out by scientists at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), an autonomous institute under the Department of Science and Technology (DST), focused on ultra-thin films of titanium nitride (TiN), a material widely used in semiconductor-compatible photonic applications.
By applying controlled mechanical strain to TiN films, the researchers observed a significant shift in the material’s plasmon resonance—the way metals interact with light. Advanced microscopy and spectroscopy techniques confirmed that strain directly alters the metal’s electronic behaviour, allowing its optical response to be tuned.
Further theoretical analysis revealed that mechanical strain increases the concentration of free electrons by promoting nitrogen vacancies in the material, resulting in the observed change in optical properties.
Lead researcher Prof. Bivas Saha said the discovery introduces mechanical strain as a powerful new tool for controlling plasmonic behaviour, enabling the development of reconfigurable and programmable optical devices fully compatible with existing CMOS chip technology.
The research was conducted in collaboration with scientists from the University of Sydney, Australia, and is expected to contribute to future advances in on-chip photonics, optical sensing, high-speed communication and next-generation semiconductor technologies.
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