Researchers from the Indian Institute of Technology (IIT) Guwahati and Columbia University in the USA have pioneered a novel nanopatterning technique using a straightforward tabletop infrared (IR) laser. This breakthrough, led by Dr. Rishi Maiti, an Assistant Professor in the Department of Physics at IIT Guwahati and former post-doctoral scientist from Alexander Gaeta’s quantum and non-linear photonics group, has been detailed in the prestigious journal, Science Advances.

Nanopatterning, the process of creating ultra-fine patterns on materials at the nanometer scale—one hundred thousand times smaller than a human hair—is essential for developing advanced optical devices such as light detectors, solar cells, lasers, and LEDs. Traditional nanopatterning methods are often complex and expensive, necessitating specialized equipment like clean rooms and electron beam lithography machines, or involving high local heating and plasma.

In search of a more accessible and cost-effective alternative, the team employed a method called “optical driving,” which utilizes the resonance frequency principle in materials. Their innovative “unzipping” technique, executed with an IR laser, allowed them to cleave hexagonal boron nitride and produce atomically sharp lines only a few nanometers wide. Using a laser wavelength of 7.3 micrometers, they achieved precise and clean lattice breaks, enabling the creation of controllable nanostructures.

Furthering their research, the scientists “unzipped” two parallel lines to form a nano-dimensional cavity capable of trapping phonon-polaritons—unique quasi-particles resulting from the interaction of light and vibrations. These particles can focus light into extremely small spots, which is advantageous for highly sensitive mid-infrared sensing and spectroscopy.

Dr. Rishi Maiti highlighted the significance of this development, stating, “This novel nano-patterning technique using optically induced strain opens doors to a myriad of possibilities in nanoscience and technology. Its simplicity and effectiveness mark a significant advancement in the field, with far-reaching implications across various industries.”

Dr. Maiti envisions the breakthrough having diverse applications, including the creation of hard masks for electrode fabrication on 2D materials and the formation of twisted heterostructures for quantum technologies.