Nanoimprint Lithography (NIL) is a promising technique for fabricating high-throughput, high-performance printable nanodevices. We have demonstrated that NIL is suitable for making large-area nanophotonic structures with high refractive index and good optical transparency.

We developed a specific hybrid organic-inorganic NIL resist for imprinting large-area films in a robust process that allows us to pattern functional films over large areas without the cracks inherent in sol-gel films. Optical titania-based resist films are directly imprinted at low pressure with UV light for two minutes – a process that allows to imprint sub-10 nm titania structures in a new state-of-the-art technique.

The optical properties of the imprinted films are controlled by a post-annealing treatment. We measured a refractive index and optical transparency for the nanostructures as high as 2.1 and 95% respectively in the visible wavelength range. We have already tested simple imprinted structures and have shown that the process is suitable for making photonic devices and creating novel nanophotonic structures.

Our approach could help in the development of novel applications based on photonic nanostructures and open the way to printable photonic devices. We believe that direct imprinting of functional films at the nanometre scale opens up a lot of opportunities and that it could one day it be used to fabricate printable integrated nanophotonic devices.

More information about the technique can be found in the journal Nanotechnology.