Until recently, the production of planar arrays of hybrid nanoantennas for light manipulation was considered an extremely painstaking process. The research group has developed a technique for creating such arrays of hybrid nanoantennas and for high-accuracy adjustment of individual nanoantennas within the array. This was made possible by combining two production stages: lithography and precise exposure of the nanoantenna to a femtosecond laser.
The practical application of hybrid nanoantennas lies, in particular, within the field of ultradense data recording. Modern optical drives can record information with density around 10Gbit/inch2. Although such dimensions are comparable to the size of the nanoantennas, the scientists propose to additionally control their colour in the visible spectrum. This procedure leads to the addition of another 'dimension' for data recording, which increases the data storage capacity of the system.
The nanoantennas are made up of a truncated silicon cone with a thin golden disk located on top. The researchers demonstrated that, thanks to nanoscale laser reshaping, it is possible to precisely modify the shape of the golden particle without affecting the silicon cone. The change in the shape of the golden particle results in changing optical properties of the nanoantenna as a whole due to different degrees of resonance overlap between the silicon and golden nanoparticles.
"Our method opens a possibility to gradually switch the optical properties of nanoantennas by means of selective laser melting of the golden particles. Depending on the intensity of the laser beam the golden particle will remain disc-shaped, convert into a cup or become a globe. Such precise manipulation allows us to obtain a functional hybrid nanostructure with desired properties in the flicker of a second," explained Sergey Makarov, researcher at the Department of Nanophotonics and Metamaterials of ITMO University.
Apart from ultradense data recording, the selective modification of hybrid nanoantennas can help create new designs of hybrid metasurfaces, waveguides and compact sensors for environmental monitoring. In future, the research group plans to focus on the development of such specific applications of their hybrid nanoantennas.
