Nanoplasmonic sensing is a very active and diverse field with a wide variety of applications in chemistry, biomolecular and materials science . Optically resonant molecular systems often display what is called a strong coupling to the nanophotonic systems. This is primarily explored for the nanophotonics active control and in the studies of quantum optics . At the same time, the strong coupling of the molecular resonances to the nanoplasmonic antennas has not been addressed to follow the light-induced molecular processes. Here we combine an exemplary molecular photo-switch, from the spiropyran photochromic family, with anisotropic nanoplasmonic antennas to earn the monitoring tool for the light-activated processes using molecular and nanoplasmonic resonances strong coupling regime. We follow the reversible photo-isomerization of the spiropyran photoswitch from the spiro form to the merocyanine form by tuning in the nanoplasmon antenna to the excitonic state of the merocyanine form (at 570 nm), prompting the formation of a hybrid excitonic-plasmonic state. Our anisotropic nanoantenna provides two polarization-dependent spectrally separated resonances in the visible region, allowing for separate monitoring of the plasmon-exciton strong coupling and the conventional enhanced optical near-field refractive index sensing. This system uncovers a new modality in polaritonic chemistry and optical label-free monitoring of the photo-activated processes and can find applications in photocatalysis, biosensing and in hybrid molecular-nanoantenna actively modulated systems.
 M. I. Stockman, Science 348, 287 (2015); A. Dmitriev (Ed.), Nanoplasmonic Sensors, Springer NY (2012).
 Yoshie, T. et al. Nature 432, 200 (2004) ; Kasprzak, J. et al. Nature Mater. 9, 304 (2010); Reinhard, A. et al. Nature Photon. 6, 93 (2012).
A major challenge facing plasmon nanophotonics is the poor dynamic tunability. A functional nanophotonic element would feature the real-time sizeable tunability of transmission, reflection of light’s intensity or polarization over a broad range of wavelengths, and would be robust and easy to integrate. Here we devise an ultra-thin chiroptical surface, built on 2D nanoantennas, where the chiral light transmission is controlled by the externally applied magnetic field. We produced a class of highly tunable by the magnetic field macroscale bottom-up plasmonic chiroptical surfaces. The tuned parameter is the chiroptical transmission, enabled by the nanoantenna design that accommodates ferromagnetic plasmonic elements. The already significant chiroptical response of this system is further tuned up to 150% by the external magnetic field. The presented compact 2D design promises the easy integration and potentially fast operation in the broad spectral range, enabling this type of functional plasmonic surfaces entering the realm of practical optical devices. The magnetic field-induced modulation of the far-field chiroptical response with this surface exceeds 100% in the visible and near-infrared spectral ranges, opening the route for nanometer-thin magnetoplasmonic light-modulating surfaces tuned in real time and featuring a broad spectral response. For this we design a 2D composite trimer nanoantennas comprising three near-field-coupled nanosized disks of diameters close to 100 nm and identical height of 30 nm, of which one is made of a ferromagnetic material and the other two are made of a noble metal. The use of two materials breaks the 2D rotational symmetry, endowing the handedness to the trimer that results in a chiroptical response in otherwise structurally symmetric nanoantenna. We leverage on the presence of the plasmon resonances in metallic nanoferromagnets to add the magnetoplasmonic functionality to the system.
The realm of nanooptics is usually characterized by the interaction of light with structures having relevant feature sizes
much smaller than the wavelength. To model such problems, a large variety of methods exists. However, most of them
either require a periodic arrangement of a unit cell or can handle only single entities. But there exists a great variety of
functional devices which may have either a spatial extent much larger than the wavelength and which comprise structural
details with sizes in the order of a fraction of the wavelength or they may consist of an amorphous arrangement of
strongly scattering entities. Such structures require large scale simulations where the fine details are retained. In this
contribution we outline our latest research on such devices and detail the computational peculiarities we have to
overcome. Presenting several examples, we show how simulations support the physical understanding of these devices.
Examples are randomly textured surfaces used for solar cells, where guided modes excited in the light absorbing layers
strongly affect the solar cell efficiency, amorphous metamaterials and stochastically arranged nanoantennas. The usage
of computational experiments will be motivated by the unprecedented insight into the functionality of such components.