  The concept of lumped optical nanoelements (or metactronics), wherein
nanometer-scale structures act as nanoinductors, nanocapacitors and
nanoresistors, has attracted a great deal of attention as a simple toolbox for
engineering different nanophotonic devices in analogy with microelectronics.
While recent studies of the topic have been predominantly focused on linear
functionalities, nonlinear dynamics in microelectronic devices plays a crucial
role and provides a majority of functions, employed in modern applications.
Here, we extend the metactronics paradigm and add nonlinear dynamical
modalities to those nanophotonic devices that have never been associated with
optical nanoantennas. Specifically, we show that nonlinear dimer nanoantennae
can operate in the regimes of tristable and astable multivibrators as well as
chaos generators. The physical mechanism behind these modalities relies on the
Kerr-type nonlinearity of nanoparticles in the dimer enhanced by a dipolar
localized surface plasmon resonance. This allows one to provide a positive
nonlinear feedback at moderate optical intensities, leading to the desired
dynamical behavior via tuning the driving field parameters. Our findings shed
light on a novel class of nonlinear nanophotonic devices with a tunable
nonlinear dynamical response.
