  The study of hybrid modes in a single dimer of neighboring antennas is an
essential step to optimize the far-field electromagnetic (EM) response of
large-scale metasurfaces or any complex antenna structure made up of
subwavelength building blocks. Here we present far-field infrared spatial
modulation spectroscopy (IR-SMS) measurements of a single thermally excited
asymmetric dimer of square metal-insulator-metal (MIM) antennas separated by a
nanometric gap. Through thermal fluctuations, all the EM modes of the antennas
are excited and hybrid bonding and antibonding modes can be observed
simultaneously. We study the latter within a plasmon hybridization model, and
analyse their effect on the far-field response.
