ph8b00325_si_001.pdf (16.42 MB)
Shaping Polaritons to Reshape Selection Rules
journal contribution
posted on 2018-07-10, 00:00 authored by Francisco Machado, Nicholas Rivera, Hrvoje Buljan, Marin Soljačić, Ido KaminerThe discovery of orbital angular
momentum (OAM) in light established
a new degree of freedom by which to control not only its flow but
also its interaction with matter. Here, we show that by shaping extremely
subwavelength polariton modes, for example by imbuing plasmon and
phonon polaritons with OAM, we engineer which transitions are allowed
or forbidden in electronic systems such as atoms, molecules, and artificial
atoms. Crucial to the feasibility of these engineered selection rules
is the access to conventionally forbidden transitions afforded by
subwavelength polaritons. We also find that the position of the absorbing
atom provides a surprisingly rich parameter for controlling which
absorption processes dominate over others. Additional tunability can
be achieved by altering the polaritonic properties of the substrate,
for example by tuning the carrier density in graphene, potentially
enabling electronic control over selection rules. Our findings are
best suited to OAM-carrying polaritonic modes that can be created
in graphene, monolayer conductors, thin metallic films, and thin films
of polar dielectrics such as boron nitride. By building on these findings
we foresee the complete engineering of spectroscopic selection rules
through the many degrees of freedom in the shape of optical fields.