Hyperbolic Phonon Polaritons in Suspended Hexagonal Boron Nitride

Highly confined and low-loss hyperbolic phonon polaritons in hexagonal boron nitride possess properties analogous to surface plasmon polaritons, but with enhanced confinement and lower loss. Their properties have been so far mostly studied on dielectric substrates, which provide an asymmetric environment for polariton propagation, and add to damping. In this work, we investigate hyperbolic phonon polaritons over suspended hexagonal boron...