Abstract

Optical phonons at the surface of a nanostructured polar crystals can hybridize with light, creating mixed excitations called localized phonon polaritons. Those interface-bound excitations are in many regards mid-infrared analogous of localized plasmons supported by metallic resonators, but they absent themselves from the Ohmic loss characteristic of plasmonic systems. Localized phonon polaritons are developing into an innovative platform for mid-infrared quantum polaritonics. This is due to their extremely small mode volumes, long lifetimes, and large nonlinearities, as well as the relative facility to fabricate nanoresonators with features at the 100nm scale. In this talk I will give an overview of our investigations into this innovative platform. I will start by reviewing localized phonon polaritons main features [1] and introducing a microscopic quantum theory capable of capturing their peculiar properties [2]. I will then present some recent advances we obtained in this field: from the observation of strong coupling between localized and propagative modes [3], to nonlinear polariton scattering [4,5].

[1] C. R. Gubbin, S. A. Maier, and S. De Liberato, PRB 95 , 035313 (2017) [2] C. R. Gubbin, S. A. Maier, and S. De Liberato, PRB 94 , 205301 (2016) [3] C. R. Gubbin, et al., PRL 116 , 246402 (2016) [4] I. Razdolski, et al., Nano Lett. 16, 69546959 (2016) [5] C. R. Gubbin and S. De Liberato, arXiv:1701.06729