Polaritonic quantization in nonlocal polar materials

Abstract

In the Reststrahlen region, between the transverse and longitudinal phonon frequencies, polar dielectric materials respond metallically to light and the resulting strong light-matter interactions can lead to the formation of hybrid quasiparticles termed surface phonon polaritons. Recent works have demonstrated that when an optical system contains nanoscale polar elements these excitations can acquire a longitudinal field component as a result of the material dispersion of the lattice, leading to the formation of secondary quasiparticles termed longitudinal-transverse polaritons. In this work we build on previous macroscopic electromagnetic theories developing a full second-quantised theory of longitudinal-transverse polaritons. Beginning from the Hamiltonian of the light-matter system we treat distortion to the lattice introducing an elastic free energy. We then diagonalise the Hamiltonian, demonstrating the equations of motion for the polariton are equivalent to the those of macroscopic electromagnetism and quantise the nonlocal operators. Finally we demonstrate how to reconstruct the electromagnetic fields in terms of the polariton states and explore polariton induced enhancements of the Purcell factor. These results demonstrate how nonlocality can narrow, enhance and spectrally tune near field emission with applications in mid-infrared sensing.

Weyl semimetal mediated epsilon-near-zero hybrid polaritons and the induced nonreciprocal radiation

“…AlN is a uniaxial anisotropic material that can support the propagation of SPhPs, the principle dielectric permittivities differ and each of them can be defined by eqn (1) with a unique set of material parameters. AlN is an uniaxial crystal that features one extraordinary crystal axis (>) along which the dielectric permittivity is different from that along the two ordinary axes (8). Details of the used material parameters are summarized in Table 1.…”

“…[1][2][3][4][5] Compared to bulk crystals, the identified surface phonon polaritons (SPhPs) have recently attracted great interest due to their unique properties, which originate from the coupling of free-photons to optical phonons. [6][7][8][9][10] Recent achievements in the domain of nanophotonics have shown that SPhPs are promising constituents for MIR technology, owing to the possibility to solve the intrinsic loss challenge of plasmonics and offering great potential for technological aspects, such as all-optical switching, highly efficient sensing, or enhanced nonlinear-optical conversion efficiency. [11][12][13][14] SPhPs are excitations that emerge from light-matter interaction with phonons in the strong coupling limit, yielding hybrid modes with both phononic and EM characteristics.…”

Dual-wavelength switchable perfect infrared absorber based on multiple ENZ materials

“…Improving the ability to engineer light-matter interactions in the infrared region is commanding considerable attention from the nanophotonics, plasmonics, and physics communities 1 – 5 The optical devices applied in the infrared region, such as absorbers, converters, modulators, and sensors, have developed rapidly 6 – 11 In the past few years, researchers have devoted themselves to ameliorate the working performance of infrared absorbers to meet the actual demand, which includes high absorptance, broad bandwidth, and wide absorption angle 12 …”