Surface Polariton‐Like s‐Polarized Waveguide Modes in Switchable Dielectric Thin Films on Polar Crystals

Abstract

Surface phonon polaritons (SPhPs) and surface plasmon polaritons (SPPs), evanescent modes supported by media with negative permittivity, are a fundamental building block of nanophotonics. These modes are unmatched in terms of field enhancement and spatial confinement, and dynamical all‐optical control can be achieved, e.g., by employing phase‐change materials. However, the excitation of surface polaritons in planar structures is intrinsically limited to p‐polarization. On the contrary, waveguide modes in high‐permittivity films can couple to both p‐ and s‐polarized light, and in thin films, their confinement can become comparable to surface polaritons. Here, it is demonstrated that the s‐polarized waveguide mode in a thin Ge3Sb2Te6 (GST) film features a similar dispersion, confinement, and electric field enhancement as the SPhP mode of the silicon carbide (SiC) substrate, while even expanding the allowed frequency range. Moreover, it is experimentally shown that switching the GST film grants nonvolatile control over the SPhP and the waveguide mode dispersions. An analytical model is provided for the description of the GST/SiC waveguide mode and it is shown that the concept is applicable to the broad variety of polar crystals throughout the infrared spectral range. As such, complementarily to the polarization‐limited surface polaritons, the s‐polarized waveguide mode constitutes a promising additional building block for nanophotonic applications.

In3SbTe2 as a programmable nanophotonics material platform for the infrared

“…In contrast, phase-change materials (PCMs) offer non-volatile tuning. Because of the huge property contrast between their amorphous and crystalline phases resulting from a unique bonding mechanism [18][19][20][21] , they enable exciting tuneable functionalities like waveguiding [22][23][24] , chemical sensing 25 , light detection 26 , and emission 27 , as well as lensing 28 . This makes them prime candidates for non-volatile nanophotonic applications such as integrated optical memories, color displays, or active metasurfaces 1,29 .…”

Combining Switchable Phase‐Change Materials and Phase‐Transition Materials for Thermally Regulated Smart Mid‐Infrared Modulators

“…The presented concepts of combining PTMs and PCMs, that is, volatile and non-volatile switching mechanics, within the same device are not limited to the shown smart modulators and could, for example, be extended to polariton nanophotonics. [51][52][53][54] Exploiting both the advantages of static function tuning and dynamic modulation, they promise fundamentally increased tuning capabilities of nanophotonic components.…”

Nonlocal scattering matrix description of anisotropic polar heterostructures

“…These modes allow for deep sub-wavelength control of light by hybridising it with the optic phonon modes of a polar lattice [2]. The resulting modes are morphology dependant, making them highly tuneable [3][4][5][6][7][8] with potential applications in nonlinear optics [9][10][11], design of infrared thermal emitters [12][13][14] and design of nanophotonic circuitry [15][16][17][18]. As polar nanophotonics matures, greater interest is being placed on the use of of multi-material systems, exploiting the mature technologies available for fabrication of semiconductor heterostructures.…”