Properties of surface plasmon polaritons on lossy materials: lifetimes, periods and excitation conditions

Abstract

The possibility to excite Surface Plasmon Polaritons (SPPs) at the interface between two media depends on the optical properties of both media and geometrical aspects. Specific conditions allowing the coupling of light with a plasmon-active interface must be satisfied. Plasmonic effects are well described in noble metals where the imaginary part of the dielectric permittivity is often neglected ("perfect medium approximation"). However, some systems exist for which such approximation cannot be applied, hence requiring a refinement of the common SPP theory. In this context, several properties of SPPs such as excitation conditions, period of the electromagnetic field modulation and SPP lifetime then may strongly deviate from that of the perfect medium approximation. In this paper, calculations taking into account the imaginary part of the dielectric permittivities are presented. The model identifies analytical terms which should not be neglected in the mathematical description of SPPs on lossy materials. These calculations are applied to numerous material combinations resulting in a prediction of the corresponding SPP features. A list of plasmon-active interfaces is provided along with a quantification of the above mentioned SPP properties in the regime where the perfect medium approximation is not applicable.

Ultraslow long-living plasmons with electromagnetically induced transparency

“…The results are extrapolated to the regime of smaller group velocities achieved for atomic densities typically used in EIT experiments. The obtained correlation between SPP lifetime and group velocity agrees with the findings of Derrien et al [28], where moderate lifetime enhancement has been discussed at various metal-air interfaces. It should be stressed that the increased lifetime is crucial for the effective slowdown of SPPs; the slowdown by two orders of magnitude results in τ ≈ 1 ns and corresponding reduced plasmon spectral width Γ ≈ 1 GHz, which is sufficiently narrow to fit inside the transparency window.…”

Maxwell Meets Marangoni—A Review of Theories on Laser‐Induced Periodic Surface Structures

“…For the excitation of SPPs, specific conditions on the dielectric permittivity of the two involved media have to be fulfilled. [32] For common metals (m) in contact with a dielectric (d, air or vacuum) exposed to laser wavelengths in the visible to IR spectral region, the condition for "SPP activity" can be simplified as Re( m ) < −1. [31,32] Particularly for irradiation with ultrashort laser pulses, this excitation channel is of major importance and may be enabled even for semiconductors and dielectrics as the initially plasmonically nonactive materials can transiently be turned into a metallic (SPP active) state, once a critical density of electrons in the conduction band is exceeded.…”

“…[32] For common metals (m) in contact with a dielectric (d, air or vacuum) exposed to laser wavelengths in the visible to IR spectral region, the condition for "SPP activity" can be simplified as Re( m ) < −1. [31,32] Particularly for irradiation with ultrashort laser pulses, this excitation channel is of major importance and may be enabled even for semiconductors and dielectrics as the initially plasmonically nonactive materials can transiently be turned into a metallic (SPP active) state, once a critical density of electrons in the conduction band is exceeded. [33,34] An important remark must be made regarding the excitability of SPPs on flat surfaces that points back to the momentum conservation law: for a given laser frequency, a photon propagating in free-space has a smaller momentum than an SPP as the two have different dispersion relations that do not cross.…”

Optimization of femtosecond laser processing in liquids

“…Liquid environment is also used in the LIPSS (laser-induced periodic surface structures) formation experiments [11][12][13][14]. In the frames of plasmonic model of the LIPSS formation, the refractive index of the liquid environment should control the pattern period [15], thus experiments in different liquids could be used for an experimental test of this theory. However the broadening of the spectrum of the incident light in the liquid makes the results difficult for interpretation especially due to the fact that the white light generated in a nonlinear medium can also make the LIPSS [16].…”