Reflection of Cylindrical Surface Waves

Abstract

The reflection of the radially polarized surface wave on a metal wire at an abrupt end is derived. This theory allows for straightforward calculation of the reflection coefficient, including the phase and the amplitude, which will prove useful to the many applications in nanoplasmonics and terahertz spectroscopy. The theory shows excellent quantitative agreement with past comprehensive numerical simulations for small wires and for predicting the minima in reflection for larger wires. Using this theory, the wavelength dependent reflection is calculated for gold rods of diameter 10 nm, 26 nm and 85 nm, from which the Fabry-Perot resonance wavelengths are found. The Fabry-Perot resonances show good agreement with experimentally measured surface plasmon resonances in nanorods. This demonstrates the predictive ability of the theory for applications involving widely-used nanorods, optical antennas and plasmonic resonators.

Light scattering under nanofocusing: Towards coherent nanoscopies

“…For the same purpose, the nanocone base diameter needs to be accordingly chosen [34]. When E inc reaches the tip, the nanocone radius is so small that most of P inc is reflected backwards [49] and it propagates towards the base, where it is radiated into the far field. Moreover, if a scatterer is placed near the tip, E sca couples to the nanocone and reaches the lens in the same spatial mode of the back-reflected E inc .…”

Circular optical nanoantennas: an analytical theory

“…By accounting for that additional phase, the length of the nanoantenna as perceived optically differs from its geometrical length. This phenomenon is sometimes termed the apparent length change of the nanoantenna which turned out to be essential since it strongly affects the resonance positions [31][32][33][34][35][36][37] . In the past this additional phase contribution has been considered either ad hoc without further justification or as a free parameter in an adapted model.…”

“…Such tedious procedures were necessary since the analytical calculation of the complex reflection coefficient turned out to be fairly involved. To date such results are only available for a few simplified geometries 36,38 . Understanding and predicting the com-…”

Comprehensive Surface-Wave Description for the Nano-scale Energy Concentration with Resonant Dipole Antennas

“…1d), ρ and τ are the reflection and transmission coefficients of the SPP at the nano-gap (Fig. 1e), and r is the reflection coefficient of the SPP at the antenna termination [32,35] (Fig. 1f).…”

“…Since very little energy is lost at the nano-gap for an incident SPP, |ρ+τ| is only slightly smaller than 1 (|ρ+τ|=0.91 at λ=1 μm) (see a demonstration in reference [39]). On the other hand, |r| is close to 1 due to the strong reflection of the SPP at the antenna termination [35] (|r|= 0.88 at λ=1 μm). In addition, |u|=exp[−k 0 Im(n eff )L]≈1 due to the weak damping of the propagative SPP along the antenna arm (n eff =1.48+0.035i at λ=1 μm).…”