Frequency-dependent optical steering from subwavelength plasmonic structures

Abstract

We show theoretically and with numerical simulations that the direction of the in-plane scattering from a subwavelength optical antenna system can be controlled by the frequency of the incident light. This optical steering effect does not rely on propagation phase shifts or diffraction but arises from phase shifts in the localized surface plasmon modes of the antenna. An analytical model is developed to optimize the parameters for the configuration, showing good agreement with a rigorous numerical simulation. The simulation predicts a 25° angular shift in the direction of the light scattered from two gold nanorods for a wavelength change of 12 nm.

From Classical Superposition of Waves to Quantum Interference: Three Level Quantum System for Two Entangled Photons

“…The angular changes in radiations vs the incident wavelength were comparable to those of the gold "T" antenna [17]. But unlike the "T" antenna, far-field radiation patterns of an asymmetric cross showed a 180° rotational symmetry.…”

Plasmonic circuits for manipulating optical information

“…The advantage is the algebra is expressed in terms of the natural quantities associated with LSPs, such as electric permittivity, induced dipole moments, and coupling by electric fields including the polarization properties of the incident light fields. This algebraic approach has been very successful and has enabled us to design quite complex circuits, such as the plasmonic Wheatstone bridge that can be used for phase detection [150,151], all-optical modulation and switching [166], as well as antennas with frequency-dependent beaming [167] and response tailored to the handedness of circular polarization [168].…”

“…Examples of different optical antenna designs are the Yagi-Uda antenna [180,181], cross antennas [182], J-pole [183,184], V antennas [183], and bow-tie antennas [185]. As with radio engineering, it is possible to create antenna arrays [173] for controlling the divergence and radiation direction of a light beam [186,187] and plasmonic structures for steering the radiation direction of light depending on frequency [167] or controlling the propagation direction of plasmons based on phase [188]. The antenna excitation patterns [189,190] can be altered by changing the phase and polarization of the incident light, which affects the plasmon modes that are excited [191].…”

Switchable surface plasmon dichroic splitter modulated by optical polarization

“…Recently, due to the demands on the optical spectrum analyzing beyond the diffraction limit, various types of submicrometer‐sized plasmonic dichroic splitter have been designed by using asymmetric double groove , T‐shaped , and composite cavity structures . By using a cascaded nanocorrugation grating on silver nanowires or nanoantenna system, demonstration of spatial color separation was also reported . Although these studies were quite successful, they have some limitations since the guiding directions of a dichroic splitter are fixed due to their asymmetric geometries and the splitting ratio was not so good.…”