All-Optical Control of a Single Plasmonic Nanoantenna–ITO Hybrid

Abstract

We demonstrate experimentally picosecond all-optical control of a single plasmonic nanoantenna embedded in indium tin oxide (ITO). We identify a picosecond response of the antenna-ITO hybrid system, which is distinctly different from transient bleaching observed for gold antennas on a nonconducting SiO 2 substrate. Our experimental results can be explained by the large free-carrier nonlinearity of ITO, which is enhanced by plasmon-induced hot-electron injection from the gold nanoantenna into the conductive oxide. The combination of tuneable antenna-ITO hybrids with nanoscale plasmonic energy transfer mechanisms, as demonstrated here, opens a path for new ultrafast devices to produce nanoplasmonic switching and control.Keywords: active, plasmonic, nanoantenna, hybrid nanostructures, nanophotonics Nanophotonic devices that can efficiently concentrate optical radiation into a nanometer-sized volume are of great interest for many applications in integrated and nonlinear photonics, radiative decay engineering, and quantum information processing. In plasmonics, ultrasmall mode volumes and high local field enhancement are achieved by exploiting the surface plasmon resonances of metal nanostructures. Analogous to radiowave antennas, plasmonic nanoantennas have been developed, providing a high local field enhancement with efficient coupling to far field radiation [1,2]. Active control of the resonance spectrum of a plasmonic nanoantenna is a crucial step toward achieving transistor-type nanodevices for manipulation of the flow and emission of light. Such active nanoplasmonic devices may hold promise for on-chip integration of optical and electronic functionalities [3,4]. A variety of schemes have been proposed and developed to control plasmonic modes using optical, electrical, magnetic, thermal, or mechanical means [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. While propagating surface plasmon polaritons provide a long interaction length, allowing switching at modest intensities [9][10][11][12][13], localized mode switching may benefit from the design of nanoplasmonic modes with strong local field enhancement and high sensitivity to refractive index changes [14][15][16][17][18][19][20]. Large modulation has been obtained recently for plasmonic nanoantennas using an electrically-controlled liquid crystal [18,19]. While liquid crystals provide sizeable tuning of the antenna response, the temporal response is too slow for many applications. Furthermore, a solid-state implementation would be favorable for onchip integration of nanoplasmonic devices.Here, we demonstrate all-optical control of plasmon modes of individual nanoantennas using the nonlinear response of a nanoantenna-ITO hybrid. Transparent conductive oxides have recently been identified as promising materials for plasmonics and transformation optics applications in the near-infrared [21]. Unity-order changes of the refractive index of indium tin oxide (ITO) above its bulk plasmon frequency have been demonstrated using voltage-controlled nanoscale space ...

Interference, Coupling, and Nonlinear Control of High-Order Modes in Single Asymmetric Nanoantennas

“…In symmetric antennas, a redshift of the dipolar resonance was previously found resulting from a reduction in the free carrier density of the ITO substrate. 39 In our case, the response of the asymmetric dimer shows at least three positive and two negative contributions as marked with our earlier findings. 39 The BEM-calculation of the differential extinction cross-section is shown in Fig.…”

“…39 In our case, the response of the asymmetric dimer shows at least three positive and two negative contributions as marked with our earlier findings. 39 The BEM-calculation of the differential extinction cross-section is shown in Fig. 5f) and exhibits the same structure of four contributions to the spectrum for the exact situation where the splitting occurs (L 2 = 420 nm).…”

Spatially, Temporally, and Quantitatively Controlled Delivery of Broad Range of Molecules into Selected Cells through Plasmonic Nanotubes

“…[ 21 ] Among them, it is well known that they are very effective in being injected into a semiconductor material. [22][23][24] In laser nanosurgery, water is usually treated as an amorphous semiconductor [ 25,26 ] in which free-electron density can be generated by exciting electrons from the valence to the conduction band. This process requires activation energy equal to 6.5 eV, whereas the energy necessary to remove an electron from gold in the presence of water is 3.7-2.2 eV, [27][28][29] thus making the plasmonic process strongly favored and effi cient.…”

Ultrafast Nonlinear Control of Progressively Loaded, Single Plasmonic Nanoantennas Fabricated Using Helium Ion Milling

“…Here, we investigate the nonlinear response of the vertically milled antennas induced by picosecond pulsed laser excitation. Picosecond pump−probe experiments were conducted by using the supercontinuum light source as a probe, while the frequency doubled secondary output of the same oscillator was used as a pump to excite the nanoantennas at 530 nm wavelength 22,23 (see Figure 5a). Figure 5a and b shows typical results for antenna J in Figure 2 for the pump−probe change Δσ, normalized to the maximum σ max of the resonance.…”