A Single-Crystalline Silver Plasmonic Circuit for Visible Quantum Emitters

Abstract

x5 x0.5 remote excitation emission remote detection nano-bead far-field fluorescence image two-wire transmission line 1μmPlasmonic waveguides are key elements in nanophotonic devices serving as optical interconnects between nanoscale light sources and detectors. Multimode operation in plasmonic two-wire transmission lines promises important degrees of freedom for near-field manipulation and information encoding. However, highly confined plasmon propagation in gold nanostructures is typically limited to the near-infrared region due to ohmic losses, excluding all visible quantum emitters from plasmonic circuitry. Here, we report on top-down fabrication of complex plasmonic nanostructures in single-crystalline silver plates. We demonstrate controlled remote excitation of a small ensemble of fluorophores by a set of waveguide modes and emission of the visible luminescence into the waveguide with high efficiency. This approach opens up the study of nanoscale lightmatter interaction between complex plasmonic waveguides and a large variety of quantum emitters available in the visible spectral range.Propagating surface plasmon polaritons can break the diffraction limit 1 and find applications in optical communication, sensing and quantum information 2,3 . Whereas single nanowires of noble metals are extensively studied as plasmonic waveguides 4,5 , recent research focuses on multimode operation in more complex geometries like two-wire transmission lines. These waveguides offer two fundamental modes which can be selectively excited with an optical antenna and detected by means of a mode detector 6 . Such waveguides find application in polarization manipulation 7 , local mode-conversion 8 , coherent control 9 and spin-dependent flow 10 . In the last years such complex plasmonic and high-quality nanostructures have been mainly fabricated by focused ion beam milling of single-crystalline gold plates 11-14 .Long-range plasmonic waveguiding in gold structures is however limited to the near-infrared spectral range due to ohmic losses in the visible range 15 . This drastically restricts the choice of emitters available for quantum plasmonic experiments [16][17][18] . In contrast to gold, silver leads to reduced losses in the visible spectral range 19-21 although care has to be taken to avoid surface degradation 22 . Chemically grown silver nanowires have been successfully coupled with visible quantum emitters 4,23,24 . More complex shapes need to be manufactured by focused ion beam milling of single-crystalline silver films or flakes 25,26 .Let us start by demonstrating the advantages of silver plasmonics with the example of a two-wire transmission line, formed by two parallel nanowires separated by a gap of a few tens of nanometers ( Fig. 1). We label the two fundamental eigen-modes by the symmetry of their a) Electronic mail: markus.lippitz@uni-bayreuth.de 550 650 750 600 700 wavelength λ (nm) propagation length (µm) 0 2 4 6 8 Ag as Ag s Ag ho guided leaky mode as mode ho E x (arb.u.) max min 0 mode s + -+ + -glass air Al 2 O ...

Spin–Orbit Controlled Excitation of Quantum Emitters in Hybrid Plasmonic Nanocircuits

“…Yinhui Kan [12][13][14] ), focused ion-beam milling (for V-shaped channels [15,16] ) and other sophisticated fabrication/assembly techniques. [17][18][19] Dielectric loaded surface plasmon polariton waveguides (DLSPPWs) can be considered as a promising integration platform to overcome this issue, because the topdown lithography-based fabrication techniques make it easier to embed preselected QEs inside the dielectric waveguides.…”

“…[ 1–8 ] Different kinds of plasmonic waveguides, including metal wedges, V‐grooves, single and parallel nanowires, have been considered for QE coupling to strongly confined plasmon modes in the form of propagating surface plasmon polaritons (SPPs). [ 9–18 ] Even though these waveguides are able of supporting extremely strongly confined SPP modes, their suitability for deterministic, accurate and practical integration with QEs is rather challenging, if possible at all, due to their complicated fabrication involving chemical synthesis (for metallic nanowires [ 12–14 ] ), focused ion‐beam milling (for V‐shaped channels [ 15,16 ] ) and other sophisticated fabrication/assembly techniques. [ 17–19 ] Dielectric loaded surface plasmon polariton waveguides (DLSPPWs) can be considered as a promising integration platform to overcome this issue, because the top–down lithography‐based fabrication techniques make it easier to embed preselected QEs inside the dielectric waveguides.…”

Single Photon Emitters Coupled to Plasmonic Waveguides: A Review

“…In this direction, gapplasmon waveguides have been fabricated using focussed ion beam milling of mono-crystalline silver flakes and coupled to quantum emitters. [68][69][70][71][72]…”

Integration of Single-Photon Emitters in 2D Materials with Plasmonic Waveguides at Room Temperature

“…Efficient coupling of a single-photon emitter with an optical waveguide is essential for implementing a quantum photonic integrated circuit [1]. In particular, when the single-photon emitter is coupled to a plasmonic waveguide, the local density of states (LDOS) of the emitter is increased, and the photon emission is enhanced [2][3][4][5][6][7][8]. This feature was observed by integrating single-photon emitters with randomly dispersed metal nanowires on a substrate [9][10][11][12].…”