Gold, Copper, Silver and Aluminum Nanoantennas to Enhance Spontaneous Emission

Mohammadi, Ahmad; Sandoghdar, Vahid; Agio, Mario

doi:10.1166/jctn.2009.1259

Cited by 50 publications

(61 citation statements)

References 35 publications

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“…4 where the growing oxide plays a larger role in the case of the single-arm antennas. This observation is in good agreement with numeric results from Mohammadi et al [30] for copper nanostructures. The gap as coupling element perturbs the antenna dipole moment and thereby modifies the restoring force affecting the plasmon resonance.…”

Section: Resultssupporting

confidence: 93%

Oxide mediated spectral shifting in aluminum resonant optical antennas

Schwab¹,

Moosmann²,

Dopf³

et al. 2015

Opt. Express

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Abstract:As a key feature among metals showing good plasmonic behavior, aluminum extends the spectrum of achievable plasmon resonances of optical antennas into the deep ultraviolet. Due to degradation, a native oxide layer gives rise to a metal-core/oxide-shell nanoparticle and influences the spectral resonance peak position. In this work, we examine the role of the underlying processes by applying numerical nanoantenna models that are experimentally not feasible. Finite-difference time-domain simulations are carried out for a large variety of elongated single-arm and two-arm gap nanoantennas. In a detailed analysis, which takes into account the varying surface-to-volume ratio, we show that the overall spectral shift toward longer wavelengths is mainly driven by the higher index surrounding material rather than by the decrease of the initial aluminum volume. In addition, we demonstrate experimentally that this shifting can be minimized by an all-inert fabrication and subsequent proof-of-concept encapsulation.

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Section: Resultssupporting

confidence: 93%

Oxide mediated spectral shifting in aluminum resonant optical antennas

Schwab¹,

Moosmann²,

Dopf³

et al. 2015

Opt. Express

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“…aluminum, silver, gold, copper), in order to optimize the Purcell factor. Another important point is that the resonance needs to be in a spectral region where the dissipation in the metal is minimized [311]. This is a very active area of research at the moment: a recent computational study [309] for example has investigated how gold ''nanocones'' perform as optical antennas for metal enhanced fluorescence with respect to spheres and rods, highlighting how in these nanocones the longitudinal plasmon resonance can be tuned to shorter wavelengths with respect to rods (by increasing the cone angle), without compromising the Purcell Factor and the antenna efficiency.…”

Section: Surface Enhanced Fluorescencementioning

confidence: 99%

Physical properties of elongated inorganic nanoparticles

et al. 2011

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“…The input-output relationships between the ports are defined using S-parameters of the form where p and q are port numbers [31,32]. In a two-port network, 21 , represents the power received at port 2 from port 1, 11 and 22 represent the power reflected at ports 1 and 2 respectively. In practice, a low 11 would be desirable for an antenna and indicates very little power reflected at the input.…”

Section: The Single Nanoantennamentioning

confidence: 99%

“…However, 11 measurements do not discriminate between Ohmic losses and the desired radiation losses; hence, are rarely considered in isolation. In contrast, 21 , describes the power transferred from the transmitting to receiving antenna and is a better indicator of how well the device radiates. In this paper, the figure-of-merit is Power Enhancement, defined as the net power transmission through a 3D box enclosing the nanoantenna, normalised to the power that would have been injected by the source in a homogenous free space environment.…”

Section: The Single Nanoantennamentioning

confidence: 99%

“…Based on a comparison of dielectric properties within the Drude-Lorentz model, Al losses are among the lowest over the 350-440 nm spectral region, making it a sound choice for nanoantenna design. Aluminium based plasmonics also carries a number of benefits: it is considerably cheaper than gold, self-passivates with a roughly 2-3 nm aluminium oxide layer [20] and has relatively low absorbance over a large spectral range [21,22] In this paper Section 2 studies a single isolated antenna, considering the mechanism for enhancement and establishing the polarisation dependence. Section 3 shows results for 2 x 2 arrays under varying excitation conditions, with a particular focus on the enhancement and resonance.…”

Section: Introductionmentioning

confidence: 99%

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Polarization and mutual coupling effects in aluminum nanoantenna arrays

2015

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Abstract: This paper uses Finite Difference Time Domain (FDTD) modelling to study impact of varying the polarisation of the point source(s) on both the single aluminium dipole nanoantenna and a 2 x 2 array. Starting with the single dipole nanoantenna, this paper demonstrates the strong dependence of the Power Enhancement and resonance on the polarisation of the source by alternating between orthogonal polarisation states. With each element of the array excited by a single point source, the resonance, Power Enhancement and far field radiation patterns are observed as the polarisation of each source is rotated, in varying combinations. The results demonstrate that a unique far field radiation pattern is produced for each polarisation combination, which may lead to applications in sub-diffraction limit imaging and quantum optics. IntroductionThe antenna concept has existed for well over a century [1][2][3] and nanoantennas have now extended the technology into the optics regime; combining classical antenna theory with plasmonics to dramatically enhance the emission and absorption of light [4]. Nanoantennas are nanoscale devices which couple freely propagating light to localised surface plasmons and vice-versa. Applications of the technology range from imaging to photonic circuits and sensors [5][6][7][8][9]. When an optical emitter such as a quantum dot or fluorophore is brought into close proximity to a nanoantenna, Purcell enhanced emission can occur [4,10,11]. Alongside this, the nanoantenna shape will produce a particular pattern in the far field, termed the radiation pattern in classical antenna theory. If the antenna is part of a larger periodic array, the array element spacing can give rise to both radiation pattern shaping effects and surface wave propagation on the array; both of which have been widely studied in the RF literature[12] and the latter is termed Surface Lattice Resonances in the optics field [6,13]. An important and well-known effect in RF antenna arrays is that of mutual coupling. This is where interaction between neighbouring elements in the array modifies the characteristics of the individual antennas. The simplest manifestation of this is detuning of the antenna resonance, thus one cannot simply use the design of a single element to evaluate the resonance of an array. Mutual coupling will also depend strongly on the orientation of emitter near each antenna. This paper will explore these effects through Finite Difference Time Domain (FDTD) modelling [14] and will show how the array far field pattern and resonant wavelength can be used to determine the orientation of emitters [15,16] with respect to the nanoantenna arrays elements; this could find applications in single molecule fluorescence and quantum optics.

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Gold, Copper, Silver and Aluminum Nanoantennas to Enhance Spontaneous Emission

Cited by 50 publications

References 35 publications

Oxide mediated spectral shifting in aluminum resonant optical antennas

Oxide mediated spectral shifting in aluminum resonant optical antennas

Physical properties of elongated inorganic nanoparticles

Polarization and mutual coupling effects in aluminum nanoantenna arrays

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