We present reflective plasmonic colors based on the concept of localized surface plasmon resonances (LSPR) for plastic consumer products. In particular, we bridge the widely existing technological gap between clean-room fabricated plasmonic metasurfaces and the practical call for large-area structurally colored plastic surfaces robust to daily life handling. We utilize the hybridization between LSPR modes in aluminum nanodisks and nanoholes to design and fabricate bright angle-insensitive colors that may be tuned across the entire visible spectrum.

The possibility of combining atomic and plasmonic resonances opens new avenues for tailoring the spectral properties of materials. Following the rapid progress in the field of plasmonics, it is now possible to confine light to unprecedented nanometre dimensions, enhancing light-matter interactions at the nanoscale. However, the resonant coupling between the relatively broad plasmonic resonance and the ultra-narrow fundamental atomic line remains challenging. Here we demonstrate a resonantly coupled plasmonic-atomic platform consisting of a surface plasmon resonance and rubidium ( 85 Rb) atomic vapour. Taking advantage of the Fano interplay between the atomic and plasmonic resonances, we are able to control the lineshape and the dispersion of this hybrid system. Furthermore, by exploiting the plasmonic enhancement of light-matter interactions, we demonstrate alloptical control of the Fano resonance by introducing an additional pump beam.

Internal photoemission of charged carriers from metal to semiconductors plays an important role in diverse fields such as sub-bandgap photodetectors and catalysis. Typically, the quantum efficiency of this process is relatively low, posing a stringent limitation on its applicability. Here, we show that the efficiency of hot carrier injection from a metal into a semiconductor across a Schottky barrier can be enhanced by as much as an order of magnitude in the presence of surface roughness on the scale of a few atomic layers. Our results are obtained using a simple semianalytical theory and indicate that properly engineered plasmonic-assisted internal photoemission photodetectors can be a viable alternative in silicon photonics. Other applications, such as plasmonic-enhanced photocatalysis, can also benefit from these results.

We present a comprehensive experimental and theoretical study on the near- and far-field properties of plasmonic oligomers using radially and azimuthally polarized excitation. These unconventional polarization states are perfectly matched to the high spatial symmetry of the oligomers and thus allow for the excitation of some of the highly symmetric eigenmodes of the structures, which cannot be excited by linearly polarized light. In particular, we study hexamer and heptamer structures and strikingly find very similar optical responses, as well as the absence of a Fano resonance. Furthermore, we investigate the near-field distributions of the oligomers using near-field scanning optical microscopy (NSOM). We observe significantly enhanced near-fields, which arise from efficient excitation of the highly symmetric eigenmodes by the radially and azimuthally polarized light fields. Our study opens up possibilities for tailored light-matter interaction, combining the design freedom of complex plasmonic structures with the remarkable properties of radially and azimuthally polarized light fields.

Plasmonic enhanced Schottky photodetectors operating on the basis of the internal photoemission process are becoming an alternative for the more conventional photodetectors based on interband transitions for light detection in the infrared. This is because such detectors typically consist of silicon and CMOS compatible metals, thus, allowing low cost and large scale fabrication. Most of the reports so far were focused on measuring the responsivity of the device. Here, we provide a detailed analysis for the optimization of internal photoemission based devices in terms of figure of merits such as signal-to-noise ratio (SNR) and noise equivalent power (NEP). Following the analysis, we experimentally demonstrate the operation of pyramidally shaped, silicon-based, internal photoemission detectors in the mid-infrared. The measured devices are capable of photodetection at wavelengths up to ∼2.5 μm. This paves the way for the use of plasmonic enhanced silicon photodetectors for a broad range of applications including mid-IR circuitry and biochemical sensing.

Recent experiments have shown that the plasmonic assisted internal photoemission from a metal to silicon can be significantly enhanced by introducing a monolayer of graphene between the two media. This is despite the limited absorption in a monolayer of undoped graphene (∼πα=2.3%). Here we propose a physical model where surface plasmon polaritons enhance the absorption in a single-layer graphene by enhancing the field along the interface. The relatively long relaxation time in graphene allows for multiple attempts for the carrier to overcome the Schottky barrier and penetrate into the semiconductor. Interface disorder is crucial to overcome the momentum mismatch in the internal photoemission process. Our results show that quantum efficiencies in the range of few tens of percent are obtainable under reasonable experimental assumptions. This insight may pave the way for the implementation of compact, high efficiency silicon based detectors for the telecom range and beyond.

Although metals are commonly shiny and highly reflective, we here show that thin metal films appear black when deposited on a dielectric with antireflective moth-eye nanostructures. The nanostructures were tapered and close-packed, with heights in the range 300-600 nm, and a lateral, spatial frequency in the range 5–7 μm−1. A reflectance in the visible spectrum as low as 6%, and an absorbance of 90% was observed for an Al film of 100 nm thickness. Corresponding experiments on a planar film yielded 80% reflectance and 20% absorbance. The observed absorbance enhancement is attributed to a gradient effect causing the metal film to be antireflective, analogous to the mechanism in dielectrics and semiconductors. We find that the investigated nanostructures have too large spatial frequency to facilitate efficient coupling to the otherwise non-radiating surface plasmons. Applications for decoration and displays are discussed.

We demonstrate the design, fabrication, and experimental characterization of a long range surface plasmon polariton waveguide that is compatible with complementary metal-oxide semiconductor backend technology. The structure consists of a thin aluminum strip embedded in amorphous silicon. This configuration offers a symmetric environment in which surface plasmon polariton modes undergo minimal loss. Furthermore, the plasmonic mode profile matches the modes of the dielectric (amorphous silicon) waveguide, thus allowing efficient coupling between silicon photonics and plasmonic platforms. The propagation length of the plasmonic waveguide was measured to be about 27 μm at the telecom wavelength around 1550 nm, in good agreement with numerical simulations. As such, the waveguide features both tight mode confinement and decent propagation length. On top of its photonic properties, placing a metal within the structure may also allow for additional functionalities such as photo-detection, thermo-optic tuning, and electro-optic control to be implemented.