Synthetic optical holography for rapid nanoimaging

Schnell, Martin; Carney, P. Scott; Hillenbrand, Rainer

doi:10.1038/ncomms4499

Cited by 94 publications

(78 citation statements)

References 67 publications

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“…The h-BN (7 nm)-graphene-h-BN (46 nm) stack assembled by the polymer-free van der Waals assembly technique 22 lies on top of an oxidized silicon wafer, used as a backgate. This stack is etched into a triangle and is electrically side-contacted with metal electrodes 22 .We image propagating plasmons with a scattering-type scanning near-field optical microscope 25,26 (s-SNOM), similar to several recent studies of graphene plasmons 23,24,[27][28][29][30][31] . A schematic of the s-SNOM interacting with the graphene device is shown in Fig.…”

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confidence: 97%

Highly confined low-loss plasmons in graphene–boron nitride heterostructures

et al. 2014

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Graphene plasmons were predicted to possess simultaneous ultrastrong field confinement and very low damping, enabling new classes of devices for deep-subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches. Although all of these great prospects require low damping, thus far strong plasmon damping has been observed, with both impurity scattering and many-body effects in graphene proposed as possible explanations. With the advent of van der Waals heterostructures, new methods have been developed to integrate graphene with other atomically flat materials. In this Article we exploit near-field microscopy to image propagating plasmons in high-quality graphene encapsulated between two films of hexagonal boron nitride (h-BN). We determine the dispersion and plasmon damping in real space. We find unprecedentedly low plasmon damping combined with strong field confinement and confirm the high uniformity of this plasmonic medium. The main damping channels are attributed to intrinsic thermal phonons in the graphene and dielectric losses in the h-BN. The observation and in-depth understanding of low plasmon damping is the key to the development of graphene nanophotonic and nano-optoelectronic devices.

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confidence: 97%

Highly confined low-loss plasmons in graphene–boron nitride heterostructures

et al. 2014

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“…In addition, in synthetic holography, the key element is the presence of a synthetic reference wave, analogous to a plane reference wave in wide-field off-axis holography, that is generated by adding a linearly moving reference mirror to the microscope setup. 8 The latter introduces a linear temporal/spatial modulation in the phase of interference term. In the proposed system, since no reference beam can be defined, the temporal/spatial phase modulation is synthetized inside the phase ϕ of interference term γ by means of a synthetic tilt of the sample.…”

mentioning

confidence: 99%

“…[4][5][6][7] Although the features of wide-field digital holography have confirmed this technique as a relevant tool for imaging, only recently this method has been implemented in optical scanning microscopy. 8 In the latter, named synthetic optical holography (SOH), a point detector is employed, replacing CCD cameras, in order to encode the phase across the whole image. It was demonstrated that SOH is a method technically simple and fast for phase imaging.…”

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confidence: 99%

Synthetic holography based on scanning microcavity

Donato

Farina

2015

AIP Advances

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Synthetic optical holography (SOH) is an imaging technique, introduced in scanning microscopy to record amplitude and phase of a scattered field from a sample. In this paper, it is described a novel implementation of SOH through a lens-free low-coherence system, based on a scanning optical microcavity. This technique combines the low-coherence properties of the source with the mutual interference of scattered waves and the resonant behavior of a micro-cavity, in order to realize a high sensitive imaging system. Micro-cavity is compact and realized by approaching a cleaved optical fiber to the sample. The scanning system works in an open-loop configuration without the need for a reference wave, usually required in interferometric systems. Measurements were performed over calibration samples and a lateral resolution of about 1 μm is achieved by means of an optical fiber with a Numerical Aperture (NA) equal to 0.1 and a Mode Field Diameter (MDF) of 5.6 μm.

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“…The radar community developed an analogous concept [3] that instead assembles a hologram pointwise using a local electronic oscillator as a reference to avoid the impossible task of physically interfering the object field with a similarly scaled reference. We here introduce synthetic optical holography (SOH) [4], which uses a similar concept to produce an optical digital hologram. This is desirable in cases where an appropriate reference field is inconvenient or impossible to produce using conventional optics.…”

Section: Introductionmentioning

confidence: 99%

Synthetic Optical Holography

Deutsch¹,

Schnell²,

Hillenbrand³

et al. 2014

Classical Optics 2014

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In holography, spatially dependent amplitude and phase information about an unknown signal is encoded in an intensity image by means of interference with a known reference wave. In analogy with methods developed for radar, we introduce synthetic optical holography (SOH) for quantitative, phase-resolved imaging. In SOH, the reference wave of a digital hologram is defined point by point, uniquely combining technical simplicity, fast phase imaging and broadband operation from visible to terahertz frequencies within a single setup. To illustrate the advantage of SOH, we use it in conjunction with a scattering-type near-field optical microscope to perform near-field holography, improving the speed of operation by more than an order of magnitude while significantly simplifying the experiment. OCIS codes: (090.1995) Digital holography; (170.5810) Scanning microscopy. BackgroundHolography [1] provides a straightforward way to encode amplitude and phase information about an unknown field in an intensity measurement. In digital Fourier holography, [2] the image of an unknown object field is superimposed on a known planar reference wave of the form U r = Ae ik·r on a CCD, where k is the wavevector with magnitude k = 2π/λ . The intensity on the CCD can then be expressed in the spatial Fourier domain aswhere the tilde indicates the Fourier transform with respect to position, δ is the Dirac delta function, C = |Ũ S | 2 , and k is the in-plane component of the wavevector. The first two terms of this equation are centered at q = 0, and contain no phase information. The last two terms are offset from the origin by q = ± k respectively. Either of these terms may be filtered out, shifted to the origin, and inverse Fourier transformed to retrieve the object field with reduced spatial bandwidth compared to the original intensity data. This holographic technique constrains us to use plane wave references that can be physically produced using far-field optics. The radar community developed an analogous concept [3] that instead assembles a hologram pointwise using a local electronic oscillator as a reference to avoid the impossible task of physically interfering the object field with a similarly scaled reference. We here introduce synthetic optical holography (SOH) [4], which uses a similar concept to produce an optical digital hologram. This is desirable in cases where an appropriate reference field is inconvenient or impossible to produce using conventional optics. Synthetic Optical HolographyFigure 2(a) is a sketch of a basic synthetic optical holography setup. Coherent light is focused on a sample, which back-scatters light with unknown amplitude and phase into a Michelson interferometer, where it is combined with a planar reference to give a single intensity measurement on a point detector. As the sample is translated to address each transverse coordinate, the reference phase is changed linearly, typically by translating the reference mirror with a peizoelectric device. The resulting equivalent reference field can be described as a...

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Synthetic optical holography for rapid nanoimaging

Cited by 94 publications

References 67 publications

Highly confined low-loss plasmons in graphene–boron nitride heterostructures

Highly confined low-loss plasmons in graphene–boron nitride heterostructures

Synthetic holography based on scanning microcavity

Synthetic Optical Holography

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