Electron energy loss and induced photon emission in photonic crystals

Abajo, F. Javier García de; Blanco, L. A.

doi:10.1103/physrevb.67.125108

Cited by 25 publications

(18 citation statements)

References 38 publications

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“…This superradiant emission is an underlying principle of free-electron lasers and it can be exploited to produce intense THz emission [7], in good agreement with theoretical calculations [11,12]. SPR emission has been also observed from photonic [13,14] and plasmonic [15,16] crystals with periods of the order of the light wavelength.…”

Section: Introductionsupporting

confidence: 80%

Interference of surface plasmons and Smith-Purcell emission probed by angle-resolved cathodoluminescence spectroscopy

2015

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We investigate the interplay between geometrical lattice resonances and surface plasmons mediating the emission of Smith-Purcell visible light via angle-resolved cathodoluminescence spectroscopy. We observe strong modulations in the dispersion curves of Smith-Purcell radiation (SPR) when they intersect the surface plasmons of silver gratings using a 200-kV transmission electron microscope. The decay of the plasmons away from the grating is directly probed by controlling the electron-beam position relative to the sample surface with nanometer precision. Our measurements are in excellent agreement with numerical simulations, clearly revealing the presence of characteristic Fano profiles resulting from the interference of the light continuum and the discrete plasmon states for each direction of emission. The intensity anomaly in the SPR emission pattern can be well explained from the geometrical consideration of the intersections between the dispersion planes of the SPR and surface plasmon polariton (SPP). A strong and directional SPR beam can be realized under the condition that the SPR dispersion plane comes in contact with the band edge of the SPP dispersion plane.

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Section: Introductionsupporting

confidence: 80%

Interference of surface plasmons and Smith-Purcell emission probed by angle-resolved cathodoluminescence spectroscopy

2015

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“…This approach was followed by Pendry and Martín-Moreno (1994) to explain the ∼ 8 eV loss feature measured by Howie and Walsh (1991) in aggregates of small aluminum particles. Their simulations were accompanied by a complex series of spectral features that subsequent analysis by García de Abajo and Blanco (2003) demonstrated to be due to numerical inaccuracies. In fact, the loss spectrum for small filling fraction (f = 0.06) of an array of equally-spaced aluminum spheres already shows a single ∼ 8.5 eV feature (García de Abajo and Blanco, 2003) [see Fig.…”

Section: F Composite Materialsmentioning

confidence: 99%

Optical excitations in electron microscopy

2010

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This review discusses how low-energy valence excitations created by swift electrons can render information on the optical response of structured materials with unmatched spatial resolution. Electron microscopes are capable of focusing electron beams on subnanometer spots and probing the target response either by analyzing electron energy losses or by detecting emitted radiation. Theoretical frameworks suited to calculate the probability of energy loss and light emission ͑cathodoluminescence͒ are reconsidered and compared with experimental results. More precisely, a quantum-mechanical description of the interaction between the electrons and the sample is discussed, followed by a powerful classical dielectric approach that can be applied in practice to more complex systems. The conditions are assessed under which classical and quantum-mechanical formulations are equivalent. The excitation of collective modes such as plasmons is studied in bulk materials, planar surfaces, and nanoparticles. Light emission induced by the electrons is shown to constitute an excellent probe of plasmons, combining subnanometer resolution in the position of the electron beam with nanometer resolution in the emitted wavelength. Both electron energy-loss and cathodoluminescence spectroscopies performed in a scanning mode of operation yield snapshots of plasmon modes in nanostructures with fine spatial detail as compared to other existing imaging techniques, thus providing an ideal tool for nanophotonics studies.

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“…Contrary to the work of Sapienza et al [2] where the LDOS is measured within the band gap of a dielectric- material photonic-crystal device, with the electron beam acting directly as a broadband dipole source, known as coherent excitation [15,16], our measurements should more likely originate from incoherent excitation consisting in the creation and relaxation of many electron-hole pairs down to the active material of the photonic structure, namely quantum wells (QWs)and subsequent radiative recombination [17]. In some cases coherent emission processes can also be observed above the semiconductor band gap emission [18] and photon correlation experiments then become necessary to identify the coherent and incoherent contributions to the signal [19].…”

mentioning

confidence: 65%