High quality factor phase gradient metasurfaces

Lawrence, Mark; Barton, David R.; Dixon, Jefferson; Song, Jung Hwan; Groep, Jorik van de; Brongersma, Mark L.; Dionne, Jennifer A.

doi:10.1038/s41565-020-0754-x

Cited by 136 publications

(123 citation statements)

References 41 publications

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“…Analysis of the near-fields reveal larger local electric field rotation within the [Pt/Co] 2 layers with linearly polarized excitation for single-crystalline Si metasurfaces compared to the amorphous Si case due to higher field strengths ( Figure S11, Supporting Information). Significantly enhanced electric near-field intensities and local electric field rotation with higher-quality-factor resonances [55] may also be obtained via symmetry breaking in biperiodic lattices of nanodisk resonators. [43,50] Moreover, designs in which the ferromagnetic layer itself is patterned into arrays, channels, or racetrack architectures could minimize radiative damping of p m modes.…”

mentioning

confidence: 99%

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]_N Films

Abendroth

Solomon

Barton

et al. 2020

Advanced Optical Materials

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materials, i.e., Faraday and Kerr effects, and magnetic circular dichroism (MCD). Circularly polarized light (CPL) pulses may also induce transient effective magnetic fields via the inverse Faraday effect (IFE), used to excite coherent spin precession at GHz and THz frequencies. [7,8] Of particular interest for manipulating magnetic order at ultrafast timescales with CPL is all-optical helicity-dependent switching (AO-HDS), which has been observed in ferromagnetic, ferrimagnetic, and granular thin films that exhibit perpendicular magnetic anisotropy. [9-12] However, contributions from MCD and the IFE to AO-HDS are difficult to deconvolve, [13-17] and understanding all-optical switching remains a challenging and widely debated topic in photonics and magnetism. [13,18-20] Enhancing local electric field rotation with CPL excitation could provide mechanistic insight, elucidate strategies toward faster and more efficient helicity-mediated switching with high spatial resolution, [21,22] and increase overall MO response for light-assisted reading and writing, essential for high-density on-chip integration. [23] Efforts to enhance MO effects below the diffraction limit and to advance the tunability of photon-electron spin interactions have been dominated by magnetoplasmonic approaches, which use localized surface plasmon resonances in metallic nanostructures or propagating surface plasmon polaritons at metal-dielectric interfaces. [24-32] For example, gold nanoparticle antennas have been used to achieve nanoconfined all-optical switching in TbFeCo films. [33] More recently, plasmon-mediated enhancement of the IFE by two orders of magnitude was shown to realize sub-THz spin precession confined within 100 nm thick regions of GdYbBIG. [34] However, plasmonic metals suffer from high intrinsic losses, and excessive heating could limit their performance near optical frequencies. Alternatively, greater efficiency could be realized with low-loss dielectric nanostructures fabricated from high-index materials that offer additional control over phase and polarization of light by virtue of their electric and magnetic Mie modes. [35-38] Specifically, helicity-preserving metasurfaces composed of sub-wavelength, 2D dielectric disk arrays have received significant attention for supporting highly twisted electromagnetic near-fields. [39-45] All-optical control and detection of magnetic states for high-density recording necessitate nanophotonic approaches to amplify local light intensity below the diffraction limit. Sculpting the near-field phase and polarization can additionally strengthen magneto-optical effects that rely on circularly polarized pulses, such as all-optical helicity-dependent switching, imaging, and spin-wave excitation. Here, high-refractive-index dielectric nanoantennas illuminated with circularly polarized light resonantly enhance local electric field rotation by more than sixfold within [Pt/Co] N thin films. Sub-wavelength arrays of amorphous Si nanodisks, or metasurfaces, patterned on perpendicularly magnetized film...

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confidence: 99%

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]_N Films

Abendroth

Solomon

Barton

et al. 2020

Advanced Optical Materials

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“…Second, wavelength-sized resonators have long been contended with low quality factors as a result of their small azimuthal modal order. However, recent breakthroughs in engineering of high-Q plasmonic resonators [33] or Mie resonators [34] from silicon nanoantennas [35] or bound states and quasi-bound states in the continuum (quasi-BICs) [36] have showcased compelling free-space candidates that now routinely reach quality factors on the order of few hundreds to few thousands, albeit in electronically passive structures that do not necessitate integration with microwave metallic waveguides that can introduce significant losses and lower the performance.…”

Section: Intensity Out δω Resmentioning

confidence: 99%

Gigahertz free-space electro-optic modulators based on Mie resonances

Benea-Chelmus

Mason

Meretska

et al. 2021

Preprint

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Electro-optic modulators from non-linear χ(2) materials are essential for sensing, metrology and telecommunications because they link the optical domain with the microwave domain. At present, most geometries are suited for fiber applications. In contrast, architectures that modulate directly free-space light at gigahertz (GHz) speeds have remained very challenging, despite their dire need for active free-space optics, in diffractive computing or for optoelectronic feedback to free-space emitters. They are typically bulky or suffer from much reduced interaction lengths. Here, we employ an ultrathin array of sub-wavelength Mie resonators that support quasi bound states in the continuum (BIC) as a key mechanism to demonstrate electro-optic modulation of free-space light with high efficiency at GHz speeds. Our geometry relies on hybrid silicon-organic nanostructures that feature low loss (Q = 550 at λres = 1594 nm) while being integrated with GHz-compatible coplanar waveguides. We maximize the electro-optic effect by using high-performance electro-optic molecules (whose electro-optic tensor we engineer in-device to exploit r33 = 100 pm/V) and by nanoscale optimization of the optical modes. We demonstrate both DC tuning and high speed modulation up to 5 GHz (fEO,-3 dB = 3 GHz) and shift the resonant frequency of the quasi-BIC by Δλres =11 nm, surpassing its linewidth. We contrast the properties of quasi-BIC modulators by studying also guided mode resonances that we tune by Δλres=20 nm. Our approach showcases the potential for ultrathin GHz-speed free-space electro-optic modulators.

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“…The AR metasurfaces are engraved on input and output waveguide facets in a periodic manner and consist of parabolic inclusions, as shown in Figure 1e. As compared to high quality factor dielectric gradient index metasurfaces, [ 40 ] here we aim to obtain broad spectrum performance of proposed metasurface‐on‐facet. We report on metasurface on waveguide facet acting as the near‐IR AR structure resulting in waveguide transparency effect 2.21 times higher as compared to untreated waveguide facets.…”

Section: Introductionmentioning

confidence: 99%

On‐Chip Metasurface‐on‐Facets for Ultra‐High Transmission through Waveguides in Near‐Infrared

Falek

Katiyi

Greenberg

et al. 2021

Advanced Optical Materials

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Nature has long inspired scientists and engineers to develop transparent surfaces via constructing anti‐reflective surfaces. In absence of anti‐reflection (AR) coating, silicon reflects about 35% of light for a single interface air−silicon. Here, inspired by jellyfish anti‐reflective eyes, a man‐made anti‐reflective surface on the facet of the waveguide is proposed and demonstrated for waveguides transparency in near‐infrared. The optimized metamaterial with unit cells of 560 × 560 nm shows transparency of 2.6 times better as compared to the waveguide with blank facet. Metasurfaces are milled on the waveguides facets with a focused ion beam. Silicon‐on‐insulator waveguides are tested with an inline set‐up. Far‐field scattering diagrams reveal that it is the special geometry of the unit cells of the engraved metamaterial, which can be associated with the directional scattering resulting in combined effect: on one hand the ultra‐high transparency of the device and on the other hand the efficient coupling to the low‐order modes due to the focusing dielectric nano‐antennas effect. Reported here waveguide facets as AR metamaterials on a chip, opens up opportunities to engineer transparent on‐chip devices with high coupling efficiency for diverse applications from sensing to quantum technologies.

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High quality factor phase gradient metasurfaces

Cited by 136 publications

References 41 publications

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]_N Films

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]_N Films

Gigahertz free-space electro-optic modulators based on Mie resonances

On‐Chip Metasurface‐on‐Facets for Ultra‐High Transmission through Waveguides in Near‐Infrared

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High quality factor phase gradient metasurfaces

Cited by 136 publications

References 41 publications

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]N Films

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]N Films

Gigahertz free-space electro-optic modulators based on Mie resonances

On‐Chip Metasurface‐on‐Facets for Ultra‐High Transmission through Waveguides in Near‐Infrared

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Product

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Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]_N Films

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]_N Films