Nanostructured Spintronic Emitters for Polarization-Textured and Chiral Broadband THz Fields

Schulz, Dominik; schwager, benjamin; Berakdar, J.

doi:10.1021/acsphotonics.1c01693

Cited by 8 publications

(11 citation statements)

References 59 publications

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“…7 Broadband THz pulses have also revolutionized spectroscopy and imaging in the THz frequency range. 8 Advanced spectroscopy and imaging now also require control of the spatial structure of THz pulses [9][10][11] and their waveform. 12 Structured THz beams can be formed with the help of phase plates, spatial light modulators, polarizers and lenses, [13][14][15][16][17][18][19] however for broadband THz pulses, this approach is limited in bandwidth and efficiency.…”

Section: Textmentioning

confidence: 99%

Terahertz Pulse Generation with Binary Phase Control in Nonlinear InAs Metasurface

et al. 2022

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The effect of terahertz (THz) pulse generation has revolutionized broadband coherent spectroscopy and imaging at THz frequencies. However, THz pulses typically lack spatial structure, whereas structured beams are becoming essential for advanced spectroscopy applications. Nonlinear optical metasurfaces with nanoscale THz emitters can provide a solution by defining the beam structure at the generation stage. We develop a nonlinear InAs metasurface consisting of nanoscale optical resonators for simultaneous generation and structuring of THz beams. We find that THz pulse generation in the resonators is governed by optical rectification. It is more efficient than in ZnTe crystals, and it allows us to control the pulse polarity and amplitude, offering a platform for realizing binary-phase THz metasurfaces. To illustrate this capability, we demonstrate an InAs metalens, which simultaneously generates and focuses THz pulses. The control of spatiotemporal structure using nanoscale emitters opens doors for THz beam engineering and advanced spectroscopy and imaging applications.

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Section: Textmentioning

confidence: 99%

Terahertz Pulse Generation with Binary Phase Control in Nonlinear InAs Metasurface

et al. 2022

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“…Here, is the amplitude of the electric field, is equal to the topological charge q , and are the unit vectors along (more details about the simulations are in “ Methods ” section). For the case of , the topology of the STEs becomes trivial 23 , for example, in this case the STEs magnetizations in Fig. 1 a point all such that (azimuthal structure) or radially (radial structure).…”

Section: Metastructure Of Stesmentioning

confidence: 99%

“…The emitted THz fields are then radially or azimuthally polarized. The latter, for instance, has only a transverse component 23 . Hence, imprinting a topology onto the STEs allows the controlled coherent buildup of transverse and longitudinal components of the emitted radiation (the field components and the resulting SC dynamics are discussed below, e.g., in Fig.…”

Section: Metastructure Of Stesmentioning

confidence: 99%

“…Experimentally, there have been remarkable advances in the generation of THz radiation exploiting spin-dependent transport in layered spintronic elements (hence, the name STEs) 17 – 23 . The basic unit (illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the inverse spin Hall effect, a decaying charge current density is generated leading to the THz emission ( is the magnetization direction of the FM). Metastructures of STEs 23 (such as those shown in Fig. 1 ) render possible a sub-wavelength spatial texturing of the polarization properties of the propagating THz field.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spatio-temporal superconducting dynamics driven by THz fields from topological spintronic terahertz emitters

Niedzielski

Schulz

Berakdar

2022

Sci Rep

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Metastructures of spintronic THz emitters can be engineered to have a well-defined topology characterized by a topological charge. The emitted THz radiation possesses a phase-locked transversal and longitudinal components with the ratio of which being tunable by the topological charge of the underlying metastructure. The THz fields so produced are employed to drive and spatio-temporally modulate the superconducting order parameter in a type II superconductor. Using a time-dependent Landau-Ginzburg approach, it is demonstrated how the topology of the THz fields is reflected in a texturing of the superconducting phase and density. Full numerical simulations illustrate the emergence and the nanoscale steering of Abrikosov vortices as well as the local modification of the superconducting density and transport properties of nanoscale samples with different geometries. The study highlights the potential of metamaterials based on spintronic THz emitters as a coherent source for spatially and vectorially modulated THz radiation.

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InAs Terahertz Metalens Emitter for Focused Terahertz Beam Generation

Jung,

Brener,

Addamane

et al. 2024

Advanced Photonics Research

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Metasurfaces have opened doors to combining multiple photonic functionalities in a single compact device. In particular, the ability to generate short terahertz (THz) pulses with precise wavefront engineering in a single THz metasurface redefined the role metasurfaces can play in THz systems. Here, an InAs metalens emitter which generates and focuses a THz pulse beam is demonstrated using a 130 nm thick InAs metasurface designed as a binary‐phase Fresnel zone plate. The THz beam is focused to a spot of ≈430 μm at 1 THz with a short focal length of 5 mm and large numerical aperture of 0.5. Nanoscale InAs Mie resonators comprising the metasurface enable THz generation with an amplitude as high as 20 times compared to plasmonic THz emitters and several times compared to a 1 mm thick ZnTe crystal. This InAs metasurface emitter provides a new paradigm for designing THz imaging, spectroscopy, and communication systems, where THz beam generation and shaping are performed with a single device without compromising the generation efficiency, while eliminating losses and avoiding limitations of phase matching of conventional nonlinear optics approaches.

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Nanostructured Spintronic Emitters for Polarization-Textured and Chiral Broadband THz Fields

Cited by 8 publications

References 59 publications

Terahertz Pulse Generation with Binary Phase Control in Nonlinear InAs Metasurface

Terahertz Pulse Generation with Binary Phase Control in Nonlinear InAs Metasurface

Spatio-temporal superconducting dynamics driven by THz fields from topological spintronic terahertz emitters

InAs Terahertz Metalens Emitter for Focused Terahertz Beam Generation

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