Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userClocking plasmon nanofocusing by THz near-field streaking
122
0
0.0
(
0
)
Added by
Benjamin Schr\\\"oder
Publication date
2020
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We apply terahertz (THz) near-field streaking in a nanofocusing geometry to investigate plasmon polariton propagation on the shaft of a conical nanotip. By evaluating the delay between a streaking spectrogram for plasmon-induced photoemission with a measurement for direct apex excitation, we obtain an average plasmon group velocity, which is in agreement with numerical simulations. Combining plasmon-induced photoemission with THz near-field streaking facilitates extensive control over localized photoelectron sources for time-resolved imaging and diffraction.
rate research
Read More
We developed THz-resonant scanning probe tips, yielding strongly enhanced and nanoscale confined THz near fields at their tip apex. The tips with length in the order of the THz wavelength ({lambda} = 96.5 {mu}m) were fabricated by focused ion beam (FIB) machining and attached to standard atomic force microscopy (AFM) cantilevers. Measurements of the near-field intensity at the very tip apex (25 nm radius) as a function of tip length, via graphene-based (thermoelectric) near-field detection, indicate their first and second order geometrical antenna resonances for tip length of 33 and 78 {mu}m, respectively. On resonance, we find that the near-field intensity is enhanced by one order of magnitude compared to tips of 17 {mu}m length (standard AFM tip length), which is corroborated by numerical simulations that further predict remarkable intensity enhancements of about 107 relative to the incident field. Because of the strong field enhancement and standard AFM operation of our tips, we envision manifold and straightforward future application in scattering-type THz near-field nanoscopy and THz photocurrent nanoimaging, nanoscale nonlinear THz imaging, or nanoscale control and manipulation of matter employing ultrastrong and ultrashort THz pulses.
We report on the global temporal pulse characteristics of individual harmonics in an attosecond pulse train by means of photo-electron streaking in a strong low-frequency transient. The scheme allows direct retrieval of pulse durations and first order chirp of individual harmonics without the need of temporal scanning. The measurements were performed using an intense THz field generated by tilted phase front technique in LiNbO_3 . Pulse properties for harmonics of order 23, 25 and 27 show that the individual pulse durations and linear chirp are decreasing by the harmonic order.
Vibrational ultrastrong coupling (USC), where the light-matter coupling strength is comparable to the vibrational frequency of molecules, presents new opportunities to probe the interactions of molecules with zero-point fluctuations, harness cavity-enhanced chemical reactions, and develop novel devices in the mid-infrared regime. Here we use epsilon-near-zero nanocavities filled with a model polar medium (SiO$_2$) to demonstrate USC between phonons and gap plasmons. We present classical and quantum mechanical models to quantitatively describe the observed plasmon-phonon USC phenomena and demonstrate a splitting of up to 50% of the resonant frequency. Our wafer-scale nanocavity platform will enable a broad range of vibrational transitions to be harnessed for USC applications.
We report on the strong coupling between inorganic quantum well excitons and surface plasmons. For that purpose a corrugated silver film was deposited on the top of a heterostructure consisting of GaAs/GaAlAs quantum wells. The formation of plasmon/heavy-hole exciton/light-hole exciton mixed states is demonstrated with reflectometry experiments. The interaction energies amount to 21 meV for the plasmon/light-hole exciton and 22 meV for the plasmon/heavy-hole exciton. Some particularities of the plasmon-exciton coupling were also discussed and qualitatively related to the plasmon polarization.
Modern scattering-type scanning near-field optical microscopy (s-SNOM) has become an indispensable tool in material research. However, as the s-SNOM technique marches into the far-infrared (IR) and terahertz (THz) regimes, emerging experiments sometimes produce puzzling results. For example, anomalies in the near-field optical contrast have been widely reported. In this Letter, we systematically investigate a series of extreme subwavelength metallic nanostructures via s-SNOM near-field imaging in the GHz to THz frequency range. We find that the near-field material contrast is greatly impacted by the lateral size of the nanostructure, while the spatial resolution is practically independent of it. The contrast is also strongly affected by the connectivity of the metallic structures to a larger metallic ground plane. The observed effect can be largely explained by a quasi-electrostatic analysis. We also compare the THz s-SNOM results to those of the mid-IR regime, where the size-dependence becomes significant only for smaller structures. Our results reveal that the quantitative analysis of the near-field optical material contrasts in the long-wavelength regime requires a careful assessment of the size and configuration of metallic (optically conductive) structures.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
