arXiv subjects

Hidemasa Yamane

Publications and source records attributed to Hidemasa Yamane.

8 recordsLinked to original sources

arXiv2026

Local Chiral Optical Responses in Phthalocyanine Molecular Assemblies Revealed by Photoinduced Force Microscopy

Photoinduced force microscopy (PiFM) provides a force-based probe of nanoscale polarization-dependent molecular excitations. Here, we theoretically investigate PiFM images of zinc phthalocyanine assemblies using the discrete dipole approximation with nonlocal molecular susceptibilities. Under linearly polarized illumination, intermolecular dipole coupling splits the molecular resonance into bonding and antibonding modes. These modes produce distinct force distributions: bonding modes enhance signals at molecular termini, whereas antibonding modes localize responses in intermolecular regions, reflecting collective intermolecular polarization modes. Under circularly polarized illumination, intermolecular coupling and anisotropic molecular packing generate spatially varying local circular dichroism signals with enhanced asymmetric force factors. These results establish PiFM as a real-space probe of collective polarization modes and coupling-induced local chiral optical responses.

physics.optics↗

arXiv2026

Selective Remote Dissipation of an Off-resonant State via Indirect Driving

We show how local periodic driving can be used to control dissipation in a structured environment in a highly selective manner. As a minimal setting, we consider two discrete levels coupled to a one-dimensional tight-binding continuum with a finite bandwidth, where only one level is driven while the other remains undriven. Without driving, both bare energies are placed outside the static continuum band so that neither level decays. We demonstrate that the drive can nevertheless activate a selective remote dissipation channel: the undriven level acquires a finite decay rate, whereas the driven level can remain long-lived. The mechanism is clarified within Floquet theory. Periodic driving generates photon-assisted channels shifted by integer multiples of the drive frequency, effectively creating a ladder of drive-shifted continuum sidebands (Floquet channels). A decay channel for the undriven level opens once its bare energy overlaps an open sideband accessed via drive-enabled pathways; in the tight-binding example, the decay is strongly enhanced near the sideband edge due to the increased density of states. The dominant remote pathway is controlled by Bessel-weighted couplings and can be switched and strongly suppressed by tuning the drive amplitude. We verify these predictions by direct numerical integration of the time-dependent Schrödinger equation. We also formulate a complex-eigenvalue problem for the Floquet Hamiltonian by eliminating the continuum via a Brillouin--Wigner--Feshbach projection, and show that the pole-implied decay rate quantitatively reproduces the time-domain decay envelope.

quant-ph↗

arXiv2026

Terahertz Communications Using Effective-Medium-Slot Waveguides

All-dielectric effective-medium-clad waveguides have been widely exploited in terahertz communications owing to their extremely low loss, low dispersion, and broad bandwidth. In this work, we propose a substrateless effective-medium-slot waveguide. Additionally, we introduce a taper-free interface that allows terahertz waves to directly couple from a metallic hollow waveguide without requiring dielectric insertion. By engineering slot couplers with an effectivemedium channel for impedance and modal matching, the waveguide achieves a fractional 3-dB bandwidth of 40% with a maximum coupling efficiency of 90% in the WR-2.2 band (330-500 GHz). By employing a broadband uni-traveling-carrier photodiode transmitter and sub-harmonic mixer receivers, we achieve an aggregated data rate of 0.8 Tbit/s with quadrature amplitude modulation schemes across 14 channels from 330-600 GHz. The effective-medium-slot waveguide platform yields robust broadband coupling with enhanced mechanical protection, offering reliable interconnects for ultra-high-speed terahertz integrated systems.

physics.optics↗

arXiv2026

Resonant tunneling diode-integrated terahertz transceiver module for wireless communications

Terahertz bands enable ultra-broadband wireless communications but require compact, low-cost, and efficient transceiver modules. Conventional implementations based on metallic waveguides or silicon lenses suffer from high loss, bulkiness, and fabrication complexity. Here, we present a compact terahertz transceiver module enabled by a resonant tunneling diode (RTD) integrated with a photonic-electronic antenna chain. The RTD on InP is coupled to a modified Vivaldi antenna and an all-silicon effective-medium-clad waveguide, terminating in a rod antenna interfaced with a 3D-printed cyclic olefin copolymer lens. This architecture enables broadband directive radiation without matching networks or anti-reflection coatings. Packaged in a low-cost 3D-printed PLA enclosure, the module achieves realized gains of 28-33 dBi (E11x) and 30-33 dBi (E11y) across 220-330 GHz. As a receiver, it exhibits a noise voltage density of 5.6 x 10^-9 V/sqrt(Hz), a minimum noise equivalent power of 1.8 pW/sqrt(Hz), and an average responsivity of 6.8 kV/W. It supports error-free transmission up to 30 Gbit/s (OOK) and 80 Gbit/s (16-QAM) over 10 cm, and enables real-time uncompressed high-definition video streaming over 1 m. As a transmitter, it achieves error-free OOK transmission up to 12 Gbit/s at 332 GHz. These results demonstrate a promising terahertz transceiver architecture for 6G systems.

physics.optics↗

arXiv2026

Refractive Index Tuning of Terahertz Photonic Materials Based on a Stretchable Silicon Effective Medium

Dynamically tunable terahertz (THz) photonics requires low-loss dielectric platforms with practical, continuous control of refractive index. Here we present a mechanically reconfigurable THz photonic material platform: a monolithic, all-silicon (Si) stretchable effective medium whose refractive index is tuned by deformation. A 200 micrometer-thick high-resistivity single-crystal Si slab was patterned into a subwavelength spiral-spring through-hole lattice, rendering bulk Si mechanically compliant while preserving its low-loss dielectric response. THz time-domain spectroscopy demonstrates high transmission below 0.6 THz and reveals a monotonic decrease in the effective refractive index under uniaxial stretching. At 12.6% elongation, the effective index decreases by 6% and 8% for polarizations perpendicular and parallel to the stretch direction, respectively, thereby demonstrating deformation-induced, controllable anisotropy without a detectable increase in extinction. This structurally engineered bulk-Si approach offers a process-compatible route to mechanically tunable, low-loss THz components for adaptive wavefront and polarization control.

physics.optics↗

arXiv2020

Theoretical Analysis of Optically Selective Imaging in Photoinduced Force Microscopy

We present a theoretical study of the measurements of photoinduced force microscopy (PiFM) for composite molecular systems. Using the discrete dipole approximation, we calculate the self-consistent response electric field of the entire sample including the PiFM tip, substrate, and composite molecules. We demonstrate a higher sensitivity for the PiFM measurement on resonant molecules than by the previously obtained tip-sample distance dependency $z^{-4}$ owing of the multifold enhancement of the field between the localized electric field induced at the tip-substrate nanogap and the molecular polarization. The enhanced localized electric field induced at the tip-substrate nanogap in PiFM allows high-resolution observation of the forbidden optical electronic transition in dimer molecules. We investigated the wavelength dependence of PiFM for dimer molecules and obtained images at incident light wavelengths corresponding to allowed and forbidden transitions. We reveal that these PiFM images drastically change with the frequency-dependent spatial structures of the localized electric field vectors and resolve different types of nanoparticles beyond the resolution for the optically allowed transitions. This study demonstrates that PiFM provides multifaceted information based on microscopic interactions between nanomaterials and light.

physics.optics↗

arXiv2018

Dynamics of high-harmonic generation in terms of complex Floquet spectral analysis

High-harmonic generation (HHG) of a two-level-system driven by an intense monochromatic phase-locked laser is studied in terms of complex spectral analysis with the Floquet method. In contrast to the phenomenological approaches, this analysis deals with the whole process as a coherent quantum process based on microscopic dynamics. The spectral decomposition corresponding to the contributions of the Floquet resonance and dressed continuous states of the total system have been obtained. The calculated HHG spectrum exhibits the characteristic features of the HHG from solids. We found that the quantum interference of the Floquet resonance states is responsible for the transition from the adiabatic to the stationary regime in the HHG process and that the phase of the driving laser controls the dynamics of the HHG photon emission.

quant-ph↗

arXiv2017

Analysis of high-harmonic generation in terms of complex Floquet spectral analysis

Recent developments on intense laser sources is opening a new field of optical sciences. An intense coherent light beam strongly interacting with the matter causes a coherent motion of a particle, forming a strongly dressed excited particle. A photon emission from this dressed excited particle is a strong nonlinear process causing high-harmonic generation(HHG), where the perturbation analysis is broken down. In this work, we study a coherent photon emission from a strongly dressed excited atom in terms of complex spectral analysis in the extended Floquet-Hilbert-space. We have obtained the eigenstates of the total Hamiltonian with use of Feshbach-Brilloiun-Wigner projection method. In this extended space, the eigenstates of the total Hamiltonian consisting of the radiation field and the atom system have complex eigenvalues whose imaginary part represents the decay rate. Time evolution of the system is represented by the complex eigenvector expansion so that the correlation dynamics between the photon and the atom is fully taken into account. The HHG is interpreted as the irreversible spontaneous photon emission due to the resonance singularity in terms of the multiple Floquet states that are generated by periodic external field. We have found that the interference between the emitted photons over the different Floquet states causes spatial pulse emission correlated with the decay process of the excited atom.

quant-ph↗