arxiv: 2605.05918 · v1 · submitted 2026-05-07 · ⚛️ physics.optics

Recognition: unknown

Thermally reconfigurable extraordinary terahertz transmission using vanadium dioxide

S. Hadi Badri , Hadi Soofi , Sanam Saeidnahaei S

Authors on Pith no claims yet

Pith reviewed 2026-05-08 06:45 UTC · model grok-4.3

classification ⚛️ physics.optics

keywords reconfigurable metasurfacevanadium dioxideterahertz transmissionphase change materialextraordinary transmissionannular aperturesthermal tuning

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The pith

Annular vanadium dioxide inside gold apertures enables thermal shifting of extraordinary terahertz transmission peaks.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper presents a hybrid metasurface made of a gold film perforated with subwavelength apertures that are partially filled with annular vanadium dioxide and gold disks. Thermally driving VO2 through its insulator-to-metal transition changes the effective aperture area and the resonant modes inside each hole. One design moves the transmission peak from 1.02 THz to 0.82 THz while the other moves it from 0.71 THz to 0.77 THz. Transmission amplitude and frequency can also be tuned by stopping the transition partway. This provides a compact, non-mechanical route to adjustable terahertz components.

Core claim

A hybrid metasurface composed of an array of subwavelength apertures in gold film, each containing annular VO2 and gold disks, achieves reconfigurable extraordinary terahertz transmission; switching VO2 between insulator and metallic phases redshifts the peak from 1.02 to 0.82 THz in one layout or blueshifts it from 0.71 to 0.77 THz in the other, while partial phase transitions further modulate amplitude and resonance frequency.

What carries the argument

Annular VO2-gold disk inserts inside each aperture that alter the effective open area and the supported electromagnetic modes when VO2 changes conductivity.

If this is right

Temperature-controlled terahertz modulators become possible without mechanical parts.
Reconfigurable filters can be realized by choosing the annular geometry to set redshift or blueshift direction.
Partial heating of VO2 allows continuous tuning of both resonance frequency and transmitted power.
The same aperture platform can serve as a building block for dynamic terahertz devices.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

The approach could be adapted to other phase-change materials to reach different frequency ranges.
Electrical microheaters patterned beneath the apertures would enable faster, addressable switching.
Arrays with mixed VO2 geometries on one chip could produce spatially varying or multi-band responses.

Load-bearing premise

Numerical simulations correctly capture the real dielectric function and conductivity jump of VO2 across its phase transition, and the annular geometry can be made without large fabrication errors.

What would settle it

Fabricate the structures and record terahertz transmission spectra at room temperature and at 80 °C; the measured peak frequencies and their shifts must match the simulated values of 1.02-to-0.82 THz or 0.71-to-0.77 THz.

Figures

Figures reproduced from arXiv: 2605.05918 by Hadi Soofi, Sanam Saeidnahaei S, S. Hadi Badri.

**Figure 1.** Figure 1: a) The structure of the tunable metasurface with transmission resonances. b) The top view of the unit cell. The view at source ↗

**Figure 2.** Figure 2: The transmission spectra of the metasurface for two phases of VO view at source ↗

**Figure 4.** Figure 4: Scattering cross-sections for a) the insulator and b) the metallic phases associated with the electric dipole (p view at source ↗

**Figure 5.** Figure 5: Transmission resonance vs. the gold disk’s radius, with all the other geometrical parameters set to view at source ↗

**Figure 7.** Figure 7: Transmission resonance vs. a) the hole radius while view at source ↗

**Figure 8.** Figure 8: Transmission resonance vs. the VO2 conductivity. As the conductivity gradually increases, the transmission resonance at 1.02 THz blueshifts and vanishes while another transmission resonance appears at 0.82 THz. 3. Designing a blueshifting metasurface with EOT In this section, we design a metasurface with a transmission resonance that blueshifts upon phase transition from the insulator to the metallic phase… view at source ↗

**Figure 9.** Figure 9: Top view of the unit cell of the second structure. In this structure, upon phase-transition from the insulator to the view at source ↗

**Figure 10.** Figure 10: The transmission spectra of the second proposed metasurface for the two phases of VO view at source ↗

read the original abstract

We numerically demonstrate a reconfigurable extraordinary terahertz transmission based on a phase-change material of vanadium dioxide (VO2). The proposed hybrid metasurface is composed of an array of subwavelength apertures perforated on a gold film. The holes are partially filled with annular VO2 and gold disks to control the effective aperture area and the modes inside the aperture. Switching between the insulator and the metallic phase of VO2 provides a convenient way to shift the transmission window. We present two designs offering redshift or blueshift of the extraordinary terahertz transmission. Upon phase transition from the insulator to the metallic phase, in the first design, the transmission peak redshifts from 1.02 to 0.82 THz while in the second design the transmission peak blueshifts from 0.71 to 0.77 THz. Furthermore, the transmission level and resonance frequency can be modulated by controlling the partial phase transition of the VO2. The potential applications for the proposed structures are terahertz modulators and reconfigurable filters.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

Two specific numerical designs using annular VO2 in gold apertures achieve modest redshift or blueshift of THz peaks on phase change, but the shifts rest on unstated permittivity values and transition modeling.

read the letter

The core result is two hybrid metasurface designs where partial annular VO2 plus gold disks inside subwavelength apertures let the transmission peak move from 1.02 to 0.82 THz in one case and from 0.71 to 0.77 THz in the other when VO2 switches from insulator to metal. Partial transitions are also said to allow further tuning of both frequency and amplitude. That is the concrete, usable output the paper delivers.

Referee Report

2 major / 2 minor

Summary. The manuscript numerically demonstrates thermally reconfigurable extraordinary terahertz transmission in a hybrid metasurface consisting of an array of subwavelength apertures in a gold film, with the apertures partially filled by annular VO2 regions and central gold disks. Two designs are presented that exploit the insulator-to-metal transition of VO2 to shift the transmission resonance: one redshifts the peak from 1.02 THz to 0.82 THz, while the other blueshifts it from 0.71 THz to 0.77 THz. The work further shows that partial phase transitions in VO2 allow continuous modulation of both transmission amplitude and resonance frequency, with suggested applications in THz modulators and reconfigurable filters.

Significance. If the reported frequency shifts and modulation behavior are confirmed, the designs provide a compact, thermally actuated route to dynamic THz filtering and modulation without external bias fields. The dual red/blue-shift options and partial-transition tunability increase practical utility for reconfigurable THz systems. The numerical approach is standard for metasurface design, but the absence of material-parameter disclosure and convergence checks limits immediate adoption or extension by the community.

major comments (2)

[Numerical methods / material modeling] Numerical methods / material modeling section: The complex permittivity (or conductivity) spectra assigned to VO2 in the insulating and metallic phases are not stated, nor is the effective-medium approximation used for intermediate (partial-transition) states. The central claims of specific shifts (1.02→0.82 THz and 0.71→0.77 THz) rest directly on these values; without them the quantitative results cannot be reproduced or benchmarked against measured VO2 data.
[Results] Results section (transmission spectra): No mesh-convergence study, boundary-condition verification, or comparison against analytic limits for the annular aperture geometry is provided. At THz frequencies where skin depth and subwavelength effects are pronounced, this omission leaves open the possibility that the reported resonance positions contain numerical artifacts.

minor comments (2)

[Figures] Figure captions should explicitly state the VO2 fill fraction and conductivity value used for each partial-transition curve to aid interpretation.
[Discussion] The manuscript would benefit from a brief discussion of fabrication tolerances for the annular VO2/gold geometry, even if only qualitative.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments, which have helped us improve the reproducibility of the numerical results in our manuscript. We address each major comment below and have revised the manuscript to incorporate the requested details on material parameters and numerical validation.

read point-by-point responses

Referee: Numerical methods / material modeling section: The complex permittivity (or conductivity) spectra assigned to VO2 in the insulating and metallic phases are not stated, nor is the effective-medium approximation used for intermediate (partial-transition) states. The central claims of specific shifts (1.02→0.82 THz and 0.71→0.77 THz) rest directly on these values; without them the quantitative results cannot be reproduced or benchmarked against measured VO2 data.

Authors: We agree that explicit material parameters are required for reproducibility. In the revised manuscript, we have added a dedicated subsection in the Methods section that specifies the complex permittivity spectra of VO2 for both the insulating and metallic phases, drawn from standard literature references. For intermediate states during partial phase transitions, we now explicitly describe the use of Bruggeman's effective-medium approximation, including the metallic filling factor as the control parameter and the corresponding formulas. These additions allow direct reproduction of the reported resonance shifts. revision: yes
Referee: Results section (transmission spectra): No mesh-convergence study, boundary-condition verification, or comparison against analytic limits for the annular aperture geometry is provided. At THz frequencies where skin depth and subwavelength effects are pronounced, this omission leaves open the possibility that the reported resonance positions contain numerical artifacts.

Authors: We acknowledge the importance of demonstrating numerical accuracy. In the revised manuscript and accompanying Supplementary Information, we have included a mesh-convergence study showing that the resonance frequencies stabilize to within 1% for the discretization levels employed. Boundary conditions are now detailed as periodic in the transverse plane and perfectly matched layers along the propagation direction. We have also added a comparison of the simulated transmission spectra for reference aperture geometries against analytical predictions for extraordinary transmission through subwavelength holes, confirming agreement within acceptable tolerances and ruling out significant numerical artifacts. revision: yes

Circularity Check

0 steps flagged

No circularity: results are direct outputs of standard EM simulation

full rationale

The paper reports numerical results from electromagnetic simulation of a metasurface with VO2 in two phases. Transmission peaks (1.02→0.82 THz redshift; 0.71→0.77 THz blueshift) are computed outputs under modeled material properties and geometry. No equations, parameters, or claims reduce by construction to fitted inputs or self-citations. The derivation chain consists of standard Maxwell solvers applied to a physical structure; no self-definitional, fitted-prediction, or uniqueness-imported steps exist. This is the expected non-finding for a pure simulation study.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The demonstration rests on standard electromagnetic modeling of known VO2 phase properties and metasurface physics; no new entities or free parameters are introduced beyond conventional simulation inputs.

axioms (2)

domain assumption Dielectric functions of VO2 in insulator and metallic phases are taken from established literature values.
Invoked to model the phase transition effect on transmission.
domain assumption Gold is treated as a perfect conductor at terahertz frequencies.
Standard approximation used in aperture modeling.

pith-pipeline@v0.9.0 · 5478 in / 1379 out tokens · 48384 ms · 2026-05-08T06:45:04.513076+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

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