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Home/Research Monitor
Issue 01 · September 2026

Terahertz Research Monitor

Every terahertz paper published in the window, read and indexed by hand. Search it, filter it, and follow the ten we think are worth building on.

412
papers indexed
218
free to read
176
direct PDF links
137
experimental
43
countries
The month at a glance
Papers by theme

Click a bar to filter the catalogue.

First author’s country

Top 12 of 43 · 314/412 resolved.

Ten worth building on

Ranked by how easily you could act on them: method fully specified, hardware you probably have, a clear next experiment.

1

Motion-tracking THz-TDS with time-programmable frequency combs

Japan · Experiment · Free · arXiv 2609.06024

Motion-Tracking Terahertz Time-Domain Spectroscopy Enabled by Time-Programmable Frequency Combs for Moving-Object Sensing

The measurement window is locked electronically onto a moving THz waveform at up to 308 Hz, so the sample no longer has to sit still. Everything needed is in a free preprint, and the hardware is a dual-comb THz-TDS — no new components, the novelty is in the phase-lock set-point control.

Next point it at a vibrating or conveyor-borne part and see whether thickness or moisture readings survive real production motion. A cheaper half-step is closed-loop feedback on a conventional delay stage.

Read the paper ↗PDF ↗
2

Physics-informed ML for THz-TDS quantification (coal–gangue)

China · Experiment · Free · Materials

Quantitative Prediction of Coal-Gangue Content Using THz-TDS and Physics-Informed Machine Learning

An effective-medium-theory-constrained neural network beats random forest, SVR, GPR and a plain ANN on the same data (R² 0.81). The whole feature set — time and frequency domain, refractive index, absorption, permittivity — and the cross-validation protocol are spelled out, and the paper is free with a PDF.

Next re-run the same pipeline on whatever mixture you already measure — polymers, powders, minerals. The transferable part is embedding a mixing law as a physics constraint, which is what keeps it honest on small datasets.

Read the paper ↗PDF ↗
3

Resonance-anchored surrogate for absorber design across topologies

China · Theory / simulation · Free · Nanomaterials

Resonance-Anchored Residual Surrogate for Spectral Prediction and Inverse Design of THz Metamaterial Absorbers

Most ML metasurface models must be retrained whenever the geometry family changes; this one predicts resonance frequency and the local spectrum around it across several topologies, and does forward prediction and inverse design in one model. Free, with enough architecture detail to reimplement.

Next train it on your own simulation library so design sweeps stop costing full-wave runs. Even a partial replication tells you whether the resonance-anchored representation generalises to your geometries.

Read the paper ↗
4

Self-referenced, multi-mode THz absorber sensing

Iran · Theory / simulation · Free · Discover Applied Sciences

Gap-engineered four-spiral terahertz metamaterial absorber for ratio-based self-referenced refractive-index sensing

Four spiral resonators with deliberately different gaps give four separated modes at 1.15–3.08 THz, used as reference, primary sensor, secondary sensor and monitor. Sensitivity 180 GHz/RIU. It is simulation-only on a PTFE/Au stack — no exotic materials — and diamond open access, so the full geometry is yours.

Next fabricate and test it, but the real prize is the ratio-based readout: referencing one mode against another cancels source drift and alignment error, which is the usual reason lab sensitivity does not survive outside the lab.

Read the paper ↗PDF ↗
5

SI-traceable field calibration of a commercial photomixer system

USA · Experiment · Free · arXiv 2609.11887

SI-Traceable Calibration and Performance Benchmarking of a Terahertz Photomixer Transmitter-Receiver System Using a Rydberg Atomic Sensor

A Rydberg atomic vapour sensor calibrates a commercial photomixer transmitter/receiver near 204 GHz via the Autler–Townes effect, tying field strength to atomic constants rather than a reference detector. Free preprint, and notably it benchmarks an off-the-shelf system rather than a bespoke one.

Next worth a conversation with a metrology institute — an SI-traceable field number on a datasheet is a claim competitors cannot easily match, and the method applies directly to photomixer sources you already sell or use.

Read the paper ↗PDF ↗
6

Review: THz-TDS coating-thickness measurement

China · Review · Free · J. Physics D: Applied Physics

Advances in coating thickness measurement using terahertz time-domain spectroscopy

Not a new result, but the most useful map in the batch: time-of-flight, model-based inversion and machine-learning methods compared, each with its valid range, assumptions, failure modes and representative accuracy. Free PDF from IOP.

Next use it as a gap list. The authors are explicit about where each method breaks down on multi-layer ultra-thin stacks — those breakdown points are where a differentiated product or a follow-up paper sits.

Read the paper ↗PDF ↗
7

Boson-peak time-of-flight fingerprinting of glasses

Japan · Experiment · Free · Materials

Time-of-Flight Detection of Boson Peak in Volcanic Glass

A plain THz-TDS time-of-flight measurement locates the boson peak in volcanic obsidian at 1.07 THz versus 1.2 THz for silica, and links the shift and the IR coupling coefficient to metal-ion modification of the SiO₄ network. No special equipment, free paper.

Next run a sample series of your own glasses. If peak position tracks composition the way this suggests, you have a cheap, non-destructive compositional fingerprint — an easy paper and a plausible QC niche.

Read the paper ↗
8

Deconvolution beating the THz-TDS thin-layer resolution limit

South Korea · Theory + experiment · Subscription · Sensors and Actuators A: Physical

Optimized regularization and deconvolution technique for overcoming resolution limits in THz-TDS applied to ceramic-coated battery separators

Optimised regularization plus deconvolution resolves ceramic coatings on battery separators below the usual pulse-width limit. It is pure post-processing, so it can be tested on waveforms you have already recorded — no hardware change at all. The catch: subscription-only.

Next reprocess an archived dataset where layers were too thin to separate. If the gain reproduces, it upgrades every thin-layer measurement retroactively, and battery separators are a growing inspection market.

Read the paper ↗
9

Sub-ppm gas sensing with a chaotic multimode laser diode

Japan · Experiment · Subscription · ACS Applied Optical Materials

Sub-ppm Ammonia Sensing via Terahertz Phase Modulation in Porous Glass with a Chaotic Laser Diode

Ammonia down to 0.2 ppm using THz phase modulation, with porous glass in the cell to increase molecule–surface interaction and a cheap chaotic multimode laser diode instead of a femtosecond source. Response follows a Langmuir adsorption model. Subscription, but the hardware bill is the lowest in this list.

Next swap the analyte and the porous host. The concept — cheap source plus adsorption-enhanced cell — is the most plausible route in this batch to a genuinely low-cost THz gas instrument.

Read the paper ↗
10

Passive wavelength-addressed 2D beam steering (diffractive network)

USA · Theory / simulation · Free · Advanced Optical Materials

Wavelength-Multiplexed 2D Beam Steering via a Passive Diffractive Network

Cascaded diffractive layers, jointly designed by deep learning, map 625 wavelength channels onto a 25×25 grid of output angles with no moving parts and no phase shifters. Demonstrated at 400–750 nm by Ozcan's group — whose diffractive layers are normally 3D-printed at THz frequencies. Free PDF.

Next the obvious build is the THz version: scale the layer design, print it, and use frequency as the steering key. That sidesteps the tunable-material problem that makes most THz beam steering slow or lossy.

Read the paper ↗PDF ↗
The Upside-Down Index

Research Monitor Scoring Standard v1.0 — prestige rankings reward what money buys; this one scores the opposite, and prints its formula.

+3 free from day one · +3→0 as the author list grows from one to twelve-plus · +3→0 as the venue gets more cited · +2 for avoiding the month’s fashionable keywords · +1 if the first author is outside the five dominant countries · −0.5 per promotional adjective. Maximum 12.

Theory and simulation

  1. 11.5UWB reflective linear-to-circular polarization converter2 authors, Iran, free the day it was posted · PDF ↗
  2. 11Interband absorption in semiconductor superlattices under crossed fields4 authors, Azerbaijan, diamond OA, journal almost nobody outside Russia reads · PDF ↗
  3. 10.5Theoretical studies on electron-beam-driven compact THz sources1 author, India, posted openly with no journal at all · doi:10.13140/rg.2.2.31616.60166
  4. 10.5Interfacial orbital torques excite nanoscale terahertz magnons3 authors, Germany, preprint · PDF ↗
  5. 10.5Safety-gated multi-band 6G V2X for cooperative autonomous vehicles1 author, Iraq, hybrid OA · doi:10.61856/f3dbqm84
  6. 10Triple-Debye modelling and FDTD for THz breast-cancer reflection2 authors, Iran, preprint · PDF ↗
  7. 10Beam squint and bandwidth limits in RIS-assisted THz links4 authors, China, preprint · PDF ↗
  8. 10Asymmetric waveguide photodiode with low optical back-reflection4 authors, China, preprint · PDF ↗

Experiment and instruments

  1. 11Polarization-resolved single-pixel THz imaging (PhD thesis)1 author, Canada, institutional repository · doi:10.14288/1.0455838
  2. 11Tera-EXPOSE: building a THz-pump / photoemission-probe station (project report)1 author, Germany, written in German, free · doi:10.34657/40975
  3. 11SiC D-band waveguide components for low loss at high power (PhD thesis)1 author, USA, university repository · doi:10.7274/33293103.v1
  4. 10.5Cryogenic platform for RF circuits and superconducting sensors (PhD thesis)1 author, Germany, repository · doi:10.24355/dbbs.084-202608191059-0
  5. 10THz optoelectronic properties of micro- and nano-grain diamond films4 authors, China, diamond OA, published in Chinese · PDF ↗
  6. 10Motion-tracking THz-TDS with time-programmable frequency combs4 authors, Japan, preprint · PDF ↗
  7. 10Super-resolution THz imaging with a freeform Bessel lens and radiator array8 authors, Hong Kong, preprint · PDF ↗
  8. 9.5SI-traceable calibration of a commercial THz photomixer system4 authors, USA, preprint · PDF ↗

What the index punishes

  1. 0.5Broadband MnSb₂Te₄ photodetector from visible to terahertzACS Appl. Mater. Interfaces · 14 authors · paywalled · doi:10.1021/acsami.6c07068
  2. 1.5High-entropy strategy for absorbers from GHz to THzActa Physico-Chimica Sinica · 10 authors · paywalled · doi:10.1016/j.actphy.2026.100434
  3. 2Ultrafast pathways of photo-induced magnetic phase transition in FeRhSmall · 9 authors · paywalled · doi:10.1002/smll.75771
  4. 2.5Enhanced THz emission via the circular photogalvanic effectPhysical Review Letters · 23 authors · paywalled · doi:10.1103/zlmj-gpj9
  5. 3Dual-functional THz manipulation in EuBa₂Cu₃O₇ superconductorsAdvanced Science · 11 authors · free but glamorous · doi:10.1002/advs.77616
  6. 3.5Negative refraction of terahertz phononsPhysical Review Letters · 8 authors · paywalled · doi:10.1103/n9zv-9kc5

Read honestly, the index measures accessibility and independence, not quality: a 23-author Physical Review Letters paper may need 23 people and a synchrotron, and a lone thesis is not automatically right. Publishing the weights is the point — the usual rankings hide theirs.

Built at a user facility

LCLS X-ray free-electron laser, SLAC (XPP instrument)

Slow thermalization and long-lived coherence across acoustic phonon branches in BAs · PDF ↗

Optical-pump / hard-X-ray-probe scattering at 120 Hz with a Si(111) monochromator — a beamtime experiment, stated in the methods.

Synergetic Extreme Condition User Facility (SECUF), Beijing

Revealing hidden inversion symmetry breaking in ZrTe₅ via phonon-assisted heterodyne amplification · PDF ↗

Acknowledgement names SECUF explicitly: “this work was carried out at the Synergetic Extreme Condition User Facility”.

HFML-FELIX, Radboud University Nijmegen

Magnetization and spin dynamics across field-induced transitions in Cu₂(OH)₃Br · PDF ↗

High-field magnet laboratory combined with the FELIX free-electron laser; a co-author is based at the facility.

TELBE, accelerator-based THz source at HZDR Dresden

Tera-EXPOSE: a THz-pump / photoemission-probe station (project report) · doi:10.34657/40975

The whole project is the construction of a permanent user station at what the report calls a worldwide-unique accelerator-based THz source.

Submillimetre observatories (JCMT, SMA and partners)

First VLBI fringe detection at 690 GHz · PDF ↗

Telescope time on a multi-site array — the astronomy equivalent of beamtime, and the highest-frequency VLBI result so far.

Balloon-borne observatory instrumentation (Terahertz Intensity Mapper)

Effects of magnetic fields on kinetic inductance detector arrays · doi:10.1117/12.3104160

Not beamtime itself, but detector development for a shared facility instrument — included because it competes for the same money and people.

Free-electron-laser accelerator sources (theory for)

Coherent collective amplification of terahertz microbunching seeded by laser frequency beating · arXiv:2609.18725

Not beamtime itself: a nonlinear theory for controlling the electron-beam microstructure that accelerator-based THz FEL sources depend on.

High Magnetic Field Laboratory, Hefei

Selective control of THz magnon-light interactions via light polarization · PDF ↗

Inferred from the author affiliations rather than a methods statement - the second half of the month was screened by abstract, not full text. Confirmed by reading methods and acknowledgements of the open full texts; paywalled papers could not be checked, so this is a floor, not a census.

Eight other ways to read the month

The same papers, cut along lines that suggest where to go next.

Records of the month — numbers to beat

The specific figures a follow-up has to exceed.

  • 11 THz of continuous absorption bandwidth, from one VO₂ absorber · PDF ↗
  • First interferometric fringes at 690 GHz — VLBI pushed into the submillimetre · PDF ↗
  • 0.2 ppm ammonia, with a laser diode instead of a femtosecond source · doi:10.1021/acsaom.6c00488
  • One detector covering 5.5 µm to 6 mm — three orders of magnitude in wavelength · PDF ↗
  • 308 Hz waveform tracking, no delay stage sweeping · PDF ↗
  • Eight Boolean logic gates on a single passive metasurface · PDF ↗
  • 625 wavelength channels mapped onto a 25×25 grid of output angles · PDF ↗
  • Twenty decades of frequency in one viscoelastic model · PDF ↗

Boldest claims — someone should check these

High-impact assertions resting on a single paper. Replication here is cheap publicity.

  • THz waves change how psychedelics bind serotonin receptors · PDF ↗
  • THz spectra predict glioma recurrence and survival at patient level · PDF ↗
  • Near-unity chiral purity in generated THz radiation · PDF ↗
  • Negative refraction — of phonons, not photons · doi:10.1103/n9zv-9kc5
  • Inverse orbital Hall effect seen in GaN, no spin-orbit coupling needed · PDF ↗
  • ZrTe₅ is not centrosymmetric after all · PDF ↗

Designed, never built — waiting for someone with a cleanroom

Numerical studies with complete geometries published. First group to fabricate one owns the experimental paper.

Where everyone is — and where nobody is

Half the month is one topic. The singletons are the white space.

  • Crowded: 137 metasurface papers — graphene appears in 35, VO₂ in 26, absorbers in 32
  • Crowded: 6G / communications, 44 papers, mostly channel models and antennas
  • Alone: cryogenics for space-borne THz instruments — one paper all month · doi:10.1016/j.cryogenics.2026.104474
  • Alone: THz energy harvesting with graphene rectennas · PDF ↗
  • Alone: heritage science / manuscript conservation · PDF ↗
  • Alone: SI-traceable field metrology — the whole field's calibration rests on this one · PDF ↗

THz meets the unexpected

Application papers from outside the usual physics-and-comms axis. Cheap sample access, little competition.

No new hardware — run these on data you already have

Pure method and post-processing papers. Zero capital cost, fastest path to a result.

Five new PhDs entered the field this month

Theses defended in September — a hiring and collaboration radar, and each one is a free 100-page review of its niche.

Where THz work gets read for free — and where it does not

If reach matters as much as venue prestige, this is the month's map.

  • Open by default: Research Square (9 free), Physica Scripta (6), Nature Communications, Scientific Reports and Photonics (5 each), Nanomaterials and Optics Express (4 each)
  • Preprint-first: 9 papers appeared on Research Square, 40 on arXiv, all free the day they landed
  • Mostly paywalled: IEEE Transactions on Plasma Science (8 subscription), Optical and Quantum Electronics (6), Applied Optics (5), PCCP, Journal of Applied Physics and Journal of Lightwave Technology (4 each)
  • Overall: 218 of 412 free to read, 176 with a direct PDF link in this document
The full catalogue
412 / 412 papers

Compiled 2026-10-12. Bibliographic data from OpenAlex (CC0) and arXiv.