Governing limits of spatial resolution and spectral bandwidth for implementations of terahertz spectroscopy on the subwavelength scale
Bibliographic record
Abstract
In this work, we consider the governing limits of spatial resolution and spectral bandwidth in pursuing implementations of terahertz (THz) spectroscopy on the subwavelength scale. We discuss the need for effective focusing elements in driving sufficient levels of power from the (macroscopic) incident THz beam down to the (microscopic) focal spot. Such elements, when effective, enable large signal strengths and wide bandwidths, but this has proven to be challenging in contemporary implementations of near-field THz imaging and spectroscopy. To this end, we show theoretical and experimental results for focusing via parabolic mirrors, high-resolution lenses, and engineered dielectric spheres, with the latter yielding THz microjets with especially intense and small focal spots. We then discuss the need for near-field spatial constriction, to drive the spatial resolution down to an even smaller scale, and show that this constriction can lead to dispersive (i.e., frequency-dependent) characteristics. In this work, we demonstrate spatial constriction via simple circular apertures, which function as high-pass filters. Ultimately, our theoretical and experimental results reveal that implementations of THz spectroscopy on the subwavelength scale are governed by a spatial-spectral product—whereby reductions in the aperture's diameter (to improve the spatial resolution) raise the aperture's cutoff frequency (at the expense of spectral bandwidth).
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".