Terahertz Time-Domain Investigation of Axial Optical Activity from a Sub-wavelength Helix
Bibliographic record
Abstract
Chiral media are characterized by preferential interaction with either left- or right- circularly polarized radiation, whereupon an optically active medium and its enantiomorph possess rotary powers of opposing sign due to mirror handedness of their micro- or nano-structures. Here, we report on the first time-resolved investigations of few-cycle pulse propagation along the axis of a sub-wavelength size helix. Time-resolved measurements of the electric field pulse scattered from the helix enable temporal discriminations of transient scattering mechanisms within the helix. Our main finding is that polarization circularization associated with axial propagation through the helix is non-instantaneous, and requires several picoseconds to develop before reaching steady state values. Using a 3D FDTD model, we describe the field and Poynting vector dynamics within the helix leading to steady state polarization circularization. Our conclusions not only support the established picture that optical activity arises from multiple scattering within the helical structure, but also show that this operative mechanism requires a finite time to induce steady state polarization circularization.
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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".