Ultrafast tuning of two-dimensional planar photonic-crystal waveguides via free-carrier injection and the optical Kerr effect
Bibliographic record
Abstract
Femtosecond pump–probe reflectivity and second-harmonic spectroscopy experiments are used to investigate the optical tuning of leaky modes in a two-dimensional GaAs photonic-crystal waveguide. For above bandgap excitation with 270 fs, 800 nm pulses with a pump fluence of 100 μJ cm−2, a blueshift of 16±2 nm is measured for a 1900 nm leaky mode, as observed from the shift of the resonantly enhanced second-harmonic pulse. Theoretical calculations of carrier-induced changes in the refractive index from band filling, bandgap shrinkage, and Drude contributions are in good agreement with the results. Recovery occurs within 2 ps and is attributed to recombination via deep-centered defects. For below bandgap excitation with 166 fs, 1900 nm pulses with a fluence of 800 μJ cm−2, redshifts ≥1.5 nm of the 1360 nm leaky mode are induced via the optical Kerr effect during the early part of the pump pulse, but thereafter the mode is blueshifted, owing likely to free carriers injected into or from deep-centered defects.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".