Control and enhancement of photo-induced refractive index modifications in fused silica
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Bibliographic record
Abstract
A thorough study of the femtosecond photo-inscription of optical waveguides in fused silica is presented. Quantitative phase microscopy was used to study the variation of the index contrast of the waveguides as a function of the writing conditions. It is revealed that waveguides based exclusively on Type I refractive index modifications are difficult to form for pulses longer than 300 fs. We show that this limitation can be circumvented by scanning the laser beam multiple times at low pulse energy. We also demonstrate that by equally multiplying the scan speed and the number of passes, the index contrast can be increased, which was not expected for the low-repetition-rate regime. Based on the nonlinear ionization memory, we propose an explanation for this phenomenon. For shorter pulses, multiple passes of the beam allowed for the formation of waveguides with an enhanced index contrast while preserving the morphology and uniformity of Type I modifications. Index contrasts up to 9 × 10 −3 in Heraeus F300 fused silica are reported. Using this method, waveguides that exhibits single mode operation at wavelengths of 405, 633, 980 and 1550 nm were successfully inscribed.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 it