Femtosecond writing of intra-phase-mask volume Bragg gratings
Bibliographic record
Abstract
In this Letter, we report the first, to the best of our knowledge, femtosecond inscription of volume Bragg gratings (VBGs) directly inside phase-mask substrates. This approach showcases enhanced robustness as both the interference pattern generated by the phase mask and the writing medium are inherently bonded together. The technique is employed with 266-nm femtosecond pulses loosely focused by a 400-mm focal length cylindrical mirror inside fused-silica and fused-quartz phase-mask samples. Such a long focal length reduces the aberrations induced by the refractive-index mismatch at the air/glass interface which allows to inscribe a refractive-index modulation simultaneously over a glass depth reaching 1.5 mm. A decreasing gradient of the modulation amplitude from 5.9 × 10 −4 at the surface to 1 × 10 −5 at a 1.5-mm depth is observed. This technique has therefore the potential of increasing significantly the inscription depth of femtosecond-written VBGs.
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How this classification was reachedexpand
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".