Demonstration of Type A volume Bragg gratings inscribed with a femtosecond Gaussian-Bessel laser beam
Bibliographic record
Abstract
To our knowledge, we report on the first demonstration of Type A VBGs inscribed in silver-containing phosphate glasses by femtosecond laser writing. The gratings are inscribed plane-by-plane by scanning the voxel of a 1030 nm Gaussian-Bessel inscription beam. This results in a refractive-index modification zone, induced by the appearance of silver clusters, extending over a much larger depth than those obtained with standard Gaussian beams. As a result, a high diffraction efficiency of 95% at 632.8 nm is demonstrated for a 2-µm period transmission grating with a 150-µm effective thickness indicating a strong refractive-index modulation of 1.78 × 10 −3 . Meanwhile, a refractive-index modulation of 1.37 × 10 −3 was observed at a wavelength of 1.55 µm. Thus, this work opens the avenue for highly effective femtosecond-written VBGs suitable for industrial applications.
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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".