Effect of writing beam spatial coherence on fiber Bragg grating modulation contrast and thermal stability
Bibliographic record
Abstract
We present a method to fabricate fiber Bragg gratings with adjustable refractive index contrast by using the standard phase mask technique. A theoretical analysis of the diffracted field from the phase mask is performed by considering the effect of the spatial coherence of the incident UV beam. The numerical results show that the grating index contrast decreases as the separation between the fiber and the phase mask increases. Strong gratings with various index contrasts have been inscribed in hydrogen-loaded single mode fibers at different writing distances, and the measured index contrast values are in good agreement with the simulation results. Furthermore, thermal decay tests on the gratings demonstrate that the thermal stability of the grating reflectivity is improved for those gratings fabricated at larger separations between the fiber and the phase mask. These results suggest a one-step process to fabricate gratings with an enhanced thermal stability.
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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".