Impact of angular pump power distribution on double-clad fiber temperature and incidence on high-power fiber laser reliability
Bibliographic record
Abstract
Double-clad fibers (DCF) found in kilowatt-class fiber lasers typically have a second cladding made of fluoroacrylate. At high power, thermal damage or accelerated aging of this material becomes an issue. The operating temperature of the fluoroacrylate coating is found to be highly sensitive to the numerical aperture (NA) distribution of the pump light flowing through the fiber. Characterization of this effect with an optical loss measurement is impractical as this loss remains typically very low. Measurement of the coating temperature for a given input power and far-field distribution is much more sensitive. Furthermore, it directly gives the parameters that are key to the design of a high-power fiber laser. A system for the measurement of the thermal slope of DCF fibers and high-power fiber components has been built and tested. This system allows varying the input power and the source NA under high power with a unique splice to the device being tested. To achieve this, different types of fiber-coupled pump diodes are spliced to the inputs of a pump combiner. Fiber tapers are used to fine tune the sources’ NA. By turning on different diodes, the NA of the injected pump light can be varied. The thermal slope for a given NA can then be measured with a thermal camera and a power meter. Measurements show differing thermal slopes of DCF measured before and after a damp heat tests. These thermal slope variations are stronger when operating at a high numerical aperture.
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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) | 0.003 | 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".