Brillouin spectrum narrowing in high extinction ratio nanosecond pulse from phase locked DFB lasers
Bibliographic record
Abstract
The Brillouin spectrum narrowing phenomenon for nanosecond pulses in Brillouin Optical Time Domain Analysis (BOTDA) sensor system is demonstrated with high extinction ratio (ER > 24 dB) nanosecond pulse over short fibre length (10 m). The line width of the Brillouin spectrum is ~52 MHz for 10 ns pulse by feedback phase locking of the pump and probe waves from: 1) DFB lasers (2 MHz bandwidth) and 2) fibre lasers (5 kHz bandwidth) at the Brillouin frequency. It is found that the coherent length (inverse of the Brillouin line width in the fibre) of the Brillouin scattering process is not determined by the laser bandwidth, rather by the enhanced phonon field generated from phase locked pump and probe lasers for nanosecond pulses. For the same bandwidth of the pump and probe lasers, the line width of the Brillouin spectrum with high extinction ratio nanosecond pulses under the phase locking of the pump and probe waves is much narrower than that from the frequency locking of the pump and probe waves at the Brillouin frequency.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".