Distributed Brillouin sensor system based on offset locking of two distributed feedback lasers
Bibliographic record
Abstract
An offset locking technique, which uses an external optical delay line to tune the distributed feedback (DFB) laser frequency and a proportional-integral-derivative (PID) controller to lock the tuned frequency, is proposed for the first time, to the best of our knowledge, in the distributed Brillouin sensor system. This method provides large tuning range (greater than 1 GHz), high tuning speed (less than 100 mus per frequency step), and frequency tuning is independent of the laser frequency and power. The two DFB lasers are phase locked at the Brillouin frequency using a hardware PID controller. Using this offset locking with optical delay line, we demonstrated a high signal-to-noise ratio of 32 dB, which allows 1 m spatial resolution and better than 0.6 MHz frequency measurement accuracy (equivalent to 0.5 degrees C temperature resolution or 8 microepsilon strain resolution) over kilometers sensing length. The bias of the electro-optic modulator is controlled by a lock-in amplifier to provide high temperature or strain measurement accuracy.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".