A 100-W 1178-nm continuous-wave single-frequency linearly polarized Raman fiber amplifier
Bibliographic record
Abstract
We report a 100-W continuous-wave (CW) 1178-nm narrowband polarization-maintaining (PM) Raman fiber amplifier (RFA) based on ESO’s patented RFA technology. A linearly-polarized 15-mW narrow-linewidth 1178-nm seed laser was amplified in a two-stage PM RFA counter-pumped by a PM 1120-nm fiber laser. Efficient suppression of stimulated Brillouin scattering (SBS) pushed the SBS threshold above 100 W. The Raman fiber types and lengths were chosen to maximize the Raman conversion efficiency in order to mitigate the thermal loads on critical optical components in the RFA. At 100 W of RFA output, which to the best of our knowledge is a record for such an RFA, the required 1120-nm pump laser power is only 180 W. Measurements of the linewidth of the amplified 1178-nm output at different power levels confirmed that the narrow linewidth of the 1178-nm seed laser is preserved even at 100 W of RFA output. The measured polarization extinction ratio (PER) at the 100-W level is > 24 dB, ensuring efficient second harmonic generation. Assuming a conservative conversion efficiency of ~ 80% by a resonant frequency doubler, narrow-linewidth CW guide star lasers with powers > 80 W at 589 nm can confidently be expected. The output spectrum measured at 100 W reveals that there is no risk of power migration from 1178 nm to the next Stokes order, which indicates that the RFA is still SBS-limited. With further optimization of the SBS suppression, it is expected that the RFA output power can be scaled beyond the current 100-W level.
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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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".