Long-wavelength VCSELs for applications in absorption spectroscopy: tuning rates and modulation performances
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Bibliographic record
Abstract
We used direct absorption spectroscopy for characterization of long-wavelength VCSELs (VERTILAS, Germany). Gas mixture CO:CO<sub>2</sub>=1:1 (total pressure 0.1 - 0.5 bar) provided in the tuning ranges of lasers a multitude of absorption lines spaced by intervals from 1 to 60 GHz that allowed the absolute calibration of laser scans. We measured tuning rates of the VCSELs in 0-50 °C temperature interval in dependence on injection current and modulation frequency varied from 0 up to 6.5 mA and 500 kHz respectively. The continuous tuning range of the 1577.5-nm VCSEL with single-mode output of up to 1.5 mW was found to be of 9.61 nm (38.62 cm<sup>-1</sup>). The temperature tuning rates for all VCSELs under study were in the range between -0.4 and -0.5 cm<sup>-1</sup>/ °C. The current tuning rates, varied from laser to laser between -1.9 and -2.2 cm<sup>-1</sup>/mA at low injection currents and modulation frequencies, were found to be twice as big for all lasers at high injection currents and decreased by factor 2 and 5 at modulation frequencies of 300 and 500 kHz respectively. A phase shift between the amplitude and frequency modulations was measured by fine tuning VCSEL with a DC injection current to display the end of a laser scan in respect to a local maximum in laser power. The phase shift changed from 0 to -0.3 rad with modulation frequency raised from 500 Hz to 500 kHz. The results of phase shift measurements have been compared with those obtained recently for DFB lasers with different methods.
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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 | 0.001 |
| 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 it