Spatially Filtered Feedback for Mode Control in Vertical-Cavity Surface-Emitting Lasers
Bibliographic record
Abstract
Transverse mode control of a vertical-cavity surface-emitting laser (VCSEL) is achieved by spatially filtered optical feedback. The spatial filter consisted of a pinhole, either 42 ¿m or 81 ¿m, in the 5.8 × magnified VCSEL image plane of a confocal lens arrangement. The pinhole was translated to map out the voltage drop across the VCSEL from spatially-selective feedback. For low injection currents, spatial filtered feedback enabled single fundamental mode operation due to higher-order mode suppression by appropriately locating the pinhole. For higher injection currents with five laser modes, spatial selection of feedback enabled control of the relative mode intensities and wavelengths. The maximum increase in mode intensity achieved was 1.8 × for the 4 ¿m pinhole and 2.4 × for the 81 ¿m pinhole. The maximum frequency shift achieved was - 2.7 GHz and - 7.1 GHz with the 42 ¿ and the 81 ¿m pinholes. The spatially selective optical feedback produced long-lived changes to the VCSEL even after the feedback was blocked-results for two separate trials where the recovery time was 38 minutes are presented (although results varied for different bias and feedback conditions).
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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) | 0.000 | 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 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".