Influence of fabrication disorder on the optical properties of coupled-cavity photonic crystal waveguides
Bibliographic record
Abstract
Employing a tight-binding formalism and perturbation theory, we theoretically demonstrate how weak fabrication disorder due to surface roughness dramatically reduces the band-edge performance of coupled-cavity waveguides in semiconductor photonic crystal slabs. We find that surface roughness largely affects the band-edge performance through the introduction of random variations in the individual cavity frequencies, ${\ensuremath{\Omega}}_{0}$, rather than through variations in the tight-binding coupling coefficients, $\ensuremath{\kappa}$. Using model roughness parameters comparable to state-of-the-art structures, the standard deviation of ${\ensuremath{\Omega}}_{0}$ is estimated to be ${\ensuremath{\sigma}}_{{\ensuremath{\omega}}_{0}}\ensuremath{\gtrsim}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ }{\ensuremath{\Omega}}_{0}$. High-index-contrast fabrication imperfections are found to broaden the photon density of states at the band edge with a characteristic linewidth of ${\ensuremath{\gamma}}_{e}\ensuremath{\approx}{\ensuremath{\sigma}}_{{\ensuremath{\omega}}_{0}}^{4/3}/{(2\text{ }{\ensuremath{\Omega}}_{0}\ensuremath{\kappa})}^{1/3}$. This implies a minimal band-edge group velocity of around ${v}_{g}\ensuremath{\sim}c/120$, consistent with experiments. For applications toward modified spontaneous emission, we show that the characteristic linewidth ${\ensuremath{\gamma}}_{e}$ is, unfortunately, a factor of 5 greater than the largest band-edge coupling rate for which strong photon quantum dot band-edge interactions can occur. Although large Purcell factors can still be achieved in the presence of disorder, an embedded semiconductor quantum dot then couples to a lossy (disorder-induced) propagation mode, which may limit the potential applications in coherent quantum optics.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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 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".