Ultra-low-loss and broadband wavelength demultiplexer on LNOI for 780/1550 nm using SWG-assisted directional coupling
Bibliographic record
Abstract
The wavelength division demultiplexer (WDD) is an indispensable component for separating and routing photons to spatially distinct detection nodes in practical quantum key distribution (QKD) systems. In this work, we propose an ultra-low-loss and broadband WDD based on lithium niobate on insulator (LNOI), designed and optimized through comprehensive three-dimensional simulations, utilizing subwavelength grating (SWG)-assisted double directional coupling for the separation of 780 and 1550 nm wavelengths. The SWG waveguide enables both a compact footprint and low insertion loss (IL) over a broad wavelength range, making it well suited for QKD applications. The optimized device, with a total length of 45 µm, achieves ILs of 0.04 dB at 780 nm and 0.22 dB at 1550 nm, along with extinction ratios of 22 and 32 dB, respectively. The 0.5 dB bandwidth exceeds 140 nm for 1550 nm and 230 nm for 780 nm. Furthermore, the structure exhibits strong tolerance to fabrication-induced variations, supporting its suitability for robust and scalable photonic integration.
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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 | 0.000 | 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".