Design, simulation, and fabrication of a 90° SOI optical hybrid based on the self-imaging principle
Bibliographic record
Abstract
This paper introduces a compact 90º optical hybrid, built on small size SOI waveguide technology .This optical hybrid is a critical component of a potentially low-cost coherent optical receiver design developed within the frame of our Optical Coherent Transmission for Access Network Extensions (OCTANE) project. In previous recent work, 90º optical hybrids were realized in SOI rib waveguide technology with 4 μm top silicon and a rib height of approximately 2 μm. In this paper, we introduce a compact 90º optical hybrid, built on small size SOI waveguide technology (1.5 μm SOI -based rib waveguide, with 0.8μm rib height). The proposed device consists of multimode interferometers (MMIs) connected in such a way that four different vector additions of a reference signal (local oscillator) and the signal to be detected are obtained. At the outputs, the hybrid provides four linear combination of the signal with the reference which differs by a relative phase shift of the reference of 90º. The four output signals are detected by a pair of balanced receivers to provide in-phase and quadrature (I&Q) channels. The phase differences arise naturally from the self imaging property of a MMI. The key elements of the 90º optical hybrid, including a 2×2 MMI, a 4×4 MMI, and polarization diversity configuration have been designed and simulated, using the numerical mode solving tool FIMMPROB. The 2×2 and 4×4 MMI had overall lengths of 701μm and 3712.5μm lengths respectively. Tapers are used to couple adiabatically single mode waveguides to the entrance and exit ports of the MMI to assure correct operation by avoiding coupling to the higher order transverse modes allowed at the entrance and exit ports of the MMI. The simulation results at 1550nm show polarization independence and phase errors between the ports of less than 0.03 degrees. Currently the design is in fabrication at the Canadian Photonics Fabrication Center with the support of CMC Microsystems and experimental results will be subject to a further report.
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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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".