Mid-IR (L-band) electro-optic photonics for nulling interferometry
Bibliographic record
Abstract
This work aims to present a complex mid-infrared (L-band : 3.4μm - 4.1μm) astrophotonic chip made in Lithium Niobate (LiNbO3), an electro-optic crystal, using Titanium diffused waveguides. The L-band presents several key characteristics interesting in astrophysics, notably for imaging and characterise young exo-planetary systems, as well as exo-zodiacal disks. With the increasing interest in exo-planetary science, new instruments and projects are focusing in the mid infrared, such as METIS (ground-based), NOTT (ground based), or LIFE (space-based). Combining such projects with photonics and on-chip beam combination will allow for more compact instruments, easing their integration on ground or, even more so, space based projects, hence the interest for improving the performances of photonic building blocks used for astrophysics. Here, we are presenting building blocks such as Y-splitters, directional couplers, unbalanced beam splitters... that have been optimised for the L-band in Lithium Niobate. Although such blocks have already been developed in the mid-IR in this material, we are here using a different crystal orientation and newer design that are producing lower losses and birefringence. In particular, a 4-telescope mid-infrared combiner (linked to the NOTT project) was made in order to achieve nulling interferometry in the L-band. We show that we have relatively low loss waveguides, controlled photometric splitters (20/80 flux ratio), as well as functional couplers and beam splitting techniques. Furthermore, we will implement the electro-optic effect in this chip, in order to have internal modulation, and to be able to finely tune the fringes and improve the contrast, allowing for a step further into compact nulling interferometry.
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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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".