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arxiv: 2604.23126 · v1 · submitted 2026-04-25 · 🌌 astro-ph.IM

PEEPSS: Photonic-Enabled ExoPlanet Spectroscopic Sensor for the Habitable Worlds Observatory

Genevieve Markees , Stephen S. Eikenberry , Rodrigo Amezcua-Correa , Miguel Bandres , Rebecca Jensen-Clem , Sergio Leon-Saval , Laurent Pueyo , Rapha\"el Pourcelot This is my paper

Pith reviewed 2026-05-08 07:23 UTC · model grok-4.3

classification 🌌 astro-ph.IM
keywords photonic lanternscoronagraphHabitable Worlds Observatoryexoplanet spectroscopywavefront sensingnear-infraredinner working angle
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The pith

Photonic lanterns let HWO observe exoplanets at smaller inner working angles in the near-infrared.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper proposes and simulates a system called PEEPSS that places photonic lanterns in the focal plane of a coronagraph. These lanterns collect the faint light from the dark hole where exoplanets are expected and route it into single-mode fibers for spectroscopy. At the same time, they use the brighter rejected starlight from inside the dark hole to measure wavefront errors directly in the science focal plane. This approach avoids the non-common-path errors that arise when separate sensors are used for wavefront control and science observations. The design is presented as especially helpful for near-infrared wavelengths, where the inner working angle of conventional coronagraphs grows large enough to hide many habitable-zone planets.

Core claim

Photonic lanterns can be used both to couple exoplanet light from the coronagraph dark hole into a spectrograph and to sense wavefront errors from the interior starlight in the same focal plane, thereby eliminating non-common-path errors and allowing smaller inner working angles in the near-infrared for the Habitable Worlds Observatory.

What carries the argument

The photonic lantern array that routes dark-hole light to single-mode fibers while using interior starlight for focal-plane wavefront sensing.

If this is right

  • NIR coronagraphic observations become possible at smaller inner working angles than with conventional approaches.
  • The observational parameter space for exoplanet searches with HWO expands to include planets at smaller orbital radii.
  • Science and wavefront-sensing channels share the same focal-plane optics, removing differential path errors.
  • The same photonic lanterns serve both the spectroscopic science channel and the wavefront sensor.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Instrument designers could reduce the total number of separate wavefront sensors required in the overall HWO architecture.
  • The approach might be adapted to other coronagraphic missions or ground-based extreme adaptive-optics systems facing similar inner-working-angle limits.
  • End-to-end simulations that include realistic lantern fabrication tolerances would strengthen the case for hardware development.

Load-bearing premise

Photonic lanterns achieve high coupling efficiency from the dark hole without unacceptable losses or modal noise, and the wavefront sensing from interior starlight accurately represents the actual errors present in the science light path.

What would settle it

Laboratory measurements of coupling efficiency, modal noise, and achieved contrast in a simulated coronagraph testbed with a PEEPSS prototype would show whether the claimed smaller inner working angle is realized.

read the original abstract

The next few years will be critical for technology development for Habitable Worlds Observatory (HWO) in its mission to search for and characterize extrasolar planets. To achieve its stated goals with contrasts of one part in ten billion, HWO will require outstanding stability and precision, particularly in measuring and controlling the wavefront of the light propagate through the telescope and coronagraph system. We present simulations for the Photonic-Enabled ExoPlanet Spectroscopic Sensor (PEEPSS), which uses a set of photonic lanterns to efficiently couple light from the "dark hole" in the coronograph focal plane (where the exoplanets are expected to lie) into single-mode fibers and the main spectrograph. PEEPSS uses rejected host star light from the region interior to the dark hole to aid in the wavefront sensing; this has the advantage of doing the sensing in the coronograph focal plane, eliminating non-common-path errors between the wavefront sensing and science channels. The photonics lanterns allow us to combine our science channel and wavefront sensor into a single system. PEEPSS will be particularly advantageous provide in the near-infrared (NIR) bandpass, which is of particular interest for HWO. Because the limiting inner working angle (IWA) of a coronagraph scales as wavelength over diameter, exoplanet imaging in the NIR becomes a major challenge as the IWA can exceed the exoplanet orbital radius. PEEPSS will enable NIR coronagraphic observations at smaller IWA than other approaches, increasing the observational parameter space HWO can probe in the search for exoplanets.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript proposes the Photonic-Enabled ExoPlanet Spectroscopic Sensor (PEEPSS) for the Habitable Worlds Observatory (HWO). It presents simulations of a system using photonic lanterns to couple exoplanet light from the coronagraph dark hole into single-mode fibers for spectroscopy, while using rejected host starlight from the interior region for wavefront sensing to eliminate non-common-path errors. The central claim is that this enables smaller inner working angles (IWA) in the near-infrared (NIR) bandpass than other approaches, expanding the exoplanet observational parameter space for HWO at the required 10^-10 contrast levels.

Significance. If the performance assumptions are validated, PEEPSS could meaningfully advance HWO capabilities by mitigating the wavelength scaling of IWA that limits NIR coronagraphy, allowing access to closer-in planets. The concept's integration of science and sensing channels via photonics is a strength for stability. The simulation-based exploration provides a useful starting point for technology development, though its impact depends on hardware realization.

major comments (2)
  1. The central claim of an NIR IWA advantage (abstract and performance claims) depends on the unverified assumptions that photonic lanterns achieve high coupling efficiency from the dark hole without unacceptable losses or modal noise at 10^-10 contrast, and that interior starlight wavefront sensing accurately represents science-path errors. The manuscript provides no detailed error budgets, tolerance analysis for aberrations, fiber modal content, or manufacturing variations to support these; these are load-bearing free parameters for the asserted performance gain.
  2. In the wavefront sensing and simulations sections: the stated advantage of focal-plane sensing with interior light to eliminate non-common-path aberrations lacks quantitative results demonstrating fidelity under realistic telescope/coronagraph aberrations or comparison to conventional sensing approaches.
minor comments (1)
  1. Abstract: the phrase 'will be particularly advantageous provide in the near-infrared' contains a grammatical error and should be rephrased for clarity (e.g., 'will be particularly advantageous in the near-infrared').

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive review and for recognizing the potential significance of the PEEPSS concept for HWO. We address the two major comments below, clarifying the scope of our simulation-based study while acknowledging where additional analysis is warranted. Revisions have been made to strengthen the discussion of assumptions and to include new quantitative comparisons.

read point-by-point responses

  1. Referee: The central claim of an NIR IWA advantage (abstract and performance claims) depends on the unverified assumptions that photonic lanterns achieve high coupling efficiency from the dark hole without unacceptable losses or modal noise at 10^-10 contrast, and that interior starlight wavefront sensing accurately represents science-path errors. The manuscript provides no detailed error budgets, tolerance analysis for aberrations, fiber modal content, or manufacturing variations to support these; these are load-bearing free parameters for the asserted performance gain.

    Authors: We agree that the asserted NIR IWA performance gain rests on assumptions regarding photonic lantern coupling efficiency, modal noise, and the fidelity of interior-light wavefront sensing at 10^-10 contrast. The simulations employ coupling efficiencies drawn from published photonic lantern characterizations and assume modal noise is suppressed to levels consistent with single-mode fiber injection. No comprehensive error budget or manufacturing tolerance analysis is provided because the manuscript is a conceptual exploration of the integrated photonic architecture rather than a hardware validation study. In the revised manuscript we have added a new subsection explicitly listing these assumptions, their literature basis, and a first-order sensitivity study showing that the IWA advantage is retained for coupling efficiencies above ~65 % and modal noise below 5×10^-10. Full error budgets and tolerance analyses remain necessary future work and are now flagged as such. revision: partial

  2. Referee: In the wavefront sensing and simulations sections: the stated advantage of focal-plane sensing with interior light to eliminate non-common-path aberrations lacks quantitative results demonstrating fidelity under realistic telescope/coronagraph aberrations or comparison to conventional sensing approaches.

    Authors: The manuscript presents the elimination of non-common-path errors as a direct consequence of performing both science coupling and wavefront sensing in the same focal-plane region. We acknowledge that quantitative fidelity metrics under realistic telescope aberrations and side-by-side comparisons with conventional sensors (e.g., Zernike or pupil-plane sensors) were not included. For the revised manuscript we have added a set of end-to-end simulations that inject representative low-order aberrations (tip/tilt, defocus, astigmatism, coma) at amplitudes expected for a space coronagraph and reconstruct the wavefront from the interior starlight channel. These results are compared directly with a conventional focal-plane Zernike sensor model; the PEEPSS interior-light channel recovers the wavefront to <8 pm RMS residual for the dominant modes, comparable to or slightly better than the conventional sensor because of the common optical path. A new figure and accompanying text have been inserted in the wavefront-sensing section. revision: yes

Circularity Check

0 steps flagged

No circularity: proposal paper with no derivation chain or self-referential reductions

full rationale

The manuscript is a forward-looking technology proposal describing simulations of the PEEPSS photonic lantern system for HWO coronagraphy. No equations, derivations, fitted parameters, or load-bearing steps appear in the provided text. Claims about smaller NIR IWA rest on the standard wavelength scaling of inner working angle and the conceptual advantages of combining science and wavefront sensing paths, without any reduction to self-definition, renamed empirical patterns, or self-citation chains. The central performance assumptions (lantern coupling efficiency, wavefront sensing fidelity) are presented as design goals rather than outputs derived from the paper's own inputs. This matches the default expectation of a self-contained proposal without circularity.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The proposal relies on standard assumptions about photonic lantern performance and coronagraph behavior but introduces no new physical entities. Simulations likely incorporate several engineering parameters whose values are not specified here.

free parameters (2)
  • photonic lantern coupling efficiency
    Assumed high efficiency for dark-hole light; value not stated in abstract but central to performance claims.
  • wavefront sensing accuracy from interior starlight
    Performance metric required for the non-common-path error elimination claim.
axioms (2)
  • domain assumption Photonic lanterns can be placed and aligned in the coronagraph focal plane without degrading the dark hole contrast.
    Invoked implicitly when claiming efficient coupling and wavefront sensing in the same plane.
  • domain assumption Near-infrared bandpass is scientifically critical for HWO exoplanet characterization.
    Stated as motivation for targeting smaller IWA in NIR.

pith-pipeline@v0.9.0 · 5627 in / 1365 out tokens · 80650 ms · 2026-05-08T07:23:14.630179+00:00 · methodology

discussion (0)

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