PRAXIS: an OH suppression optimised near infrared spectrograph

Ellis, S. C.; Bland-Hawthorn, Joss; Bauer, Svend‐Marian; Case, Scott W.; Fechner, Thomas; Giannone, Domenico; Haynes, Roger; Hernandez, Eloy; Horton, Anthony; Klauser, Urs; Lawrence, Jon; Leon-Saval, Sergio G.; Löhmannsröben, Hans‐Gerd; Min, Sung-Hwan; Pai, Naveen; Roth, Martin; Waller, Lew; Zhelem, Ross

doi:10.1117/12.2311898

Cited by 8 publications

(6 citation statements)

References 24 publications

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“…The photonic lantern (PL; [11]) provides a capable platform for the above applications; other notable applications include OH line suppression through fiber Bragg gratings [12,13], and spectroastrometry [14]. As seen in Figure 1, the PL is a tapered waveguide that gradually transitions from a few-mode optical fiber (FMF) geometry to multiple widely-spaced single-mode cores, similar to a multi-core fiber (MCF), which can then be fanned out to an array of single-mode fibers (SMFs).…”

Section: Taper Lengthmentioning

confidence: 99%

Focal-plane wavefront sensing with photonic lanterns: theoretical framework

Lin¹,

Fitzgerald²,

Guyon³

et al. 2022

J. Opt. Soc. Am. B

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The photonic lantern (PL) is a tapered waveguide that can efficiently couple light into multiple single-mode optical fibers. Such devices are currently being considered for a number of tasks, including the coupling of telescopes and high-resolution, fiber-fed spectrometers, coherent detection, nulling interferometry, and vortex-fiber nulling. In conjunction with these use cases, PLs can simultaneously perform low-order focal-plane wavefront sensing. In this work, we provide a mathematical framework for the analysis of a PL wavefront sensor (PLWFS), deriving linear and higher-order reconstruction models as well as metrics through which sensing performance—in both the linear and nonlinear regimes—can be quantified. This framework can be extended to account for additional optics such as beam-shaping optics and vortex masks, and can be generalized for other wavefront sensing architectures. Finally, we provide initial numerical verification of our mathematical models by simulating a six-port PLWFS. In a forthcoming companion paper (Lin and Fitzgerald), we provide a more comprehensive numerical characterization of few-port PLWFSs, and consider how the sensing properties of these devices can be controlled and optimized.

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Section: Taper Lengthmentioning

confidence: 99%

Focal-plane wavefront sensing with photonic lanterns: theoretical framework

Lin¹,

Fitzgerald²,

Guyon³

et al. 2022

J. Opt. Soc. Am. B

Self Cite

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“…Such devices are already in use with fiber Bragg gratings (e.g. GNOSIS [14], PRAXIS [15]) and are currently being considered for use in focal plane wavefront sensing [16,17]. Figure 2 shows how a PL might be used in the context of high-resolution spectrometry.…”

Section: Transition Zonementioning

confidence: 99%

“…We additionally consider the 19-port lantern because such devices are already in use (e.g. GNOSIS [30], PRAXIS [15]). Additionally, these port numbers were selected because they reflect how the number of guided modes increases as core diameter is scaled up and/or wavelength is scaled down.…”

Section: Tested Configurationsmentioning

confidence: 99%

Design considerations of photonic lanterns for diffraction-limited spectrometry

2021

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The coupling of large telescopes to astronomical instruments has historically been challenging due to the tension between instrument throughput and stability. Light from the telescope can either be injected wholesale into the instrument, maintaining high throughput at the cost of point-spread function (PSF) stability, or the time-varying components of the light can be filtered out with single-mode fibers (SMFs), maintaining instrument stability at the cost of light loss. Today, the field of astrophotonics provides a potential resolution to the throughput-stability tension in the form of the photonic lantern (PL): a tapered waveguide which can couple a timevarying and aberrated PSF into multiple diffraction-limited beams at an efficiency that greatly surpasses direct SMF injection. As a result, lantern-fed instruments retain the stability of SMF-fed instruments while increasing their throughput. To this end, we present a series of numerical simulations characterizing PL performance as a function of lantern geometry, wavelength, and wavefront error (WFE), aimed at guiding the design of future diffraction-limited spectrometers. These characterizations include a first look at the interaction between PLs and phase-induced amplitude apodization (PIAA) optics. We find that Gaussian-mapping beam-shaping optics can enhance coupling into 3-port lanterns but offer diminishing gains with larger lanterns. In theand -band (0.97-1.35 μm) region, with moderately high WFE (∼10% Strehl ratio), a 3-port lantern in conjunction with beam-shaping optics strikes a good balance between pixel count and throughput gains. If pixels are not a constraint, and the flux in each port will be dominated by photon noise, then larger port count lanterns will provide further coupling gains due to a greater resilience to tip-tilt errors. Finally, we show that lanterns can maintain high operating efficiencies over large wavelength bands where the number of guided modes at the lantern entrance drops, if care is taken to minimize the attenuation of weakly radiative input modes.

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“…Ultimately, GNOSIS successfully demonstrated that the OH lines could indeed be suppressed with a complex FBG but did not demonstrate the improvement in sensitivity expected by suppressing the OH lines, which was limited by an unoptimized spectrograph design. For this reason, a second generation spectrograph called PRAXIS was built and is currently under development [26].…”

Section: B Compact Spectral Filtersmentioning

confidence: 99%

Astronomical Applications of Multi-Core Fiber Technology

Jovanović

Harris

Cvetojevic

2020

IEEE J. Select. Topics Quantum Electron.

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Optical fibers have altered astronomical instrument design by allowing for a complex, often large instrument to be mounted in a remote and stable location with respect to the telescope. The fibers also enable the possibility to rearrange the signal from a focal plane to form a psuedo-slit at the entrance to a spectrograph, optimizing the detector usage and enabling the study of hundreds of thousands of stars or galaxies simultaneously. Multi-core fibers in particular offer several favorable properties with respect to traditional fibers: 1) the separation between single-mode cores is greatly reduced and highly regular with respect to free standing fibers, 2) they offer a monolithic package with multi-fiber capabilities and 3) they operate at the diffraction limit. These properties have enabled the realization of single component photonic lanterns, highly simplified fiber Bragg gratings, and advanced fiber mode scramblers. In addition, the precise grid of cores has enabled the design of efficient singlemode fiber integral field units for spectroscopy. In this paper, we provide an overview of the broad range of applications enabled by multi-core fiber technology in astronomy and outline future areas of development.

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PRAXIS: an OH suppression optimised near infrared spectrograph

Cited by 8 publications

References 24 publications

Focal-plane wavefront sensing with photonic lanterns: theoretical framework

Focal-plane wavefront sensing with photonic lanterns: theoretical framework

Design considerations of photonic lanterns for diffraction-limited spectrometry

Astronomical Applications of Multi-Core Fiber Technology

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