Alignment tolerances for plane-wave to single-mode fiber coupling and their mitigation by use of pigtailed collimators

Wallner, Oswald; Winzer, Peter J.; Leeb, Walter R.

doi:10.1364/ao.41.000637

Cited by 61 publications

(29 citation statements)

References 14 publications

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“…To compute the coupling ratio into the single-mode fibers, we assumed that the fiber coupler numerical aperture is optimized for the mode of the fibers. Following Wallner et al (2002), the fiber mode field radius ω 0 is then…”

Section: Fiber Injection Efficiencymentioning

confidence: 99%

Comparison of fringe-tracking algorithms for single-mode near-infrared long-baseline interferometers

Choquet

Perrin

et al. 2014

A&A

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To enable optical long baseline interferometry toward faint objects, long integrations are necessary despite atmospheric turbulence. Fringe trackers are needed to stabilize the fringes and thus increase the fringe visibility and phase signal-to-noise ratio (S/N), with efficient controllers robust to instrumental vibrations and to subsequent path fluctuations and flux drop-outs. We report on simulations, analysis, and comparison of the performances of a classical integrator controller and of a Kalman controller, both optimized to track fringes under realistic observing conditions for different source magnitudes, disturbance conditions, and sampling frequencies. The key parameters of our simulations (instrument photometric performance, detection noise, turbulence, and vibrations statistics) are based on typical observing conditions at the Very Large Telescope observatory and on the design of the GRAVITY instrument, a 4-telescope single-mode long-baseline interferometer in the near-infrared, next in line to be installed at VLT Interferometer. We find that both controller performances follow a two-regime law with the star magnitude, a constant disturbance limited regime, and a diverging regime limited by both the detector and photon-noise. Moreover, we find that the Kalman controller is optimal in the high and medium S/N regime owing to its predictive commands based on an accurate disturbance model. In the low S/N regime, the model is not accurate enough to be more robust than an integrator controller. Identifying the disturbances from high S/N measurements improves the Kalman performances in the case of strong optical path difference disturbances.

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Section: Fiber Injection Efficiencymentioning

confidence: 99%

Comparison of fringe-tracking algorithms for single-mode near-infrared long-baseline interferometers

Choquet

Perrin

et al. 2014

A&A

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“…For our Fizeau recombination in the near-infrared, we preferred to use single-mode optical fibers (Shaklan 1990;Coudé Du Foresto 1997;Wallner et al 2002) rather than bulk optics, as they provide a more flexible and compact solution for a beam combination. The spatial filtering properties of singlemode fibers are used to properly convert random atmospheric phase perturbations into photometric fluctuations.…”

Section: The Monomode Fiber Telescope Linkmentioning

confidence: 99%

Combining Coronagraphy With Interferometry as a Tool for Measuring Stellar Diameters

Riaud¹,

Hanot²

2010

ApJ

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The classical approach for determining stellar angular diameters is to use interferometry and to measure fringe visibilities. Indeed, in the case of a source having a diameter larger than typically λ/6B, B being the interferometer's baseline and λ the wavelength of observation, the fringe contrast decreases. Similarly, it is possible to perform angular diameter determinations by measuring the stellar leakage from a coronagraphic device or a nulling interferometer. However, all coronagraphic devices (including those using nulling interferometry) are very sensitive to pointing errors and to the size of the source, two factors with significant impact on the rejection efficiency. In this work, we present an innovative idea for measuring stellar diameter variations, combining coronagraphy together with interferometry. We demonstrate that, using coronagraphic nulling statistics, it is possible to measure such variations for angular diameters down to ≈λ/40B with 1σ error-bars as low as ≈λ/1500B. For that purpose, we use a coronagraphic implementation on a two-aperture interferometer, a configuration that significantly increases the precision of stellar diameter measurements. Such a design offers large possibilities regarding the stellar diameter measurement of Cepheids or Mira stars, at a 60-80 μas level. We report on a simulation of a measurement applied to a typical Cepheid case, using the VLTI-UT interferometer on Paranal.

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“…There are three position deviations considered in Fig. 3 [13,18], namely, (i) the off-axis deviations, which result from the misalignment between the optical axis of the fiber and that of the lens in the end face of the SMF and are described by Δx and Δy, respectively; (ii) the defocus deviation, which arises because the end face of the fiber is not located at the focal point of the lens and is denoted by Δz; (iii) the angle deviation, which arises from the angle tilt between the optical axis of the fiber and that of the lens. The Gauss function can be used to described the influence of three position deviations on the Gaussian mode field distribution of plane A back-propagated from plane B, and the coupling efficiency under the influences of the three position deviations can be analyzed and obtained [11].…”

Section: Influence Of the Position Deviation On Coupling Efficiencymentioning

confidence: 99%

A fiber coupling system based on the GRIN lens for use in all-fiber lidars

2012

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The all-fiber lidar shows exciting prospects in space-borne applications, but the coupling efficiency between the telescope and a single-mode fiber is an important problem in the lidar design. We employ the mode-matching theory to analyze theoretically the coupling efficiency. In practical coupling system design, three position deviations, which are the off-axis deviation, defocus deviation, and angle deviation, exert a substantial influence on the coupling efficiency and must be considered and discussed. Generally it is very difficult for a fiber coupling system based on a single lens to adjust the fiber position deviations and obtain the maximum coupling efficiency. Therefore, a coupling system, based on the GRIN lens combined with the lenses, is designed and employed to decrease the influence of these position deviations. We perform some numerical simulations to verify the feasibility of a coupling system based on the GRIN lens. Our results show that a coupling system based on the GRIN lens can overcome the off-axis deviation and defocus deviation and decrease the adjustment difficulty.

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Alignment tolerances for plane-wave to single-mode fiber coupling and their mitigation by use of pigtailed collimators

Cited by 61 publications

References 14 publications

Comparison of fringe-tracking algorithms for single-mode near-infrared long-baseline interferometers

Comparison of fringe-tracking algorithms for single-mode near-infrared long-baseline interferometers

Combining Coronagraphy With Interferometry as a Tool for Measuring Stellar Diameters

A fiber coupling system based on the GRIN lens for use in all-fiber lidars

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