Coupling light into few-mode optical fibres I: The diffraction limit

Optics Express (Impact Factor: 3.49). 03/2007; 15(4):1443-53. DOI: 10.1364/OE.15.001443
Source: PubMed


Multimode fibres are widely used in astronomy because of the ease of coupling light into them at a telescope focus. The photonics industry has given rise to a broad range of products but these are almost exclusively restricted to single-mode fibres, although some can be adapted for use in fibres that allow several modes to propagate. Now that astronomical telescopes are moving toward diffraction-limited performance through the use of adaptive optics (AO), we address the problem of coupling light into a few-mode fibre (FMF). We find that fibres with as few as ~5 guided modes share important characterisitcs with multimode fibres, in particular high coupling efficiency.We anticipate that future astronomical instruments at an AO-corrected focus will be able to exploit a broad class of photonic devices.

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    • "In its current configuration the spectrograph has limited applications, due to the difficulty of coupling light from a telescope into a single-mode core [1]. However, there have been some interest in using single-mode and very few-mode fibers in telescopes with AO systems and extremely high resolution R~200000 have been demonstrated with this configuration [8]. "
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