  The burgeoning field of astrophotonics explores the interface between
astronomy and photonics. Important applications include photonic OH suppression
at near-infrared wavelengths, and integrated photonic spectroscopy. These new
photonic mechanisms are not well matched to conventional multi-mode fibres and
are best fed with single or few-mode fibres. We envisage the largest gains in
astrophotonics will come from instruments that operate with single or few-mode
fibres in the diffraction limited or near diffraction limited regimes. While
astronomical instruments have largely solved the problem of coupling light into
multi-mode fibres this is largely unexplored territory for few-mode and
single-mode fibres. Here we describe a project to explore this topic in detail,
and present initial results on coupling light into single and few-mode fibres
at the diffraction limit. We find that fibres with as few as ~5 guided modes
have qualitatively different behaviour to single-mode fibres and share a number
of the beneficial characteristics of multi-mode fibres.
