  Astrophotonics lies at the interface of astronomy and photonics. This
burgeoning field -- now formally recognized by the optics community -- has
emerged over the past decade in response to the increasing demands of
astronomical instrumentation. Early successes include: (i) planar waveguides to
combine signals from widely spaced telescopes in stellar interferometry; (ii)
frequency combs for ultra-high precision spectroscopy to detect planets around
nearby stars; (iii) ultra-broadband fibre Bragg gratings to suppress unwanted
background; (iv) photonic lanterns that allow single-mode behaviour within a
multimode fibre; (v) planar waveguides to miniaturize astronomical
spectrographs; (vi) large mode area fibres to generate artificial stars in the
upper atmosphere for adaptive optics correction; (vii) liquid crystal polymers
in optical vortex coronographs and adaptive optics systems. Astrophotonics, a
field that has already created new photonic capabilities, is now extending its
reach down to the Rayleigh scattering limit at ultraviolet wavelengths, and out
to mid infrared wavelengths beyond 2500nm.
