  Since its emergence two decades ago, astrophotonics has found broad
application in scientific instruments at many institutions worldwide. The case
for astrophotonics becomes more compelling as telescopes push for AO-assisted,
diffraction-limited performance, a mode of observing that is central to the
next-generation of extremely large telescopes (ELTs). Even AO systems are
beginning to incorporate advanced photonic principles as the community pushes
for higher performance and more complex guide-star configurations. Photonic
instruments like Gravity on the Very Large Telescope achieve milliarcsec
resolution at 2000 nm which would be very difficult to achieve with
conventional optics. While space photonics is not reviewed here, we foresee
that remote sensing platforms will become a major beneficiary of astrophotonic
components in the years ahead. The field has given back with the development of
new technologies (e.g. photonic lantern, large area multi-core fibres) already
finding widespread use in other fields; Google Scholar lists more than 400
research papers making reference to this technology. This short review covers
representative key developments since the 2009 Focus issue on Astrophotonics.
