  The Photon Detectors Topical Group has identified two areas where focused R&D
over the next decade could have a large impact in High Energy Physics
Experiments. These areas described here are characterized by the convergence of
a compelling scientific need and recent technological advances. Key messages:
  IF02-1 The development of detectors with the capability of counting single
photons from IR to UV has been a very active area in the last decade. We now
need to pursue R\&D to implement these in HEP experiments by making larger
arrays, improving their energy resolution, timing, dark counts rates and
extending their wavelength coverage.
  IF02-2 New photon detector developments are being considered for planned
future neutrino experiments going beyond the current technologies. Concept
demonstrations have been done, and we now need to move from a conceptual phase
to working detectors.
  The science for generation, detection and manipulation of light is extremely
fast moving and driven mainly from outside our field. The HEP community would
benefit from resources dedicated to the implementation of these advanced
photonic technologies in particle physics experiments.
