  The Deep Underground Neutrino Experiment (DUNE) will be a premier facility
for exploring long-standing questions about the boundaries of the standard
model. Acting in concert with the liquid argon time projection chambers
underpinning the far detector design, the DUNE photon detection system will
capture ultraviolet scintillation light in order to provide valuable timing
information for event reconstruction. To maximize the active area while
maintaining a small photocathode coverage, the experiment will utilize a design
based on plastic light guides coated with a wavelength-shifting compound, along
with silicon photomultipliers, to collect and record scintillation light from
liquid argon. This report presents recent preliminary performance measurements
of this baseline design and several alternative designs which promise
significant improvements in sensitivity to low-energy interactions.
