  Recent work with laser-cooled molecules in attractive optical traps has shown
that the differential AC Stark shifts arising from the trap light itself can
become problematic, limiting collisional shielding efficiencies, rotational
coherence times, and laser-cooling temperatures. In this work, we explore
trapping and laser-cooling of CaF molecules in a ring-shaped repulsive optical
trap. The observed dependences of loss rates on temperature and barrier height
show characteristic behavior of repulsive traps and indicate strongly
suppressed average AC Stark shifts. Within the trap, we find that
$\Lambda$-enhanced gray molasses cooling is effective, producing similar
minimum temperatures as those obtained in free space. By combining in-trap
laser cooling with dynamical reshaping of the trap, we also present a method
that allows highly efficient and rapid transfer from molecular magneto-optical
traps into conventional attractive optical traps, which has been an outstanding
challenge for experiments to date. Notably, our method could allow nearly
lossless transfer over millisecond timescales.
