  Optical emission from rare-earth-doped fluoride fibers has thus far been
limited to less than 4 {\mu}m. We extend emission beyond this limit by
employing an indium fluoride (InF3) glass fiber as the host, which exhibits an
increased infrared transparency over commonly used zirconium fluoride (ZBLAN).
Near-infrared pumping of a dysprosium-doped InF3 fiber results in broad
emission centered around 4.3 {\mu}m, representing the longest emission yet
achieved from a fluoride fiber. The first laser emission in an InF3 fiber is
also demonstrated from the 3 {\mu}m dysprosium transition. Finally, a frequency
domain excited state lifetime measurement comparison between fluoride hosts
suggests that multiphonon effects are significantly reduced in indium fluoride
fiber, paving the way to more efficient, longer wavelength lasers compared to
ZBLAN fibers
