Dysprosium-doped ZBLAN fiber laser tunable from 2.8 {\mu}m to 3.4 {\mu}m, pumped at 1.7 {\mu}m

We demonstrate a mid-infrared dysprosium-doped fluoride fiber laser with a continuously tunable output range of 573 nm, pumped by a 1.7 {\mu}m Raman fiber laser. To the best of our knowledge, this represents the largest tuning range achieved to date from any rare-earth-doped fiber laser and, critically, spans the 2.8-3.4 {\mu}m spectral region, which contains absorption resonances of many important functional groups and is uncovered by other rare-earth ions. Output powers up to 170 mW are achieved, with 21% slope efficiency. We also discuss the relative merits of the 1.7 {\mu}m pump scheme, including possible pump excited-state absorption.