  We demonstrate a gain-switched thulium fiber laser that can be continuously
tuned over 140 nm, while maintaining stable nanosecond single-pulse operation.
To the best of our knowledge, this system represents the broadest tuning range
for a gain-switched fiber laser. The system simplicity and wideband wavelength
tunability combined with the ability to control the temporal characteristics of
the gain-switched pulses mean this is a versatile source highly suited to a
wide range of applications in the eye-safe region of the infrared, including
spectroscopy, sensing and material processing, as well as being a practical
seed source for pumping nonlinear processes.
