A novel laser obstacle warning and ranging system, for detecting hard-to-see long and thin obstacles in particular, comprises a fiber laser including a signal diode, a circulator, an erbium doped fiber, a wavelength division multiplexer, a narrow band reflector, a first fiber pump diode, an input combiner, an erbium-ytterbium co-doped fiber, a second fiber pump diode, an output combiner and a third fiber pump diode.