The novel, extremely simple to assemble, design of a ~2.05 μm ytterbium–holmium co-doped all-fiber laser (YHDFL) oscillating in the gain-switching pulsed regime is reported. The YHDFL is pumped by a 1064 nm ytterbium doped fiber laser, while pulsing at ~2.05 μm, is accomplished using an acousto-optic modulator placed between the two lasers. At the optimal conditions, the YHDFL produces a train of very stable, single per modulation period, pulses, 1 μJ in energy and 1 μs in duration at a 3 dB level, at repetition rates of 50…60 kHz