Single-frequency Bismuth-doped fiber laser with quasi-continuous self-sweeping

Generation of regular pulses of linearly polarized radiation with periodic self-induced laser line sweeping by similar to 10 nm near central wavelength of similar to 1460 nm has been demonstrated for the first time in an all-fiber Bismuth laser without any tuning element. It has been shown that the radiation of each pulse is single-frequency, and the pulse-to-pulse frequency shift is as low as 1 MHz corresponding to one intermode interval in 100-m long laser cavity. The measured intra-pulse frequency chirp is below 1 MHz while the pulses are long (similar to 10 mu s) and overlapping. Thus the sweeping is nearly continuous in frequency and time domains. (C) 2015 Optical Society of America