Normal-Dispersion Passively Mode-Locked High-Concentration Ytterbium-Doped Bismuth-Based Fiber Laser

Abstract

We have developed a normal-dispersion passively mode-locked ytterbium-doped bismuth-based fiber (YDBF) laser with a 1 GHz repetition frequency at around 1062 nm wavelength using a short linear cavity design. We confirmed a pulse train at a high-repetition frequency of 1 GHz with a pulse repetition interval of 1 ns with pump power of 390 mW. Dispersion compensation optics are not needed in the cavity. After adding dispersion to obtained spectrum data as the phase term, we Fourier-transformed them to obtain a pulse waveform. For that waveform, we roughly estimated the full width at half maximum (FWHM) of the pulse broadened by the chirp effect caused by normal dispersion of YDBF. It was about 860 fs.