Enhanced frequency-doubled pulse generation pumped by fundamental soliton molecules

To the best of our knowledge, this is the first experimental demonstration of enhanced pulse frequency doubling efficiency pumped by fundamental soliton molecules (SMs). A 1.0-µm polarization-maintaining (PM) ytterbium-doped oscillator-compressor system is first constructed to output various mode-locked pulse patterns, i.e., single-pulse-type dissipative solitons (DSs), noise-like pulses (NLPs) and soliton molecules (SMs), at a fundamental repetition rate of 62.7 MHz, respectively, by managing the intracavity dispersion parameters. Then, these pulse patterns are used as pump seeds for exciting frequency-doubled pulse generation at a wavelength of 515 nm based on second harmonic generation (SHG) in a commercial periodically polarized LiNbO3 (PPLN) crystal. Among the abovementioned pulse pump schemes, the SHG conversion efficiency is increased by up to 29 % when fundamental SMs are used as pump seeds for frequency-doubled pulse generation compared with the use of a conventional single-pulse-type DS pump scheme. Our work provides a promising technique for enhancing frequency-doubled pulse generation, which contributes to an in-depth understanding of frequency-doubled pulse generation with a coherent multipulse pump scheme.