Heteronuclear multicolor soliton compounds induced by convex-concave phase in fiber lasers

Optical solitons emerging from fiber resonators generally possess similar properties that hinge on the system parameters. However, the generation of wavepackets composed of dissimilar solitons within the same laser cavity is still challenging in ultrafast lasers. Here, we report on heteronuclear multicolor soliton compounds composed of chirp-free conventional solitons and chirped dissipative solitons, by introducing convex-concave frequency phases in mode-locked fiber lasers. In spite of different lasing wavelengths, the dissipative solitons always overlap with the conventional solitons, giving birth to trains of modulated wavepackets. The resonant sidebands of two types of solitons follow from the same phase-matching principle dominated by the absolute value of cavity dispersion. Simulations fully substantiate the experimental results, confirming that the overlapping of two solitons is dominated by the co-action of saturable absorption and group-delay compensation. It is demonstrated that the phase-managed dissipative system is capable of supporting multicolor soliton compounds with distinct properties, offering an effective platform to reveal the interaction of dissimilar nonlinear wavepackets.