Self-Starting Soliton–Comb Regimes in χ(2) Microresonators

The discovery of stable and broad frequency combs in monochromatically pumped high-Q optical Kerr microresonators caused by the generation temporal solitons can be regarded as one major breakthroughs nonlinear optics during last two decades. transfer soliton–comb concept to χ(2) promises lowering pump power, new operation regimes, entering spectral ranges; scientifically, it is a big challenge. Here we represent an overview accessible regimes discovered several years. main stress made on lithium niobate-based resonators. This pretends rather simple, complete, comprehensive: incorporates factors affecting generation, such choice pumping scheme (pumping first or second harmonic), phase matching (natural artificial), effects walk off dispersion coefficients, also influence detunings Q-factors. Most are self-starting—they accessed from noise upon not very abrupt increase power. scenarios universal—they realized only under proper combinations above-mentioned factors. We indicate what kind restrictions experimental conditions have imposed obtain generation.