Raman-assisted pure quartic platicons in microresonators

Pure quartic platicons (PQPs), relying on the balance of normal quartic dispersion and Kerr effect, possess superior energy-scaling laws than dissipative quadratic solitons. Their excitation and dynamics in microcavities are less uncovered as the lack of phase-matching conditions. Here, we numerically investigate PQP, and pure quartic breather (PQB) can be stably excited with strong and narrow Raman gain through Raman-assisted four-wave mixing (RFWM) in the presence of multiphoton absorption and free-carrier (FC) effects. The competition between Raman and Kerr effects induces the formation of asymmetric spectrums, temporal drift, and PQP with oscillatory peaks. Besides, the parameter spaces associated with the normalized turn-key detuning and FC lifetime for Raman quartic pulses and conventional quartic pulses are compared. The results demonstrate that the Raman effect significantly enriches the ranges of different states and broadens the parameters spaces for PQP formation. The successful PQP excitation in Si and Ge microresonators underscores the robustness of the proposed approach and unveils the dynamics of PQP in potential platforms.