Perfect Soliton Crystal Linear-Wave Scattering Enables Spectrum Reconstruction

Frequency translation induced by the nonlinear interaction between a soliton microcomb and a linear wave has been proposed to create a comb spectrum with broad spanning. Bragg scattering triggers the coherent four-wave-mixing process to generate new frequency components. Utilizing the perfect soliton crystal (PSC) linear-wave scattering allows for the reconstruction of the comb spectrum, achieving spectral broadening and increasing the number of lines. By simultaneously separating two probe lasers on each edge of the PSC comb to stimulate the idler combs, the spectrum expands outward on both sides. Additionally, the study forms a pair of interleaved combs comprising PSC and idler combs with matching comb spacing to enhance the number of lines. The shape and efficiency of the idler comb are adjusted by varying the probe laser power and detuning. In comparison to the PSC comb with a 4% conversion efficiency, the idler comb exhibits a significantly higher conversion efficiency of nearly 50%. The findings demonstrate a straightforward method to reconstruct the PSC comb by introducing a probe laser to overcome the limitations imposed by microring properties.