Contents 1. Introduction
Soliton microcombs have been observed and explored in Kerr microresonators during the past decade[1]. These mode-locked states have found fruitful applications in optical communication[2], spectroscopy[3], and laser ranging [4]. The optical spectra are often desired to be smooth and flat, in order to achieve uniform performance over different channels. The spectral envelope of a single soliton I(μ) normally follows a sech-squared function where the optical intensity decreases significantly at large mode numbers μ. Additionally, the mode interaction may introduce a local spectral perturbation that may increase the roughness of spectra.
