Optical seminar | 09 October 2020

The simplest microring resonator scheme consists of an optical waveguide made of a Kerr medium that is looped back on itself guiding a single transverse mode. These devices have been extensively investigated because of their capability of generating cavity solitons based frequency combs, and therefore their potential for a variety of applications in optical communications, spectroscopy, and astronomy, not mentioning their potential as portable technology because of their reduced size. Cavity solitons commonly referred to as dissipative Kerr solitons (DKS) have been studied both in microresonator cavities operating in the anomalous dispersion regime, where the waveforms correspond to bright soliton pulses and in the normal dispersion regime with dark soliton-shaped waveforms. The frequency combs of dark solitons are fascinating because they display unusually high power-conversion efficiency compared with bright soliton pulses, but their excitation is more difficult than the former ones due to the lack of modulational instability in the effective blue-detuned pumping region. Here, we show that the interaction between two microresonators (Photonic molecule) offers another way for excitation of Kerr combs in the normal dispersion regime with a significantly broader area of experimental accessibility than that for the single-mode case.