ИСТИНА

The advent of microresonator based Kerr combs opens a path to novel applications where traditional optical frequency combs requiring bulky apparatus cannot be used. In this case, frequency comb is formed spontaneously in optical ring-type or whispering-gallery microresonator in four-wave mixing cascaded processes. Though initial expectations were somewhat mitigated by an intrinsic chaotic character of first generation combs, it was shown than coherent mode-locked combs associated with solitons are still possible without significant additional efforts on different platforms. Recent theoretical and experimental results with soliton combs from the Russian Quantum Center are reported. Key advantages of microresonator-based frequency combs are their compact form factor, high power per comb line, and ability to access microwave repetition rates, relevant for many application including high capacity telecommunications or microwave photonics. It was revealed that coherent Kerr combs are possible not only for anomalous group velocity dispersion necessary for bright optical solitons but also in normal dispersion systems using the so-called “platicons” – solitonic like flat-topped waveforms. This opens the ability to generate coherent combs in the UV or mid-IR spectral range with the gain bandwidth limited only by the transparency window. Recently demonstrated microresonator-based dual frequency combs open the possibility to transfer optical spectral measurements to the radio-frequency domain. New experimental methods of Kerr soliton generation using modulated pump and cheap regular wide spectrum multifrequency diode laser self-injection-locked high-Q microresonator will be discussed. The work was supported by the Russian Science Foundation project #17-12-01413 and Russian Foundation for Basic Research Project #17-02-00522