Spontaneous microwave platicon frequency microcomb in dispersion-managed microresonators

TL;DR

This paper reports the first observation of mode-locked platicon frequency microcombs in dispersion-managed microresonators operating at microwave K-band, demonstrating stable pulse generation and control with potential for ultrafast applications.

Contribution

It introduces the experimental realization of mode-locked platicon microcombs in dispersion-managed microresonators, supported by nonlinear simulations and phase noise characterization.

Findings

Stable generation of various platicon bound states.

Switchable number of mode-locked pulses via cavity detuning.

Repetition rate phase noise comparable to electronic oscillators.

Abstract

Temporally stabilized optical pules, confined in microresonators driven by a continuous-wave laser, have attracted tremendous attention due to their fascinating features with many applications. Here we report the observations of mode-locked platicon frequency microcomb formation in normal dispersion dispersion-managed microresonators operating at microwave K-band repetition rate for the first time. Facilitated by the thermally controllable modulated background induced by avoided mode-crossings, various platicon bound state patterns with regular and irregular temporal separation are stably generated due to an additional balance between repulsive and attractive forces resulting from non-trivial interpulse and background electromagnetic field interactions. The number of mode-locked pulses can be switched by forward- and backward-cavity pump detuning and, with increasing pump power, result in stationary bound-state complexes. These experimental observations are in accordance with our nonlinear numerical simulations that includes avoided mode-crossing, anomalous fourth-order dispersion and quality-factor spectral filtering. The observed platicon mode-locked pulses have broad spectral profiles overlapping Kelly-sideband-like parametric oscillation. The single-sideband phase noise of microcomb repetition rate is characterized for the different mode-locked states, comparable with electronic microwave oscillators. The ability to achieve mode-locking in dispersion-managed microresonators provides a platform to reduce pulse timing jitter and enrich the exploration of ultrafast phenomena in microresonators.