Photonic Crystal Ring Resonators for Tailored Optical Microcombs

Nonlinear-wave mixing in optical microresonators offers a promising avenue for compact optical-frequency microcomb generation [1]. These microcombs have rapidly found applications across diverse fields, including optical frequency synthesis and high-capacity data communication systems. A fundamental characteristic of microcombs is their spectral profile, which is principally determined by the resonator’s dispersion. An illustrative example is the sech2 spectrum of dissipative Kerr solitons that emerges under anomalous group-velocity dispersion.

Concurrently, photonic crystal ring resonators (PhCR) have emerged as a flexible way of tailoring of optical microcavities [2]. These ring resonators introduce a corrugation to the inner wall of the waveguide, enabling precise and independent control of cavity mode resonance frequencies while preserving a high quality factor (Q). This innovative approach offers mode-by-mode frequency splitting capabilities, vastly expanding the design space for managing the nonlinear dynamics of optical states, such as Kerr solitons.

This presentation explores the advantages of this enhanced control, initially focusing on the control and generation of microcombs in the normal dispersion regime. I also demonstrate the creation of a ‘meta-dispersion’ resonator by selectively manipulating the resonance of multiple modes with a PhCR. The nonlinear modeling of these structures unveils new comb states and instabilities.
Furthermore, by embedding the governing equation of the system into a genetic algorithm, we efficiently pinpoint a dispersion profile that yields a microcomb closely aligned with a user-defined target spectrum [3].