Perfect soliton crystals on demand

TL;DR

This paper demonstrates the on-demand generation and control of perfect soliton crystals in a lithium niobate microresonator, enabling flexible tuning of soliton microcomb line spacing for advanced optical applications.

Contribution

It introduces a method for deterministic and repetitive creation of perfect soliton crystals, overcoming stochastic excitation challenges in microresonators.

Findings

Arbitrary dialing of comb line spacing from 1 to 11 times the free-spectral range

Deterministic and repetitive switching between different PSC states

Enhanced control over soliton pulse repetition rates

Abstract

Recent advance of soliton microcombs has shown great promise to revolutionize many important areas such as optical communication, spectroscopic sensing, optical clock, and frequency synthesis. A largely tunable comb line spacing is crucial for the practical application of soliton microcombs, which unfortunately is challenging to realize for an on-chip monolithic microresonator. The recently discovered perfect soliton crystal (PSC) offers a convenient route to tune the comb line spacing. However, excitation of a PSC is generally stochastic by its nature and accessing a certain PSC state requires delicate tuning procedure. Here we demonstrate the on-demand generation of PSCs in a lithium niobate microresonator. The unique device characteristics allow us to produce a variety of PCSs and to switch between different PSC states, deterministically and repetitively. We utilize the device to show arbitrary dialing of the comb line spacing from 1 to 11 times of the free-spectral range of the resonator. The demonstration of PCSs on demand may now open up a great avenue for flexibly controlling the repetition rate of soliton pulses, which would significantly enhance and extend the application potential of soliton microcombs for communication, signal processing, and sensing.