Nonlinearity in complex systems leads to pattern formation through fundamental interactions between components. With integrated photonics, precision control of nonlinearity explores novel patterns and propels applications. In particular, Kerr-nonlinear resonators support stationary states—including Turing patterns—composed of a few interfering waves, and localized solitons composed of waves across a broad spectrum. Although Turing patterns emerge from an unstable Kerr resonator with sufficiently intense excitation, Kerr solitons do not form spontaneously under constant excitation, making this useful state challenging to access. Here we explore an edgeless photonic crystal resonator (PhCR) that enables spontaneous soliton formation in place of Turing patterns. We design the PhCR nanopattern for single-azimuthal-mode engineering of a group-velocity-dispersion defect that balances Kerr-nonlinear frequency shifts in favour of the soliton state. Our experiments establish PhCR solitons as modelocked pulses through ultraprecise optical-frequency measurements. We show that nanophotonics expand the palette for nonlinear engineering, enabling new phenomena and light sources.

复杂系统中的非线性通过组件之间的基本相互作用导致模式形成。通过集成光子学，非线性的精确控制探索了新的模式并推动了应用。特别是，克尔非线性谐振器支持由几个干扰波组成的稳态（包括图灵模式）和由广谱波组成的局部孤子。尽管图灵模式来自具有足够强激发的不稳定克尔谐振器，但克尔孤子在恒定激发下不会自发形成，这使得这种有用的状态难以获得。在这里，我们探索了一种无边光子晶体谐振器 (PhCR)，它能够代替图灵图案形成自发孤子。我们设计了用于群速度色散缺陷的单方位角模式工程的 PhCR 纳米图案，该缺陷平衡了有利于孤子态的克尔非线性频移。我们的实验通过超精确的光频测量将 PhCR 孤子建立为锁模脉冲。我们展示了纳米光子学扩展了非线性工程的调色板，实现了新的现象和光源。