Resonant excitation and all-optical switching of femtosecond soliton molecules


The emergence of confined structures and pattern formation are exceptional manifestations of nonlinear interactions found in a variety of physical, chemical and biological systems1. Facilitated by optical nonlinearities, solitons enable ultrashort temporal confinement of light and stable propagation despite the presence of dispersion. Such particle-like structures can assemble in stable arrangements, forming ‘soliton molecules’2,3. Recent work has revealed oscillatory internal motions of these bound states, akin to molecular vibrations4,5,6,7,8,9, raising the question of how far the ‘molecular’ analogy reaches, that is, whether further concepts from molecular spectroscopy apply and whether such intramolecular dynamics can be externally driven or manipulated. Here, we probe and control ultrashort bound states in an optical oscillator, using real-time spectral interferometry and time-dependent excitation. For a frequency-swept pump modulation, we analyse the nonlinear response and resolve anharmonicities in soliton interactions that lead to generation of overtones and sub-harmonics. Applying stronger stimuli, we demonstrate all-optical switching between states with different binding separations. These results could be applied to rapid pulse-pair generation and may stimulate the development of future instruments for ultrafast science.

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Fig. 1: Optical control scheme of soliton molecules.
Fig. 2: Driven soliton molecule.
Fig. 3: Numerical simulation of resonant behaviour.
Fig. 4: All-optical switching of soliton molecules.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The data processing and simulation codes that were used to generate the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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F.K. is part of the Max Planck School of Photonics supported by BMBF, Max Planck Society and Fraunhofer Society. We thank D. R. Solli for valuable discussions.

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All authors were closely involved in this study and contributed to the ideas, realization of the experiments, data analysis and interpretation, and the writing of the paper.

Correspondence to G. Herink.

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Kurtz, F., Ropers, C. & Herink, G. Resonant excitation and all-optical switching of femtosecond soliton molecules. Nat. Photonics 14, 9–13 (2020).

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