High-efficiency dissipative Kerr solitons in microresonators
Doktorsavhandling, 2022

The microresonator comb (microcomb) is a laser source that generates equally spaced coherent lines in the spectral domain. Having a chip-scale size and the potential of being low cost, it has attracted attention in multiple applications. Demonstrations have included high-speed optical communications, light detection and ranging, calibrating spectrographs for exoplanet detection and, optical clocks. These experiments typically rely on the generation of a dissipative Kerr soliton (DKS) --- a temporal waveform that circulates the microresonator without changing shape. However, these DKS states have thus far been limited in certain technical aspects, such as energy efficiency, which are essential for realizing commercial microcomb solutions.

This thesis studies the dynamics of DKSs in microresonators aiming at developing a reliable and high-performing microcomb source. The investigation will cover DKSs found both in the normal and anomalous dispersion regime of silicon nitride microresonators. The performance of microcombs in terms of line power is numerically explored in single-cavity arrangements for telecommunication purposes. DKSs generated in linearly coupled microcavities are investigated, revealing exotic dynamics and improved performance in terms of power efficiency and DKS initiation. These studies facilitate reliable energy-efficient microcombs, bringing the technology a step closer to commercial use.


nonlinear optics

dissipative solitons

optical frequency combs

dissipative Kerr solitons


Room A423 (Kollektorn) at the Department of Microtechnology and Nanoscience (MC2), Kemivägen 9, Göteborg
Opponent: Prof. Alessia Pasquazi, School of Mathematical and Physical Sciences, University of Sussex, UK


Òskar Bjarki Helgason

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Superchannel engineering of microcombs for optical communications

Journal of the Optical Society of America B: Optical Physics,; Vol. 36(2019)p. 2013-2022

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Dissipative solitons in photonic molecules

Nature Photonics,; Vol. 15(2021)p. 305-310

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Bidirectional initiation of dissipative solitons in photonic molecules

2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021,; Vol. June 2021(2021)

Paper i proceeding

Ó. B. Helgason, M. Girardi, Z. Ye, F. Lei, J. Schröder and V. Torres-Company - Power efficient soliton microcombs

While a typical laser generates a single frequency (color) of light, the optical frequency comb generates multiple equally spaced frequencies. These equally spaced frequencies can be fixed in place with extremely high precision, such that they form a ‘ruler’ to measure the location and distances between other optical frequencies. This ‘ruler’ can give us more precise timekeeping with optical clocks, provide better sensitivity for the detection of exoplanets and help us detect chemicals.

The topic of this thesis is the microresonator frequency comb – a chip-scale version of the optical frequency comb. This miniature comb is enabled by optical pulses called dissipative Kerr solitons, which circulate the microresonator. Miniaturization could bring the frequency combs into new applications, such as object detection for autonomous vehicles and as a laser source for optical fiber communication. However, to become a competing solution in these applications, the microresonator combs still have some challenges to overcome, such as limited power efficiency. The publications in this thesis study the physics of dissipative Kerr solitons with the overarching goal of reliably achieving high-efficiency microresonator combs.


Informations- och kommunikationsteknik

Nanovetenskap och nanoteknik (SO 2010-2017, EI 2018-)


C3SE (Chalmers Centre for Computational Science and Engineering)



Atom- och molekylfysik och optik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5113



Room A423 (Kollektorn) at the Department of Microtechnology and Nanoscience (MC2), Kemivägen 9, Göteborg


Opponent: Prof. Alessia Pasquazi, School of Mathematical and Physical Sciences, University of Sussex, UK

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