# Fully Programmable Kerr Comb Mode-Locked Fiber Laser

Alexis Bougaud, Manal Arbati, Bruno Chaves, Antonio Cutrona, Arnaud

Mussot, Thomas Bunel, Alessia Pasquazi, Benjamin Wetzel

► To cite this version:

Alexis Bougaud, Manal Arbati, Bruno Chaves, Antonio Cutrona, Arnaud Mussot, et al. Fully Pro-grammable Kerr Comb Mode-Locked Fiber Laser. 2025 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), Jun 2025, Munich, Germany. pp.1-1, 10.1109/CLEO/Europe-EQEC65582.2025.11110400 . hal-05246837

HAL Id: hal-05246837

https://hal.science/hal-05246837v1

Submitted on 29 Sep 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Fully Programmable Kerr Comb Mode-Locked Fiber Laser

Alexis Bougaud¹, Manal Arbati¹, Bruno P. Chaves¹, Antonio Cutrona², Arnaud Mussot³, Thomas Bunel³, Alessia Pasquazi², Benjamin Wetzel¹.

1. XLIM Research Institute, CNRS UMR 7252, Université de Limoges, Limoges 87060, France

2. Emergent Photonics Research Centre, Dept. of Physics, Loughborough University, Loughborough, LE11 3TU, England, UK

3. Université de Lille, CNRS, UMR 8523—PhLAM—Physique des Lasers Atomes et Molécules, F-59000, Lille, France

Since their first conception in the 60's, mode-locked lasers (MLL) [1] have proved their efficiency to provide broad and coherent combs. Based on passive mode-locking strategies [2], ultrashort (sub-picosecond) and stable pulse trains are commonly realized nowadays [3]. Nevertheless, those broadband spectrums are generated at low repetition rate (sub GHz) which constitute the principal limitation of such approach. Over the last decades, Kerr comb regains attention towards providing broad spectrum and high repetition rate [4]. In particular, nested cavity architectures are of prime interest due to their efficiency and self-stabilization capabilities [5], yet the repetition rate of such lasers remains fixed by the dimensions of the resonator employed. Here, we propose a novel approach for fiber Kerr comb laser, including a Programmable Delay Line (PDL) based on photonic integrated circuits (Fig.1a) [6]. We numerically show that, by selecting the required harmonic of the MLL oscillation, this device allows for controlling the repetition rate of a Kerr comb generated within a nested cavity configuration [7].

<figure><img src="image_2.png" /><figcaption>**Fig. 1** (a) Scheme of the simulated Kerr comb fiber laser. (b) Artistical view of a programmable delay-line (PDL). (c-g) Soliton spectra obtained with the same MLL cavity but changing the PDL configuration. The oscillation harmonic ($N_h$) is varied from the 8th to the 128th. At equal harmonic number, the PDL also allows optical spectrum reshaping, as depicted on (c) where two different spectrums (blue & orange) are obtained by adjustment of the PDL voltages.</figcaption></figure>

The considered PDL is composed of two optical paths: a short and a long arm (the long arm being used as delay-line) locally coupled by a set of Mach-Zehnder Interferometers (MZI) (Fig.1b). The MZI are used as variable couplers and allow to control the cavity round trip delay of the Mode-Locked cavity. To highlight the potential of such a device, we present a numerical study based on experimentally realistic cavity parameters (PDL with a unitary delay of 4 ps, Fabry-Pérot Resonator of 1024 ps period and 5 MHz FWHM resonances, fiber cavity of 102.4 ns period), demonstrating that the repetition rate of a Kerr comb laser can be multiplied from the 2nd harmonic to the 128th, by merely adjusting the coupling ratio of the MZI included in our PDL. The MLL repetition rate can thus be tuned from 976 MHz to 125 GHz (Fig.1c). In total 256 steady-states can be reached within a single cavity configuration. In this case, the PDL not only provide a tunability on the repetition rate, but also yield control over the optical spectrum generated for a given harmonic number (Fig.1c). Here, the nested architecture includes an optical resonator as well as a photonic device used as programmable delay-line, which allows for controlling the repetition rate of a passively MLL over a GHz-THz range via a temporal interleaving process. Finally, the PDL can also be considered as a 2x2 ports device, which can be exploited to couple the Kerr comb laser to a second fiber cavity. We further discuss potential experimental implementation and how a Raman fiber laser pumped by the Kerr comb laser can be achieved, allowing for a fully programmable comb with tunable repetition rate and optical carrier frequency.

## References

[1] D. Kuizenga and A. Siegman, "FM and AM mode locking of the homogeneous laser-Part I: Theory," IEEE QJE 6, 694 (1970).

[2] A.P. Ippen, C.V Shank, A. Dienes, "Passive mode locking of the CW dye laser," Appl. Phys. Lett 21, 348 (1972).

[3] M. Simpson, et al., "Menlo System' ORS Ultrastable Laser System: A portable solution for state-of-the-art performance in high-precision measurements," (2023)

[4] T. Herr, et al., "Universal formation dynamics and noise of Kerr-frequency combs in microresonators," Nature Photon. 6, 480 (2012).

[5] H. Bao, A. Cooper, et al., "Laser cavity-soliton microcombs," Nature Photon. 13, 384 (2019).

[6] B. Wetzel, et al., "Customizing supercontinuum generation via on-chip adaptive temporal pulse-splitting," Nat. Commun. 9, 4884 (2018).

[7] L.A. Lugiato et al., "From the Lugiato-Lefever equation to microresonator-based soliton Kerr frequency combs," R. Soc. A. 376, 20180113 (2018).