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arXiv · 2309.05912

Exceptional point proximity-driven mode-locking in coupled microresonators

Riku Imamura·Shun Fujii·Ayata Nakashima·Takasumi Tanabe
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Abstract

We show theoretically and numerically that mode-locking is feasible with a coupled-cavity system with gain and loss, notably, without any natural saturable absorber. We highlight that in the vicinity of the exceptional point, system $Q$ exhibits substantial modulation even with minor refractive index changes and a minimal Kerr effect contribution. Leveraging this unique behaviour, we propose an unprecedented approach wherein the lossy auxiliary cavity functions as an efficient artificial saturable absorber, thus facilitating mode-locking. This approach is not only novel, but also presents considerable advantages over conventional systems where both gain and saturable absorption are contained within a single microcavity. These benefits include reduced operational power and ease of post-adjustment, achievable through the manipulation of the coupling strength between the two microcavities.

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Riku Imamura, Shun Fujii, Ayata Nakashima, Takasumi Tanabe. 2023-09-12. Exceptional point proximity-driven mode-locking in coupled microresonators. https://arxiv.org/abs/2309.05912

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