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Main Authors: Kullig, Julius, Zhong, Qi, Wiersig, Jan, El-Ganainy, Ramy
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2510.23846
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author Kullig, Julius
Zhong, Qi
Wiersig, Jan
El-Ganainy, Ramy
author_facet Kullig, Julius
Zhong, Qi
Wiersig, Jan
El-Ganainy, Ramy
contents One of the most fundamental questions in laser physics is the following: Which mode of an optical cavity will reach the lasing threshold first when gain is applied? Intuitively, the answer appears straightforward: When a particular mode is both temporally well confined (i.e., exhibits the highest quality factor) and experiences initially the largest increase of the modal gain, it is naturally expected to lase first. However, in this work, we demonstrate that this intuition can fail in surprising ways. Specifically, we show that in the presence of non-Hermitian degeneracies, known as exceptional points, the expected mode hierarchy can be dramatically altered. These spectral singularities can give rise to counterintuitive mode switching, where a mode with a lower quality factor and initially smaller increase of modal gain reaches the lasing threshold ahead of a more favorable competitor. Remarkably, this effect can occur even under spatially uniform pumping, underscoring the subtle and profound influence of non-Hermitian physics on lasing dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23846
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exceptional Points and Lasing Thresholds: When Lower-Q Modes Win
Kullig, Julius
Zhong, Qi
Wiersig, Jan
El-Ganainy, Ramy
Optics
One of the most fundamental questions in laser physics is the following: Which mode of an optical cavity will reach the lasing threshold first when gain is applied? Intuitively, the answer appears straightforward: When a particular mode is both temporally well confined (i.e., exhibits the highest quality factor) and experiences initially the largest increase of the modal gain, it is naturally expected to lase first. However, in this work, we demonstrate that this intuition can fail in surprising ways. Specifically, we show that in the presence of non-Hermitian degeneracies, known as exceptional points, the expected mode hierarchy can be dramatically altered. These spectral singularities can give rise to counterintuitive mode switching, where a mode with a lower quality factor and initially smaller increase of modal gain reaches the lasing threshold ahead of a more favorable competitor. Remarkably, this effect can occur even under spatially uniform pumping, underscoring the subtle and profound influence of non-Hermitian physics on lasing dynamics.
title Exceptional Points and Lasing Thresholds: When Lower-Q Modes Win
topic Optics
url https://arxiv.org/abs/2510.23846