Purely equatorial lasing in spherical liquid crystal polymer microlasers with engineered refractive index gradient

Fuente: arXiv
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Autori principali: Ripp, David, Pathak, Nachiket, Titze, Vera M., Mischok, Andreas, Schubert, Marcel
Natura: Preprint
Pubblicazione: 2026
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author Ripp, David
Pathak, Nachiket
Titze, Vera M.
Mischok, Andreas
Schubert, Marcel
author_facet Ripp, David
Pathak, Nachiket
Titze, Vera M.
Mischok, Andreas
Schubert, Marcel
contents Liquid crystal whispering gallery mode microlasers show high sensitivity to external stimuli and distinct spectral features, rendering them ideally suited for various sensing applications. They also offer intrinsic anisotropic optical properties, which can be used to shape and manipulate light even inside spatially highly symmetric structures. Here, we report the synthesis and detailed optical characterization of a spherical bipolar liquid crystal polymer microlaser that tightly confines the optical path of whispering gallery modes to the equatorial plane. By controlled anchoring of the liquid crystal mesogens followed by polymerization, a fixed refractive index gradient is formed within the spherical microcavity. Consequently, only transverse electric (TE) modes oscillating in the equatorial plane experience the high extraordinary refractive index, allowing to confine lasing into a single plane. Furthermore, we observe that the refractive index gradient causes a characteristic splitting of the TE modes. By combining hyperspectral imaging and analytical modeling, we demonstrate that the observed splitting is caused by lifting of the energy degeneracy of higher order azimuthal laser modes, enabling direct insights into the complex interplay of refractive index gradients and resulting whispering gallery mode confinement. In addition, the unique ability to confine lasing of a spherical microbead into only a single plane makes these microlasers independent of the exact position of the pump beam, which allows consistent localized sensing especially in combination with fast point scanning microscopes or inside highly dynamic biological environments.
format Preprint
id arxiv_https___arxiv_org_abs_2601_12673
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Purely equatorial lasing in spherical liquid crystal polymer microlasers with engineered refractive index gradient
Ripp, David
Pathak, Nachiket
Titze, Vera M.
Mischok, Andreas
Schubert, Marcel
Optics
Materials Science
Liquid crystal whispering gallery mode microlasers show high sensitivity to external stimuli and distinct spectral features, rendering them ideally suited for various sensing applications. They also offer intrinsic anisotropic optical properties, which can be used to shape and manipulate light even inside spatially highly symmetric structures. Here, we report the synthesis and detailed optical characterization of a spherical bipolar liquid crystal polymer microlaser that tightly confines the optical path of whispering gallery modes to the equatorial plane. By controlled anchoring of the liquid crystal mesogens followed by polymerization, a fixed refractive index gradient is formed within the spherical microcavity. Consequently, only transverse electric (TE) modes oscillating in the equatorial plane experience the high extraordinary refractive index, allowing to confine lasing into a single plane. Furthermore, we observe that the refractive index gradient causes a characteristic splitting of the TE modes. By combining hyperspectral imaging and analytical modeling, we demonstrate that the observed splitting is caused by lifting of the energy degeneracy of higher order azimuthal laser modes, enabling direct insights into the complex interplay of refractive index gradients and resulting whispering gallery mode confinement. In addition, the unique ability to confine lasing of a spherical microbead into only a single plane makes these microlasers independent of the exact position of the pump beam, which allows consistent localized sensing especially in combination with fast point scanning microscopes or inside highly dynamic biological environments.
title Purely equatorial lasing in spherical liquid crystal polymer microlasers with engineered refractive index gradient
topic Optics
Materials Science
url https://arxiv.org/abs/2601.12673