Optical echoes of light near a black hole

Fuente: arXiv
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Auteurs principaux: Ju, Suting, Zhang, Jingxuan, Wang, Li-Gang
Format: Preprint
Publié: 2026
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author Ju, Suting
Zhang, Jingxuan
Wang, Li-Gang
author_facet Ju, Suting
Zhang, Jingxuan
Wang, Li-Gang
contents The light deflection under a strong gravitational field, referred to as strong gravitational lensing, provides a powerful probe of spacetime geometry. Besides, laboratory analogue models are employed to study the effects of curved spacetime and explore the design of optical devices. Here, applying the framework of analogue gravity, we reveal the behavior of the optical echo from a pulsed point-like source near a black hole, which is strongly dependent on the interplay of the black hole's photon sphere and the source's duration. We model the Schwarzschild spacetime as a Flamm paraboloid and calculate the echo response, using analytical geodesic solutions and the Huygens-Fresnel principle. Particularly, when the spatial scale of pulse duration is comparable to the photon sphere, continuous ``echo tails" appear along bright interference fringes in temporal response. Analysis in both the temporal and frequency domains reveals that these echo tails are a signature of resonance between the incoming pulse and the photon sphere. This work provides a wave-optics perspective on the interaction between dynamic sources and black holes, offering a table top window on strong gravitational lensing.
format Preprint
id arxiv_https___arxiv_org_abs_2601_02197
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Optical echoes of light near a black hole
Ju, Suting
Zhang, Jingxuan
Wang, Li-Gang
General Relativity and Quantum Cosmology
Optics
The light deflection under a strong gravitational field, referred to as strong gravitational lensing, provides a powerful probe of spacetime geometry. Besides, laboratory analogue models are employed to study the effects of curved spacetime and explore the design of optical devices. Here, applying the framework of analogue gravity, we reveal the behavior of the optical echo from a pulsed point-like source near a black hole, which is strongly dependent on the interplay of the black hole's photon sphere and the source's duration. We model the Schwarzschild spacetime as a Flamm paraboloid and calculate the echo response, using analytical geodesic solutions and the Huygens-Fresnel principle. Particularly, when the spatial scale of pulse duration is comparable to the photon sphere, continuous ``echo tails" appear along bright interference fringes in temporal response. Analysis in both the temporal and frequency domains reveals that these echo tails are a signature of resonance between the incoming pulse and the photon sphere. This work provides a wave-optics perspective on the interaction between dynamic sources and black holes, offering a table top window on strong gravitational lensing.
title Optical echoes of light near a black hole
topic General Relativity and Quantum Cosmology
Optics
url https://arxiv.org/abs/2601.02197