Within the framework of general relativity, a gravitational white hole is posited as a hypothetical spatial region that is inaccessible from external vantage points. This concept represents the inverse of a black hole, from which neither light nor information can egress. Investigators affiliated with the University of Southampton, Nanyang Technological University, and Texas A&M University have successfully engineered an optical apparatus that exhibits striking parallels to these theoretical cosmic entities. Depending on the polarization of incident light, this device displays the capacity to either completely absorb such radiation (functioning as an optical black hole) or entirely repel it (operating as an optical white hole), irrespective of its wavelength.
A double-prism configuration, featuring an interposed thin film, is depicted as a dark plane capable of absorbing light, thereby emulating a gravitational black hole. The image is credited to Nina Vaidya from the University of Southampton.
The recently conceived apparatus operates as either an optical black hole or an optical white hole, predicated upon a phenomenon known as coherent perfect absorption of electromagnetic waves.
In a manner analogous to the behavior observed in astronomical black and white holes, this optical construct has the capability to either absorb or reject light with near-total efficiency, a characteristic dictated by its polarization.
The operational mechanism of the device involves the orchestration of incident light waves into a standing wave pattern. Subsequent interactions with an exceedingly thin absorptive layer result in either perfect absorption or unimpeded transmission, contingent upon the polarization state of the incoming light.
Stated plainly, its functionality mirrors that of a celestial body that either engulfs or repels photons.
“The allure and profound scientific curiosity surrounding cosmic phenomena, particularly black holes, have captivated the human intellect for innumerable epochs,” remarked Professor Nina Vaidya of the University of Southampton.
“Analogous systems provide invaluable avenues for exploring fundamental physics, especially concerning remote astronomical objects such as black holes. This is due to the remarkable recurrence of similar mathematical frameworks and physical principles across diverse systems, ranging from cosmic phenomena to devices operating at nano- and pico-scales.”
“We are introducing the conceptual framework of optical black and white holes, which are engineered to deterministically absorb nearly all incident light of a specific polarization while simultaneously repelling light with the orthogonal polarization.”
“This achievement is underpinned by our experimental validation of broadband coherent perfect absorption within compact device architectures. This is facilitated by spatial coherence and constructive interference, with polarization selectivity being imparted by the geometric phase acquired by the interfering beams.”
The proof-of-concept investigations conducted by the research team provide empirical evidence that this optical device possesses the ability to manipulate electromagnetic waves in a manner that closely recapitulates the characteristics of gravitational black and white holes.
Theoretical simulations demonstrate a complete absence of light reflection from the device when configured as a black hole analog. Conversely, for the white hole analog, these simulations reveal the formation of a standing wave arising from the constructive interference between incident and reflected light.
The findings derived from this research offer profound insights and reveal promising avenues for the controlled manipulation of light-matter interactions, potentially paving the way for a wide spectrum of practical applications.
“Our optical device can serve as a valuable analog for investigating and comprehending the intricate physics governing these distant celestial phenomena. Furthermore, it presents a viable platform for numerous potential applications involving the precise control of electromagnetic waves and the amplification of light-matter interactions. These applications encompass areas such as advanced detection systems, efficient energy conversion, sophisticated multispectral camouflage, and cutting-edge stealth technologies, among others,” elaborated Professor Vaidya.
The scientific contributions of this research collective have been formally documented and disseminated in the esteemed journal Advanced Photonics. The publication can be accessed via the following link: work.
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Eric Plum et al. 2025. Optical analog of black and white gravitational holes. Advanced Photonics 7 (2): 025001; doi: 10.1117/1.AP.7.2.025001
