English (UK)
To observe farther and in greater detail, telescopes need to capture more and more light. One way to achieve this is to build larger instruments, but this option implies huge technological and economic challenges. Another possibility is to combine the capabilities of several smaller telescopes and to make them work as a single unit. To achieve this, a fundamental challenge must be overcome: precisely collecting and combining the light coming from each telescope.
An international team led by the Institute of Astrophysics of Andalusia (IAA-CSIC), with participation from Calar Alto Observatory staff, has taken an important step toward addressing this challenge with a new application of the so-called photonic lanterns—small fiber-optic devices capable of manipulating and transporting the light with great efficiency.
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“Photonic lanterns used until now split the light traveling through an optical fiber into several independent signals,” explains Marina Centenera, PhD student (FPI contract associated to the Severo Ochoa award) at IAA-CSIC and leader of the study. “Our new device works the other way around: it combines the light from seven optical fibers into a single output, preserving the properties necessary to efficiently harness the light captured by the telescopes.”
Laboratory tests show that the new device successfully combines the signals from the seven fibers while preserving more than 90% of the light. This high level of efficiency is particularly important for astronomical applications, where capturing every amount of light is crucial for observing and studying faint objects with greater precision.
The results, published in the Optics Letters journal, constitute the first eveer demonstration of a photonic coupler specifically designed to combine multiple multimode inputs into a single multimode output. “The new design allows us to efficiently work with the light collected by telescopes after it has passed through Earth’s atmosphere, paving the way to combine signals from multiple telescopes and jointly leverage their observational capabilities,” notes Pedro J. Amado, a researcher at the IAA-CSIC who is part of the project.
FROM SEVEN SMALL TELESCOPES TO A SINGLE SIGNAL
The new technology was developed as part of Photonic E-MARCOT, a project investigating how to combine light from several small telescopes so they can work together. Its demonstrator, MARCOT-Pathfinder, is installed at Calar Alto Observatory and consists of seven telescope units.
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“For Calar Alto, this development represents a concrete step toward the observatories of the future, based on modular, scalable architectures supported by new photonic technologies. MARCOT-Pathfinder allows us to validate these solutions under real astronomical conditions and move toward larger-scale systems capable of efficiently combining the light from multiple telescopes,” says Jesús Aceituno, Calar Alto Observatory director.
Each of the seven telescopes can transmit the light captured through an optical fiber. The new photonic lantern combines these seven inputs into a single output, which can then feed the scientific instrumentation. Its design also allows it to work with multimode fibers, capable of collecting starlight even when it has been distorted by atmospheric turbulence.
“Being able to combine the light from multiple telescopes with very limited losses is one of the technological steps needed to demonstrate that this concept can work. Thus, our goal is to explore the extent to which photonics can enable relatively small telescopes to work together efficiently,” explains Marina Centenera.
The images obtained through microscopy allow for direct observation of the result of this process. At the device’s output end, the seven fibers carrying the light converge into a single region, whose distinctive flower-like shape reflects how the signals from the different inputs merge to form a single output.
This work is part of joint research conducted by the IAA-CSIC and the Calar Alto Observatory in the field of astrophotonics, including the IAA-CAHA Astrophotonics Laboratory, created to develop, characterize, and integrate new photonic technologies applied to astronomical instrumentation.
This development was made possible thanks to an international collaboration between the IAA-CSIC, the Calar Alto Observatory, the University of Sydney, and the Leibniz Institute for Astrophysics Potsdam (AIP), which contributed their expertise in astrophotonics and optical fiber technology. The photonic lanterns were manufactured at the Sydney Astrophotonic Instrumentation Laboratories (SAIL), while their design, characterization, and astronomical application were developed within the framework of Photonic E-MARCOT and MARCOT-Pathfinder.
POSSIBLE APPLICATIONS BEYOND ASTRONOMY
Although the technology was developed for astronomical applications, its ability to efficiently combine light from different channels could find applications in other fields of photonics, such as optical communications, remote sensing, or optical sensors.
The IAA-CSIC and its collaborating institutions have filed a patent application for the device, aiming at exploring future applications and avenues for technology transfer.
The next step will be to integrate the new photonic lantern into MARCOT-Pathfinder to test its performance with light from real astronomical objects and to progress in the validation of the system.
“We are developing and testing the necessary components to determine whether, in the future, the combination of modular telescopes and photonic technologies can offer a different and more scalable way to build the modular observatories of the future,” concludes Pedro J. Amado (IAA-CSIC).
REFERENCE
Centenera et al. (2026) “Demonstration of a multimode-to-multimode photonic lantern for astronomy,” 10.1364/OL.609358
CONTACTS
- Calar Alto observatory (CAHA) Jesús Aceituno -
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COMMUNICATION- CALAR ALTO OBSERVATORY
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El Observatorio de Calar Alto es una de las infraestructuras que pertenecen al mapa de Infraestructuras Científicas y Técnicas Singulares (ICTS), aprobado por el Consejo de Política Científica, Tecnológica y de Innovación (CPCTI) el 11 de marzo de 2022.
