Lasers are central to technologies ranging from telecommunications and medical diagnostics to industrial sensing, optical data storage and scientific instrumentation. Yet many high-performance laser structures depend on carefully engineered layers deposited under vacuum, often using energy-intensive equipment and tightly controlled manufacturing conditions. Organic materials can provide an attractive alternative because they are lightweight, chemically tunable and compatible with printing or coating methods. Their practical promise, however, depends on whether they can be integrated into optical cavities with sufficiently low losses and high precision to support advanced light-confinement effects.

The new device addresses that challenge by using spin coating to build every essential component of the microcavity. In spin coating, a liquid solution containing the desired material is placed on a rotating substrate. Centrifugal forces spread the solution into a thin, uniform film, while evaporation leaves behind a solid layer. By repeating the process with carefully selected materials, the researchers fabricated both the cavity mirrors and the organic light-emitting layer without relying on vacuum deposition. The approach is comparatively simple, scalable and compatible with solution-processable materials that could eventually be adapted for larger-area photonic manufacturing.

At the heart of the device is an optical microcavity, a structure designed to confine light between reflective mirrors. When the cavity is tuned correctly, photons can bounce back and forth many times, increasing their interaction with the organic molecules inside the structure. Under ordinary conditions, light is emitted by molecules and then escapes or propagates independently. In the strong light–matter coupling regime, the interaction becomes sufficiently intense and rapid that the photon and molecular excitation can no longer be treated as separate entities. Instead, they form new energy states called polaritons.

This hybrid character gives polaritons unusual properties. They inherit the low effective mass and ability to move rapidly associated with photons, while also retaining some of the interaction and material sensitivity of molecular excitations. When many polaritons occupy the same quantum state, they can produce highly directional and coherent emission resembling lasing. Unlike a conventional laser, in which stimulated emission is dominated by photons acting on excited atoms or molecules, a polariton laser is governed by the collective behaviour of these mixed light–matter states. The University of Turku team was able to observe this form of lasing in a fully solid-state structure made through liquid-based processing.

The researchers also discovered a striking optical response when the device was driven with intense pulsed light. Rather than remaining concentrated near the centre of the optically excited region, the emitted light redistributed outward and developed a ring-shaped pattern. This effect is linked to nonlinear polariton interactions, which become important as the density of polaritons increases. Polaritons can influence one another through their matter component, altering the local energy landscape and causing them to move away from regions of high density. What begins as a microscopic interaction therefore appears as a macroscopic transformation in the shape of the emitted beam.

The ring-like emission was reversible and could be adjusted by changing the optical design of the cavity. Small modifications to the cavity structure can alter the photon energy, the strength of light–matter coupling and the rate at which polaritons propagate or escape. This tunability gives the researchers a practical method for controlling nonlinear behaviour without changing the underlying organic material. Such visual and controllable effects could make the platform particularly valuable for studying polariton physics, because complex interactions become directly observable through the geometry and intensity of the emitted light.

The demonstration is significant not only because it produces a new type of organic laser, but also because it lowers the barrier to experiments in a rapidly developing field. Polariton devices have attracted interest for their potential in low-energy optical computing, nonlinear signal processing, switches and other forms of photonic technology. Many experimental systems, however, require elaborate fabrication facilities and highly specialized materials. A microcavity that can be assembled through solution processing could make polariton research more accessible to laboratories and manufacturing environments that do not possess sophisticated vacuum-deposition infrastructure.

The researchers emphasize that the current device remains an optically pumped laboratory system, meaning that an external laser is required to provide the energy needed for emission. The longer-term goal is to develop organic polariton lasers that can be driven electrically, which would be an important step toward practical devices. Electrical operation introduces additional challenges, including efficient charge injection, management of heat and preservation of strong light–matter coupling under operating conditions. Nevertheless, the new result shows that a liquid-based fabrication route can produce the optical quality needed for polariton lasing and nonlinear emission effects, offering a promising foundation for future organic photonic technologies.

Subject of Research: Fully solution-processed organic microcavity laser operating in the strong light–matter coupling regime

Article Title: A fully solution-processed organic microcavity laser in the strong light-matter coupling regime

Web References: https://doi.org/10.1038/s41467-026-75118-1

References: Nature Communications, DOI: 10.1038/s41467-026-75118-1

Image Credits: Mikael Nyberg

Keywords

Organic laser, polariton laser, solution processing, microcavity, strong light–matter coupling, nonlinear photonics, spin coating, organic photonics, University of Turku, Nature Communications

The essence of this breakthrough lies in the creation and deployment of what the researchers call a multimode photonic lantern (MM PL), a device meticulously engineered using advanced 3D-printing techniques at the microscale. Photonic lanterns traditionally serve as optical interfaces that merge several single-mode inputs into a multimode waveguide. However, this new “N-MM PL” design uniquely accommodates multiple multimode VCSEL sources simultaneously, fundamentally redefining the operational paradigm for photonic lanterns. Unlike their predecessors, these lanterns effectively multiplex dozens of multimode laser outputs while preserving brightness and ensuring highly efficient coupling to multimode fibers.

In practical terms, the team demonstrated remarkable photonic lantern variants capable of integrating the light from 7, 19, and even 37 distinct VCSEL sources. Each VCSEL exhibits complex spatial mode structures, lasing across six spatial modes, which culminates in effective support for up to 222 spatial modes within a single multimode fiber. This massive-scale multiplexing represents a formidable advancement in optical multiplexing capacity, surpassing conventional methods both in scale and efficiency and enabling far more concentrated laser arrays without the typical penalties of alignment complexity or modal mismatch.

The manufacturing process hinges on precision 3D nanoprinting, allowing the creation of devices less than half a millimeter long—a dramatic size reduction compared to conventional bulky beam combining setups. This compact form factor does not sacrifice performance; on the contrary, it delivers exceptionally low insertion losses, registering as minimal as -0.6 dB for the 19-input lantern and a mere -0.8 dB for the 37-input system. Such low losses are critical in maintaining overall system efficiency and brightness, which directly translates into higher power delivery and improved beam quality in applications spanning industrial laser machining, medical laser systems, and advanced telecommunications.

A critical challenge in previous optical beam combining technologies stemmed from coupling inefficiencies and the inability to handle multimode beams generated by high-power VCSEL arrays. Traditional photonic lanterns were intrinsically single-mode, incompatible with the multimode nature of these VCSEL sources. The research team at Hebrew University ingeniously designed an adiabatic transition within the lantern structure, facilitating a seamless and loss-minimized conversion of multiple few-mode laser outputs into a single multimode fiber. This method preserves the modal richness and brightness of the combined beam, avoiding degradation commonly associated with relay lenses or other beam shaping techniques.

The implications of this research extend deeply into optical communications, where the preservation of modal capacity and brightness is paramount for maximizing data throughput and minimizing transmission losses. Indeed, by harnessing a highly scalable, compact, and efficient photonic lantern, fiber networks could achieve significantly enhanced performance without complex infrastructure overhauls. Moreover, the technology introduces a new dimension to high-power laser systems, where managing heat dissipation and beam quality simultaneously remains a stubborn obstacle. This lantern’s ability to combine many high-power sources without sacrificing optical integrity is poised to unlock fresh industrial and research opportunities.

This advancement is the product of insightful collaboration between the Hebrew University, Civan Lasers, and financial backing from the Israel Innovation Authority. Spearheaded by Ph.D. student Yoav Dana under the mentorship of Professor Dan M. Marom, the team’s work crystallizes years of progress in integrated optics, laser physics, and additive manufacturing. The cross-disciplinary expertise allowed for an inventive fusion of theoretical design and experimental validation, culminating in a demonstrator device whose length measures only 470 micrometers—a scale few optical multiplexers can parallel.

From a technical standpoint, the device’s operation relies on precise modal matching between the multimode inputs and the multimode output fiber. Each VCSEL array emits beams composed of multiple spatial modes, which are notoriously challenging to combine without incurring modal dispersion or brightness loss. The MM photonic lantern accomplishes this by implementing an adiabatic taper geometry that gradually transforms the spatial modes’ distributions, thus preserving the spatial coherence and brightness as these modes are delicately funneled into a fiber that supports all these parallel channel modes simultaneously.

This compact lantern also significantly relaxes the alignment precision typically required for coupling multimode beams into fibers. The intricate 3D-printed waveguide structure internally redistributes the optical paths with nanometer accuracy, easing system integration complexity while enhancing robustness against environmental perturbations—an essential feature for real-world deployment in industrial and communication systems often exposed to mechanical and thermal stresses.

The significance of this achievement is not only in the scale or the compactness but also in its practical applicability. By offering a pathway to spatially multiplexed multimode lasers with minimal insertion loss and preserved brightness, the research opens avenues to scalable, high-brightness laser arrays suitable for next-generation laser manufacturing, aerospace optical systems, and secure high-capacity fiber networks. The lantern’s potential to serve as a universal interface between multimode semiconductor lasers and fibers signals a paradigm shift for photonic system design.

Looking forward, scaling this technology further could facilitate even denser laser arrays, dramatically increasing the combined optical power deliverable through fiber networks. Such scalability ensures this innovation is future-proof, accommodating ongoing trends in miniaturization and integration in photonics. Whether applied to boosting fiber optic communication bandwidth or enhancing laser machining precision, the 3D-printed multimode photonic lantern epitomizes the fusion of cutting-edge fabrication techniques with profound optical design principles.

In summary, the Hebrew University research team has presented a transformative solution to a long-standing photonics challenge: efficiently combining the output of many multimode VCSELs into a single fiber with minimal loss and preserved brightness. The microscale 3D-printed multimode photonic lantern breaks new ground in scalability, efficiency, and compactness, promising broad impacts across scientific and industrial photonics. This work illustrates the power of interdisciplinary collaboration and advanced manufacturing to redefine optical technologies for the next wave of innovation.

Subject of Research: Not applicable

Article Title: Massive-scale spatial multiplexing of multimode VCSELs with a 3D-printed photonic lantern

News Publication Date: 10-Mar-2026

Web References: 10.1038/s41467-026-70458-4

Image Credits: Ksenia Shukhin

Keywords

Photonics, Optical materials, Fiber optics, Laser systems, Physics