Researchers have achieved a groundbreaking milestone in 3D photonics, marking a significant advancement in the field of optical technology. This achievement, detailed in a recent study published in Nature Communications, involves the development of a microscopic 3D-printed optical device that can efficiently combine light from multiple small semiconductor lasers into a single multimode optical fiber with minimal loss. The team, led by Ph.D. student Yoav Dana and Professor Dan M. Marom at the Institute of Applied Physics at the Hebrew University of Jerusalem, Israel, has introduced a novel 3D-printed microscale Photonic Lantern (PL) designed for the efficient incoherent combining of multimode sources.
This innovation addresses a long-standing challenge in the field: coupling light from large Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays, each emitting in multiple modes, into multimode fibers while maintaining brightness and minimizing alignment constraints. The research, conducted in collaboration with Civan Lasers and funded by the Israel Innovation Authority, showcases a remarkable breakthrough in system scale and miniaturization for optical beam combining apparatus, which are crucial for high-power laser systems.
Key Advancements
- First Multimode Photonic Lantern (MM PL): The team has successfully realized a novel "N-MM PL" architecture that supports multiple multimode VCSEL sources multiplexed into a single high mode count waveguide. This is a significant departure from traditional photonic lanterns, which are designed for single-mode inputs.
- Massive Scalability: The researchers demonstrated PLs capable of multiplexing 7, 19, and even 37 VCSEL sources, each lasing across six-spatial modes, into a single multimode optical fiber. This supports a total of up to 222 spatial modes, showcasing the technology's potential for high-density optical communication.
- High Efficiency at Diminutive Size: The devices achieved low coupling losses into standard 50 μm multimode fiber, as low as -0.6 dB for 19-input PLs and -0.8 dB for 37-input PLs. The entire PL required less than ½ mm in length, which is significantly smaller than competing optical multiplexing systems.
- Preserved Brightness: Unlike traditional relay lens systems, this "N-MM PL" architecture matches modal capacity to preserve brightness, a critical factor for high-performance optical systems.
Technical Breakthrough
The traditional challenge of interfacing photonic lanterns with multimode outputs of high-power VCSEL arrays has been overcome by the Hebrew University team. They designed an adiabatic transition that converts multiple few-mode sources into a single multimode fiber with matched degrees of freedom. Despite the massive-scale capability, these devices remain incredibly compact, with the 37-input PL measuring only 470 μm in length.
This breakthrough has far-reaching implications for various applications, including high-power laser systems, optical communications, and other photonic technologies where efficient power delivery through fibers is essential. The ability to combine light from multiple lasers in a compact and efficient manner opens up new possibilities for enhancing the performance and scalability of these systems.
In my opinion, this research represents a significant leap forward in the field of 3D photonics, offering a promising solution to a long-standing challenge. The potential for scalable and efficient light combining in a compact form factor is particularly exciting, as it could lead to advancements in high-performance optical systems and enable new applications in the future.
