Optical waves propa­gating through air or multi-mode fiber can be patterned or decomposed using orthogonal spatial modes, with far-ranging appli­cations in imaging, communi­cation, and directed energy. Yet the systems that perform these wavefront mani­pulations are cumbersome and large, restricting their utilization to high-end applications. The development of a „Free-Standing Microscale Photonic Lantern Spatial Mode (De-)Multiplexer using 3D Nano­printing“, as revealed by a recent study, marks a signi­ficant advancement in photonic technology.

This spatial multi­plexer, charac­terized by its compactness, minimal footprint, and ability to directly print on, and adhere to, photonic circuits, optical fibers, and optoelectronic elements as lasers and photo­detectors, opens new oppor­tunities in system integration and adoption of the techno­logy in future high-capacity communi­cation systems and demanding imaging modalities. The work of Yoav Dana, Dan Marom and his team at the Hebrew University of Jerusalem, in partnership with scientists from Nokia Bell Labs, resulted in the development and demon­stration of the new micro­scale photonic lantern. The device was fabricated by a 3D nano-printing technique utilizing direct laser writing, applied directly onto an optical fiber tip.

Photonic lantern devices convert between optical waves containing a super­position of modes or distorted wavefronts and array of separated single mode optical signals. The technology stands out as a promising contender to enable space division multi­plexing (SDM) in high-capacity future optical communi­cation networks, as well as in imaging and other appli­cations requiring the spatial manipulation of optical waves.

Harnessing the capa­bilities of 3D nano-printing and employing high-index contrast waveguides, the researchers have developed a compact and versatile device that can be printed onto nearly any solid platform with fine accuracy and high fidelity, enabling its seamless inte­gration into a variety of techno­logical contexts. The approx. 100 micrometer scale device stands in large contrast to traditional photonic lanterns based on weakly guiding waveguides that are milli­meters to centi­meters long, making inte­gration with micro-scale photonic systems very challenging.

“The development of this “Free-Standing Microscale Photonic Lantern Spatial Mode (De-)Multi­plexer” represents a signi­ficant advancement in our ability to enable and adopt spatial multi­plexing for diverse optical systems and appli­cations,” said Dan Marom. “This breakthrough makes space division multi­plexing techno­logy much more accessible and amenable towards integration, opening up new possi­bilities for optical communi­cation and imaging appli­cations, to name a few.”

The researchers have presented the device design using genetic algorithms, fabrication onto a fiber tip, and charac­terization of a six-mode mixing, 375 microns long photonic lantern capable of converting between six single-mode inputs into a single six-mode waveguide. Despite its compact size, the device exhibits low insertion loss (-2.6 dB), low wavelength sensi­tivity and low polari­zation and mode-dependent losses (-0.2 dB and -4.4 dB respectively). (Source: HUJI)

Reference: Y. Dana et al.: Free-standing microscale photonic lantern spatial mode (De-)multiplexer fabricated using 3D nanoprinting, Light: Sci. Appl. 13, 126 (2024); DOI: 10.1038/s41377-024-01466-6

Link: Photonic Devices Lab, Institute of Applied Physics, Hebrew University of Jerusalem, Jerusalem, Israel