Osaka Single-Chip LED Beats 50% Polarization Limit
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- University of Osaka researchers, collaborating with ULVAC, Inc. and Ritsumeikan University, built a single-chip circularly-polarized LED by combining a semipolar InGaN light-emitting structure with a stripe-shaped silicon nitride (SiNₓ) metasurface integrated directly on the chip surface.
- The device hit a 68% linear-to-circular polarization conversion efficiency, exceeding the 50% theoretical ceiling that has limited conventional circularly-polarized LEDs, which can extract only one circular polarization component from unpolarized light.
- Optical measurements at room temperature recorded a circular polarization degree of 0.27 at 408 nm, with experimental results closely matching three-dimensional electromagnetic simulations of the device.
- Prof. Shuhei Ichikawa, the study's senior author, said the team obtained high efficiency 'simply by integrating a single-layer metasurface,' eliminating the need for external bulk optical components.
- The all-inorganic structure is compatible with existing semiconductor manufacturing processes, pointing toward durable, compact, and scalable polarized light sources rather than one-off lab prototypes.
- Published in Optical Materials Express (DOI: 10.1364/ome.588632), the work targets applications in AR/VR, 3D displays, quantum communication, and optical security.
Why it matters: The 50% conversion-efficiency ceiling has forced prior circularly-polarized light sources to rely on bulky external polarizers, blocking miniaturization. A single-chip design that clears that bar at 68% — using only inorganic materials compatible with existing fabs — removes a long-standing bottleneck for shrinking AR glasses, quantum links, and 3D displays into practical form factors.
