A new technical paper titled “Monolithically Integrated Optical Through-Silicon Waveguides for 3D Chip-to-Chip Photonic Interconnects” was published by researchers at the Technical University of Applied Sciences Wildau, TU of Applied Sciences Mittelhessen, TU Ilmenau, Brandenburg University of Technology and Fraunhofer IPMS.
Abstract
“The scaling limitations of electrical interconnects are driving the demand for efficient optical chip-to-chip links. We report the first monolithic integration of air-clad optical through-silicon waveguides in silicon, fabricated via Bosch and cryogenic deep reactive-ion etching. Rib, single-bridge, and double-bridge designs with 50 μm cores and up to 150 μm propagation lengths have been evaluated. Cryogenic-etched rib waveguides achieve the highest median transmission (66%, -1.80 dB), compared to Bosch-etched ribs (62%, -2.08 dB). Across all geometries, 3 dB alignment windows range from 9.3 μm to 49.2 μm, with Bosch-etched double-bridge waveguides providing the broadest tolerance. We show that geometric fidelity outweighs sidewall roughness for transmission and alignment in these large-core, multimode optical through-silicon waveguides. This technology provides a scalable, complementary metal-oxide semiconductor-compatible pathway toward 3D photonic interconnects.”
Find the technical paper here. September 2025.
Villasmunta, Francesco, Patrick Heise, Manuela Breiter, Sigurd Schrader, Harald Schenk, Martin Regehly, and Andreas Mai. “Monolithically Integrated Optical Through-Silicon Waveguides for 3D Chip-to-Chip Photonic Interconnects.” IEEE Journal of Selected Topics in Quantum Electronics (2025). Creative commons license.
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