2025 · 10·Photonics Research · 13(10)·First author·Editor's Pick · IF 7.2

On-chip multi-band mode-division multiplexed optical interconnect using ultra-broadband inverse-designed digital metamaterials

A. Sun, Q. Li, Y. Yuan, et al.
Fudan University · HUST · Zhangjiang Lab

DOI Scholar Related work
TL;DR The first multi-band mode multiplexer (MUX) built on a digital-metamaterial structure, supporting the first three TE modes within a 6 × 4.8 µm² footprint. It keeps an exceptionally flat response across 1500–2100 nm, with measured insertion loss below 4.3 / 4.0 dB and crosstalk below −11.6 / −11.3 dB in the 1525–1585 nm and 1940–2040 nm bands, enabling 3-mode × 180 Gb/s at 1.55 µm and a record 3-mode × 114 Gb/s at 2 µm.
inverse designmode multiplexingoptical interconnectdigital metamaterialssilicon photonics
Multi-band MDM optical interconnect
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Background

Combining mode-division multiplexing (MDM) with wavelength-division multiplexing (WDM) is a compelling way to raise the shoreline density of on-chip optical interconnects. But existing on-chip MDM systems struggle to deliver large optical bandwidth, multi-band operation and ultra-compactness at the same time — limiting scalability as conventional telecom-band resources become increasingly constrained.

Device & Results

We introduce, to our knowledge, the first multi-band mode multiplexer based on a digital-metamaterial structure that supports the first three-order TE modes. The device is ultra-compact (6 × 4.8 µm²) and exhibits a flat spectral response, with simulated spectral variation below 0.94 dB across 1500–2100 nm. Measured insertion loss is below 4.3 dB (1525–1585 nm) and 4.0 dB (1940–2040 nm), with crosstalk below −11.6 dB and −11.3 dB respectively. System-level experiments reach single-wavelength 3-mode × 180 Gb/s at 1.55 µm and a record 3-mode × 114 Gb/s at 2 µm.

Highlights

  • First multi-band mode multiplexer based on a digital-metamaterial structure (3 TE modes, 6 × 4.8 µm²)
  • Flat 1500–2100 nm spectral response (variation < 0.94 dB)
  • 3 modes × 180 Gb/s at 1.55 µm; record 3 modes × 114 Gb/s at 2 µm
  • Selected as Editor's Pick in Photonics Research

Citation

A. Sun et al., "On-chip multi-band mode-division multiplexed optical interconnect using ultra-broadband inverse-designed digital metamaterials," Photonics Research, 13(10), 2025.