High‑Density Silicon Photonics 400G/100G Module Design for Data Center Networks

With the rapid expansion of cloud services, data‑center campuses have grown from 100k to 300k slots, creating a demand for higher‑density 100 G networking; the solution is to develop ASIC‑based switches that can support 128 × 100 G (12.8 T) or up to 256 × 100 G (25.6 T) configurations.

Using a 25.6 T chip, a 256 × 100 G chassis would occupy 8 RU and require nine high‑speed boards, making the back‑plane complex; instead, redesigning the chip as 64 × 400 G with a 1‑in‑4 fan‑out optical module achieves the same 256 × 100 G capacity in only 2–4 RU with a single board and no back‑plane, greatly reducing cost and complexity.

The silicon‑photonic DR4/DR1 approach leverages single‑mode fan‑out modules, which offer longer reach and fewer optical channels than multimode; silicon‑photonic (SiP) chips are chosen over EML for better yield, reliability, lower cost, and broader temperature tolerance.

Two module designs were evaluated: Scheme 1 integrates a 3‑D‑packaged silicon‑photonic engine with a state‑of‑the‑art 7 nm PAM4 DSP, while Scheme 2 uses a separated‑chip approach with a 16 nm PAM4 DSP and domestically sourced optical components.

Scheme 1’s 3‑D BGA integrates MZM, PD, driver, and TIA on a single chip, consuming less than 4 W; testing showed BER < 10⁻⁸ without FEC, eye‑diagram TDECQ < 0.6 dB, and total module power under 8.9 W, outperforming most 400 G multimode modules.

Scheme 2’s separated packaging employs golden‑wire interconnects, a 5.8 W 16 nm DSP, and domestic silicon‑photonic chips, achieving up to 200 Gbps per lane (≈800 G per module) with TEDCQ < 2 dB, suitable for both short‑ and long‑reach applications.

Both approaches have distinct strengths: the integrated scheme offers higher speed balance and compact density, while the separated scheme provides flexible chip combinations, higher yield, and easier scalability, positioning silicon‑photonic modules as a key technology for future high‑performance, stable data‑center networks.

In summary, silicon‑photonic technology based on stable silicon materials will significantly enhance the reliability and density of next‑generation high‑speed networks, making it a core component for future optical‑electrical co‑packaged solutions.