Description

Farsince 400G QSFP‑DD to 4×QSFP28 AOC is a factory‑terminated multimode fiber harness that fan‑outs a single QSFP‑DD host interface to four QSFP28 optical ends. The QSFP‑DD side operates eight 50‑Gb/s PAM4 lanes at 850 nm (SR8), mapped into four groups of 4×25G NRZ for each QSFP28 leg (SR4). It connects spine/leaf switches, accelerator nodes and servers where a 400G port needs to be broken into four 100G ports without separate transceivers and patch cords. Typical deployments include leaf‑to‑TOR aggregation, AI/HPC clusters and high‑density rows within the same rack or across adjacent racks.

The lightweight optical construction reduces cable bulk and eliminates EMI concerns common to copper fanouts, easing airflow and maintenance in congested trays. Hot‑pluggable pull‑tab connectors and standardized QSFP‑DD/QSFP28 mechanics simplify service in dense chassis. Power draw is within 10 W per complete cable from a 3.3 V supply, with monitoring via CMIS over I2C and diagnostics per SFF‑8636. Farsince supports project‑matched overall and leg lengths, labeling/serialization and kitting to align with site installation practices.

Specifications

• Product Type: QSFP‑DD to 4×QSFP28 Active Optical Cable (AOC)
• Host Interface: 1× QSFP‑DD, MSA compliant, hot‑pluggable
• Device Interface: 4× QSFP28, MSA compliant, hot‑pluggable
• Data Rate: 400 Gb/s aggregate; each leg 100 Gb/s
• Lane Mapping: QSFP‑DD 8×50G PAM4 (SR8) to QSFP28 4×25G NRZ (SR4 per leg)
• Electrical Interface: 400GAUI‑8 on host; CAUI‑4 on each leg
• Wavelength: 850 nm VCSEL/PIN optics
• Cable Length: 1–50 m options
• Power Consumption: ≤10 W per cable
• Operating Temperature: 0–70°C
• Management: CMIS over I2C; diagnostics per SFF‑8636
• Installation: Pull‑tab latches; observe minimum bend radius
• Application: Breakout of a 400G port to four 100G switch/NIC connections
• Compliance: RoHS, REACH
• Customization: Overall length, leg lengths, labeling/serialization, kitting