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400G QSFP-DD SR4
400G Optical Transceiver

400G QSFP-DD SR4

SKU / P/N: PHOS-4Q2FMS450M121
400G SR4 optical transceiver for AI data center, GPU cluster, reseller and system-integrator projects.
Data Rate
425Gbps
Form Factor
single-port QSFP-DD
Standard
SR4
Reach
40m @ OM3 / 70m @ OM4
Connector
MPO-12/APC
Max Power
8W
Spot Available Lead time: 2–4 weeks
Bulk package:
Custom Quote
Custom bulk order? Beyond 2000 pcs, mixed models or annual supply — use Custom Quote to negotiate your discount offline.

Bulk availability changes frequently. Discounts shown are indicative volume tiers — submit an RFQ to confirm the latest price, lead time and allocation. Prices are provided by quote — no public list price.

Link-up guaranteedCoded to any switch / NIC platform
Lifetime warrantyAdvance replacement
Ships from US warehouseFast, no import hassle
Per-unit testedTest report + power-on video

Product description

Generic-compatible 400GBASE-SR4 QSFP-DD PAM4 optical transceiver — multimode fiber, 850 nm, 50 m, MTP/MPO-12, DOM.

The 400GBASE-SR4 transceiver reaches up to 50 m over parallel OM4 multimode fiber through an MTP/MPO-12 connector, complying with IEEE 802.3df-2024 and the 400GAUI-8 standard.

The 400G Ethernet signal is transmitted over four parallel lanes, one wavelength per lane.

Product highlights

  • Integrated low-power DSP for stable performance at scale
  • Optimized power budget, max power consumption 8W
  • Compliant with QSFP-DD MSA and IEEE 802.3 standards
  • Supports breakout to lower-rate links for flexible fabric design
  • Backward compatible with existing QSFP form-factor ports
  • Tested on live switch / NIC platforms to ensure performance, quality and reliability

Applications

  • AI data center & GPU cluster interconnect
  • Spine-leaf switching fabric
  • Short-reach in-rack and adjacent-rack connections
  • Hyperscale, cloud and high-performance computing networks

Supply status meaning

In stock or short-notice availability

Data Rate425Gbps
Max Data Rate8x53.125Gbps
Form Factorsingle-port QSFP-DD
StandardSR4
Lanes8
Rate per Lane53.125Gbps PAM4
Reach40m@OM3 / 70m@OM4
MediaMMF
Fiber TypeOM3 / OM4
ConnectorMPO-12/APC
Connector PolishAPC
Wavelength850nm
Max Power8W
Operating Temperature0 to 70C (32 to 158F)
Optical Modulation4x100G-PAM4
Electrical Modulation8x50G-PAM4
FECInbuilt FEC: Yes
IEEE ComplianceIEEE 802.3
MSA ComplianceQSFP-DD MSA
ProtocolsQSFP-DD MSA,IEEE 802.3,CMIS5.2
Host Interfacesingle-port QSFP-DD
Warranty5

Four bulk tiers — the larger the volume, the better the discount. Actual pricing is confirmed by RFQ based on quantity, customer tier and lead time; there is no single-unit retail.

PackageQuantityVolume discountBest for
Starter Pack 100 pcs Base bulk price Trial order / small channel Request Quote
Growth Pack 500 pcs Save ~5% vs. Starter Reseller / regular supply Request Quote
Project Pack Popular 1000 pcs Save ~10% vs. Starter AI data center project Request Quote
Strategic Pack 2000 pcs Save ~15% vs. Starter Annual / channel agreement Request Quote
Custom bulk order 2000+ pcs Negotiated offline Annual / strategic supply Contact Sales

Ask a compatibility question

Need this model to match a specific switch, NIC or OEM coding? Send us the platform and we'll confirm compatibility and coding options.

  • Compatible coding for major switch / NIC platforms on request
  • Alternative model recommendations
  • Breakout and cabling guidance

Supply & compliance FAQ

How do the proposed FCC rules on optical transceivers affect availability?

The FCC rulemaking reported in August 2026 is still a draft. As reported, it would apply to new model authorizations, while models already deployed and shipping would continue to be supplied. Current PhoScale shipments are unaffected, and we hold inventory in our US warehouse. We track the rulemaking closely and publish updates on our Insights page.

Can you provide compliance documentation for your transceivers?

Yes. Every SKU ships with per-unit test reports, and compliance documentation (FCC, FDA laser, RoHS) is available on request as part of our ongoing compliance program.

How do you protect buyers against supply-chain disruption?

Three ways: US-warehouse stock for immediate needs, multi-source manufacturing across tier-one Asian production partners, and allocation planning for project and annual-supply customers. See our Supply Assurance page for details.

What lead times should we plan for on 800G and 1.6T optics?

In-stock models ship from our US warehouse immediately. For volume orders, typical lead times are 2–6 weeks depending on model and quantity — submit an RFQ for a confirmed date against current allocation.

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