QSFP-DD stands for Quad Small Form Factor Pluggable – Double Density. Defined by the QSFP-DD MSA group, it is a high-speed, hot-pluggable form factor crucial for high-density networking in the optical communication industry. As the optimal form factor for 400G optical transceivers, QSFP-DD enables data centers to scale up cloud capacity effectively and on demand.
QSFP-DD is both backward and forward compatible with QSFP ports, including support for legacy QSFP28 optical transceivers, AOC/DAC cables, and more. The QSFP-DD connector supports 8 electrical channels, each operating at either 25Gb/s NRZ or 50Gb/s PAM4, delivering total electrical bandwidths of 200Gb/s or 400Gb/s. One switch slot with QSFP-DD ports can deliver up to 14.4Tb/s of aggregated bandwidth.
The 400G DR4 optical transceiver is designed for 400G Ethernet data center interconnects using the QSFP-DD form factor. On the transmit side, the DR4 transceiver converts 8 channels of 50Gb/s (PAM4) electrical signals into 4 parallel optical channels, each running at 100Gb/s, resulting in a total optical bandwidth of 400Gbps. On the receive side, the module converts 4x100Gb/s optical signals back into 8x50Gb/s electrical outputs.
The 400G QSFP-DD DR4 optical transceiver uses an MPO-12 connector for transmission over SMF (single-mode fiber) and typically supports a reach of up to 500 meters at a central wavelength of 1310nm. Designed according to the QSFP-DD MSA specification, this module supports full digital diagnostics.
The 400GBASE-FR4 optical transceiver is a hot-pluggable module operating at 400Gbps and using the QSFP-DD form factor. The module integrates 4 independent optical channels operating at 100Gbps each over CWDM4 wavelengths (1271/1291/1311/1331nm). It uses 4 uncooled 100Gbps CWDM EML lasers combined with a multiplexer for optical transmission.
Featuring a duplex LC connector, the 400G FR4 transceiver supports up to 2 kilometers over single-mode fiber (SMF). It is compliant with the 100G Lambda MSA specification and QSFP-DD MSA standards.
The 400GBASE-LR4 optical transceiver adopts an integrated Gearbox chip design that multiplexes two channels of electrical input data into a single output, then modulates it for optical transmission. The DSP-based gearbox converts 8x25GBaud PAM4 electrical channels into 4x50GBaud PAM4 optical signals transmitted over SMF using a duplex LC interface.
This transceiver features built-in FEC and real-time digital diagnostics and supports transmission distances up to 10 kilometers. It defines a 400Gb/s PHY operating at CWDM wavelengths of 1271, 1291, 1311, and 1331nm. Gearlink’s 400G LR4 optical transceivers are fully compatible with Huawei and H3C equivalents, offering excellent interoperability.
The 400G SR8 optical transceiver complies with IEEE 802.3bs and QSFP-DD MSA standards. It offers 8 parallel transmitter and receiver channels, each supporting 53.125Gbps (PAM4), delivering a total bandwidth of 400Gbps over OM3 multimode fiber (MMF) with an MTP/MPO-16 connector.
Each of the 8 channels operates at a central wavelength of 850nm and supports transmission distances up to 100 meters. Similar to the DR4, FR4, and LR4 modules, the 400G SR8 is widely used in short-reach intra-data center applications.
Today, 400G optical transceivers have been widely deployed in domestic supercomputing and AI computing centers. Gearlink Technology’s 400G optical transceivers have been shipped in volume with stable performance. We welcome inquiries and look forward to providing reliable optical interconnect solutions.
