Recent years have seen the evolution towards the 5G, Internet of Things (IoT), and cloud computing, increasing pressure on data centers to ramp up both network capacity to 400G and driving providers to search for new solutions to achieve their 400G Data Center Interconnects (DCIs). 400G QSFP-DD optical transceiver module is becoming one of the most popular cutting-edge 400G DCI solutions. This article will provide a basic understanding of QSFP-DD optical transceiver modules.

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Recent years have seen the evolution towards the 5G, Internet of Things (IoT), and cloud computing,
increasing pressure on data centers to ramp up both network capacity to 400G and driving providers to
search for new solutions to achieve their 400G Data Center Interconnects (DCIs). 400G QSFP-DD optical
transceiver module is becoming one of the most popular cutting-edge 400G DCI solutions. This article
will provide a basic understanding of QSFP-DD optical transceiver modules.
What is the QSFP-DD Optical Transceiver Module?
Quad small form-factor pluggable-double density (QSFP-DD) is designed with eight lanes that
operate at up to 25 Gbps via NRZ modulation or 50 Gbps via PAM4 modulation. It supports data
rates of 200 Gbps or 400 Gbps and doubles the density. QSFP-DD is backward compatible with
current 40G and 100G QSFPs. It is compliant with IEEE802.3bs and QSFP-DD MSA standards.

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QSFP-DD is available in single-mode (SM) and multi-mode (MM) fiber optic cables and includes
digital diagnostics monitoring (DDM) to monitor parameters such as power, temperature, and
voltage.
Types of 400G QSFP-DD Optical Transceiver Module
1. 400G SR8 QSFP-DD
400G SR8 QSFP-DD optical transceiver module is suitable for short-distance interconnection or
multi-channel data communication. The transmission rate is up to 425Gbps, and the central
wavelength is 850nm. The transmission distance is up to 70m or 100m through multi-mode OM3
and OM4 fiber.
2. 400G DR4 QSFP-DD
400G DR4 QSFP-DD optical transceiver module achieves the transmission over single-mode fiber
(SMF) with an MPO-12 connector. It supports a max transmission distance of 500m on SMF.
3. 400G FR4 QSFP-DD
400G FR4 QSFP-DD optical transceiver module supports link lengths of up to 2km SMF with a
duplex LC connector. It uses wavelength division multiplexing(CWDM ) technology, eight channels

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of 53Gbps PAM4 signals on the electrical side, and four channels of 106Gbps PAM4 signals on the
optical side, which is twice the rate of the electrical side.
4. 400G LR4 QSFP-DD
400G LR4 QSFP-DD optical transceiver module is designed with a built-in Gearbox chip that
multiplexes the two channels' electrical input data into a single-channel outputs signal and then
modulates it to the optical receiver end. The digital signal processor (DSP) basis gearbox converts
eight channels of 25GBaud PAM4 signals into four channels of 50GBaud (PAM4) over an SMF
cable with duplex LC connectors. It supports a transmission distance of up to 10km.
5. 400G LR8 QSFP-DD
The 400GBASE-LR8 optical transceiver module supports link lengths of up to 10km over a
standard pair of G.652 SMF with duplex LC connectors.
6. 400G ER8 QSFP-DD
The 400G ER8 QSFP-DD optical transceiver module supports link lengths of up to 40km over a
standard pair of G.652 SMF with duplex LC connectors.
7. 400G ER4 QSFP-DD
400G ER4 QSFP-DD optical transceiver module supports link lengths of up to 40km over a
standard pair of G.652 SMF with duplex LC connectors. It has only four wavelengths for 4 LAN
WDM channels 1295.56/1300.05/1304.58/1309.14nm.
Advantages of 400G QSFP-DD Optical Transceiver Module
Backward compatibility: Allowing the QSFP-DD to support existing QSFP modules (QSFP+,
QSFP28, QSFP56, etc.). It provides flexibility for end-users and system designers.
Adopting the 2x1 stacked integrated cage/connector to support the one-high cage connector

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and two-high stack cage connector system.
SMT connector and 1xN cage design: Enable thermal support of at least 12W per module. The
higher thermal reduces the requirement for heat dissipation capabilities of transceivers, thus
reducing some unnecessary costs.
ASIC design: Supporting multiple interface rates and fully backward compatible with QSFP+ and
QSFP28 modules, thus reducing port and equipment deployment costs.
Applications
400G QSFP-DD optical transceiver module is used in 400G Ethernet, data centers,
telecommunications networks, cloud networks, Infiniband interconnects, high-performance
computing networks, 5G, 4K video, IoT, etc.
Conclusion
400G QSFP-DD optical transceiver module offers high speed, performance, scalability, and low
power in 400G Ethernet. Sun Telecom specializes in providing one-stop total fiber optic solutions
for all fiber optic application industries worldwide. Contact us if any needs.