QSFP-DD packages are favoured for 400G due to their high speed, small size, and pluggability, and 400G QSFP-DD optical modules have become one of the most popular optical modules when interconnecting next-generation data centre networks. With the standardisation of 400G, major vendors and suppliers have developed different types of 400G QSFP-DD optical modules.

A 400GBASE-SR8 QSFP-DD optical module that should be hot in the market now has a transmission distance of up to 100m over multimode fibre, and is used in 400G Ethernet, high-performance data centre and cloud networks, supporting 400G-400G direct connect, 400G-2*200G interconnect (using 16-core MTP/MPO to 2*8-core MTP/MPO branch). jumpers to connect 400G QSFP-DD SR8 and two 200G QSFP56 SR4s) and 400G-8*50G interconnect (16-core MTP/MPO to 8*LC duplex jumpers to connect 400G QSFP-DD SR8 and eight 50G SR modules).

400G QSFP-DD series optical modules can be applied to the equipment:

Cisco HW H3C Juniper Arista Brocade Dell Extreme Generic Intel Finisar Ciena Avago Mikrotik Allied Telesis IBM F5 Networks Palo Alto Networks Fortinet Check Point Chelsio Edge-Core D-Link Alcatel-Lucent

400G QSFP-DD series optical module Type:

• QSFP-DD-400G-SR8-100M

• QSFP-DD-400G-LR4-10KM

• QSFP-DD-400G-FR4-2KM

• QSFP-DD-400G-DR4-500M

• QSFP-DD-400G-FR8 -2KM

"SR" refers to the use of multimode fibre optics to achieve transmission distances of 70m, 100m or 150m." The "8" refers to the module having 8 fibre channels." DR" refers to the use of single mode fibre to achieve a transmission distance of 500 m." 4" means that the module has 4 fibre channels." FR "refers to a transmission distance of 2 km using single mode fibre." LR" refers to a 10 km transmission distance using single-mode fibre.

Connection scheme of conventional 400G QSFP-DD optical module

400G QSFP-DD SR8

From the above, we can see that 400G QSFP-DD SR8 optical module can achieve 400G transmission over multimode fibre up to 100m (OM4). Therefore, 400G QSFP-DD SR8 optical module is more suitable for short distance interconnection or multi-channel data communication. Common connection schemes are as follows: 400G interconnection: 400G QSFP-DD SR8 optical transceiver module can be connected at both ends by MPO/MTP-16 fibre optic patch cord to achieve 400G transmission.

Multi-Channel Data Communication

The 400G QSFP-DD SR8 optical module can be connected to the 200G SR4 optical transceiver module at the other end via a MPO/MTP-16 to 2*MPO/MTP-8 fibre optic patch cable.

The 400G QSFP-DD SR8 Optical Module can be connected to the 50G SF56 Optical Module at the other end via a 16-core MPO/MTP to 8*LC duplex branch fibre patch cable.

400G QSFP-DD DR4

The 400G QSFP-DD DR4 optical module is suitable for short-distance interconnection between 400G and 100G because it has a transmission distance of up to 500 m and supports interconnection with 100G DR optical modules.The 400G QSFP-DD DR4 optical transceiver module can be connected to the other end of the 100G DR optical module via a duplex branching fibre optic patch cord with MPO-12 to 4*LC.

400G QSFP-DD FR4

The 400G QSFP-DD FR4 optical transceiver module is suitable for 400G interconnections because it uses four uncooled EML lasers at CWDM wavelengths based on PAM4 modulation for single-wave transmission at rates up to 106.25 Gbps. two 400G QSFP-DD FR4 optical modules can be interconnected via LC duplex fibre patch cords for 400G interconnections.

400G QSFP-DD FR8

400G QSFP-DD FR8 optical module (400G QSFP-DD 2FR4 optical module) is a kind of 2*200G module. Different from 400G QSFP-DD FR4 optical module, 400G QSFP-DD FR8 optical module adopts 50G PAM4 modulation technology and provides 8 fibre channels, which is more suitable for multi-channel data communication. Normally, 400G QSFP-DD FR8 optical module can be connected to the opposite end 200G FR4 optical module through 2*CS to 2*LC duplex branch fibre patchcord.

QSFP-DD 400G SR8 Product Parameters

QSFP-DD 400G LR4 Product Parameters

QSFP-DD 400G FR4 Product Parameters

QSFP-DD 400G DR4 Product Parameters