QSFP-DD package is favored by 400G due to its advantages of high speed, small size, and pluggable, and 400G QSFP-DD optical module has become one of the most popular optical modules when interconnecting next-generation data center networks. With the standardization of 400G, major vendors, and suppliers have developed different types of 400G QSFP-DD optical modules.
Types of 400G QSFP-DD Optical Modules
The types of 400G QSFP-DD optical transceiver modules include 400G QSFP-DD SR8, 400G QSFP-DD DR4, 400G QSFP-DD FR4, 400G QSFP-DD LR4, 400G QSFP-DD LR8 and so on. See the table below for details.
The “SR” refers to the use of multi-mode fiber to achieve a transmission distance of 70 meters, 100 meters, or 150 meters. “8” means the module has 8 fiber channels. “DR” refers to a 500m transmission distance using single-mode fiber. “4” means the module has 4 fiber channels. “XDR4” is an extended version of “DR4”. “FR” refers to a 2 km transmission distance using single-mode fiber. “LR” refers to a 10 km transmission distance using single-mode fiber.
Connection Solutions for Regular 400G QSFP-DD Optical Modules
400G QSFP-DD SR8
As can be seen above, the 400G QSFP-DD SR8 optical module can achieve 400G transmission through the multi-mode fiber with a maximum distance of up to 100 meters (OM4). Therefore, the 400G QSFP-DD SR8 optical module is more suitable for short-distance interconnection or multi-channel data communication. The common connection scheme is as follows: 400G interconnection: 400G QSFP-DD SR8 optical transceiver module at both ends can be connected by MPO/MTP-16 fiber patch cable to achieve 400G transmission.
Multi-channel data communication
①400G QSFP-DD SR8 optical module can be connected to the 200G SR4 optical transceiver module at the opposite end through a MPO/MTP-16 to 2*MPO/MTP-8 fiber patch cable.
②400G QSFP-DD SR8 optical module can be connected to the 50G SF56 optical module at the opposite end through a 16-core MPO/MTP to 8*LC duplex branch fiber patch cable.
400G QSFP-DD DR4
The 400G QSFP-DD DR4 optical module is suitable for interconnecting 400G and 100G over short distances because of its transmission distance of up to 500 meters and its support for interconnecting with 100G DR optical modules. 400G QSFP-DD DR4 optical transceiver module can be connected to 100G DR optical modules at the opposite end through an MPO-12 to 4*LC duplex branch fiber patch cable.
400G QSFP-DD XDR4/DR4+
The 400G QSFP-DD XDR4 and 400G QSFP-DD DR4+ optical module is an extended version of the 400G QSFP-DD DR4 optical module, which can be interconnected with the 100G FR optical module. Therefore, this module can be connected to the 100G FR optical transceiver module at the opposite end through an MPO-12 to 4*LC duplex branch fiber patch cable.
400G QSFP-DD FR4
The 400G QSFP-DD FR4 optical transceiver module is suitable for 400G interconnection because it uses four CWDM wavelength uncooled EML lasers with PAM4 modulation based on single-wave transmission at rates up to 106.25Gbps. Two 400G QSFP-DD FR4 optical modules can be interconnected through LC duplex fiber patch cables for 400G interconnection.
400G QSFP-DD FR8
400G QSFP-DD FR8 optical module (400G QSFP-DD 2FR4 optical module) is a 2*200G module. Different from the 400G QSFP-DD FR4 optical module, the 400G QSFP-DD FR8 optical module adopts 50G PAM4 modulation technology and provides eight fiber channels, which is more suitable for multi-channel data communication. Normally, the 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 fiber patch cable.