SPQ-4E-FR-CDFB Source Photonics Compatible 400GBASE-FR4 QSFP-DD Transceiver

EdgeOptic's SPQ-4E-FR-CDFB compatible is a Source Photonics-coded 400GBASE-FR4 QSFP-DD transceiver, with the same 2 km duplex single-mode reach, the same LC/UPC connector pair, and the same optical and electrical envelope as the original Source Photonics part. The CDFB ships against IEEE 802.3cu and the 100G Lambda MSA 400G-FR4 specification.

Four CWDM wavelengths at 1271, 1291, 1311, and 1331 nm multiplex onto a single duplex LC pair. PAM4 modulation at 53.125 GBaud per lane delivers 400 Gb/s aggregate throughput across the optical interface. EML transmitters drive each wavelength channel; PIN photodiode receivers handle the inbound side. TX power is -3.3 to +3.5 dBm per lane, RX sensitivity is -7.3 dBm. The 4 dB optical link budget covers a 2 km OS2 span with margin for patch panels and splices in normal data center cabling. Maximum power consumption 10 W. The module ships with a 400GAUI-4 host electrical interface per IEEE 802.3cu, so the four host SerDes lanes run at 106.25 Gb/s PAM4 each into the chassis ASIC. Full 400GBASE-FR4 specifications cover the rest.

Source Photonics also catalogs a follow-on variant, the SPQ-4E-FR-CDFC. Both share the same 400GBASE-FR4 standard and the same LC duplex interface; the B versus C suffix indicates a manufacturing revision. Verify the exact part number from the installed transceiver label or the chassis inventory before ordering, since both variants exist in the field on different deployment generations.

The SPQ-4E-FR-CDFB is an OEM transceiver shipped into 400G switching and routing platforms as a factory-installed component. Source Photonics does not publish a per-chassis compatibility matrix, since the same module appears across multiple switch vendors with vendor-coded EEPROM. EdgeOptic programs the EEPROM for Cisco, Arista, Juniper, HPE Aruba, or other targets at build time, so the same FR4 module can replace a failed Source Photonics part across mixed-vendor sites. Specify the chassis vendor and software release on the order, and verify host compatibility against the platform vendor's transceiver matrix for the specific NOS version.

Conforms to IEEE 802.3cu-2021, 100G Lambda MSA 400G-FR4, QSFP-DD MSA HW Rev 5.1, and CMIS Rev 4.0. CMIS exposes per-lane TX and RX optical power, module case temperature, supply voltage, and laser bias current over standard I2C, so DOM integrates with existing chassis monitoring through the host NOS diagnostic commands. KP4 RS-FEC, RS(544,514), is required from the host ASIC at 400G to meet the PAM4 BER target; the module itself does not provide FEC. Class 1 laser safety per IEC 60825-1 and FDA, CE and RoHS certified, 0 to 70 °C commercial operating temperature.

FR4 fits 400G data center interconnect, leaf-spine uplinks, and aggregation above a 100G leaf layer. Duplex LC patching keeps structured cabling simple where the existing single-mode plant already runs LC, the alternative to MPO-12 parallel optics on DR4. A 2 km reach covers most intra-campus and metro-edge runs.

Backed by 15+ years of EdgeOptic compatibility engineering across vendor optical platforms. Made to order with a 2-week lead time and lifetime warranty included. For volume pricing or platform-specific EEPROM coding requests, contact our sales team.