The 400GBASE-SR4.2 (BiDi) Standard was announced by the 400G Bidirectional (BiDi) MSA (Multisource Agreement) Group in the year 2018. The specification will be named 400G-BD4.2, to identify the bidirectional use of four lasers each of two colors. Using the 400G-BD4.2 specification, two transceivers communicate over lengths up to 70 meters (OM3 MMF Multimode fiber), 100m (OM4 MMF) and 150m (OM5 MMF).
The 400G-BD4.2 modules comply with the requirements of the standard and have the following common features: eight optical transmitters and eight optical receivers in a bi-directional optical configuration (four of the transmitters using a wavelength range of 844nm to 863nm, λ1, and four of the transmitters using a wavelength range of 900nm to 918nm, λ2), a signal detect for each optical receiver and a twelve channel MPO fiber optic connector (only eight fibers total are required) using multimode optical fiber.
400G-BD4.2 Illustrative Power Budget
|Parameter||OM3 MMF||OM4 MMF||OM5 MMF|
|Effective Modal Bandwidth at 850nm (MHZ KM)||2000||4700||4700|
|Effective Modal Bandwidth at 918nm (MHZ KM)||1210||1850||2890|
|Power Budget (For max TDECQ) (dB)||6.6||6.6||6.6|
|Operating Distance (m)||70||100||150|
|Channel Insertion Loss (dB)||1.8||1.9||2.0|
|Allocation for Penalties (for max TDECQ) (dB)||4.6||4.6||4.6|
|Additional Insertion Loss Allowed (dB)||0.2||0.1||0|
- Per IEC 60793-2-10.
- Per draft IEC 60793-2-10 (subject to confirmation by TIA and IEC).
- The channel insertion loss is calculated using the maximum distance specified and the cabled optical fiber attenuation of 3.5 dB/km at 850 nm, plus an allocation of 1.5 dB for connection and splice loss (as given in IEEE P802.3cdTM/D3.4 Clause 18.104.22.168.1).
- Link penalties are used for link budget calculations. They are not requirements and are not meant to be tested.
400G-BD4.2 Lane Ordering for MPO Optical Connector
The MSA group is dedicated to defining optical interface specifications based on a dual wavelength BiDi transmission technology, which enables a reduction in the fiber count relative to other solutions.