400G OSFP-RHS SR4 is a cost effective module with high performance, which is optimized for datacenter, supporting data-rate of 8 × 26.5625 GBd PAM4. Its transmission distance is up to 100m on OM4 MMF. The module mainly consists of two parts: the transmitter part and the receiver part. The transmitter part consists of 850nm VCSEL array and driver. The receiver part consists of trans

-impedance amplifier (TIA) and PIN photodiode array. The high-speed electrical interface is based on low-voltage logic, with nominal 100 ohm differential impedance, AC coupled in the module. Users can access a series of registers in transceiver to access monitoring and configuration data through two wire serial interface. This interface uses a single address, A0h, with a memory map divided into a lower and upper area. Basic digital diagnostic (DD) data is held in the lower area while specific data is held in a series of tables in the high memory area.