ETSC’s OM3680SX200 is a parallel 400GE Quad Small Form Factor Pluggable double density (QSFP-DD) SR8 optical module designed for optical communication applications. The optical module uses a 4- level pulse amplitude modulation (PAM4) format. The optical module provides point-to-point 400 Gigabit Ethernet links over eight pairs of multimode fiber, with a reach of up to 100 m for OM4 (MMF) and 70 m for OM3 (MMF). It is compliant with QSFP-DD MSA standard and IEEE 802.3cm 400GBASE-SR8 standard and IEEE 802.3bs 400GAUI-8 standard. Digital diagnostics functions are available via the I2C interface, as specified by the QSFP-DD MSA.