This product is a 400Gb/s QSFP112 optical module designed for 0. 5Km optical communication applications. The module converts 4 channels of 100Gb/s (PAM4) electrical input data to 4 channels of parallel optical signals, each capable of 100Gb/s operation for an aggregate data rate of. This chapter describes the 400G Digital Coherent QSFP-DD optical modules and their supported configurations. Coherent optics uses phase and amplitude to encode data, unlike PAM4 optics (Pulse amplitude modulation) which only uses amplitude. This allows coherent optics to be more resistant to noise. First, let's clarify what VR, SR, DR, FR, LR, ER, and ZR stand for, so that we can understand and identify them: VR (Very Short Range): Transmission distance usually 0~100 meters, using multimode fiber for short data center connections. Nokia coherent routing utilizes a new generation of digital coherent optics (DCOs) equipped in router interface ports to n the router-pluggable QSFP-DD format. Developed by the Optical Internetworking Forum (OIF) and released in March 2020, 400ZR is. 2. With a transmission rate of up to 400 Gbps, 400G transceivers offer double the capacity of their predecessor (200G transceivers).