Upstream players provide core optical and electrical components, including optical materials, laser chips, photodetectors, high-speed signal processing chips (DSP/SerDes/Driver), and integrated components such as silicon photonics PICs and optical engines. In traditional passive optical network (PON) neighboring, optical network units (ONUs) cannot communicate directly but through optical line terminals, resulting in propagation delays, security hazards and unnecessary use of upstream and downstream bandwidth. Midstream players—optical transceiver. ITU-T is promoting the commercialization of coherent transceivers that use phase modulation, such as DP-QPSK, for long-distance transmission, as well as research into methods for modulating a greater number of values (16 QAM and 32 QAM) in order to increase the transmission capacity without. Evolving towards the 2030 optical communications network system and architecture is a key issue facing the optical communications industry and requires viable technical options for building future-oriented and novel optical communications network systems. Optical networks form infrastructure that. An optical transmission system is a part of the transport layer in network. It consists of transmitter, receiver, optical amplifiers, dcm, wdm and transmission fiber.