Since the mainstream in 2025 will still be traditional optical modules, we will analyze and discuss the industry chain of traditional pluggable optical communication modules. The industry chain can be divided into three parts: upstream component supply, midstream module manufacturing, and downstream end-use applications, etc. Important components include: (1). Microcontrollers (MCUs), Digital Signal Processors (DSPs), Clock and Data Recovery (CDRs), Laser Source Drivers (LDDs), and other chips, (2). Optoelectronic components such as laser diodes (LDs) and photodetectors (PDs), (3). Optical signal emitter (TOSA), (4). Optical Signal Receiver (ROSA), and the technological development of each component is summarized as follows.