QSFP28 is the main form factor for 100G optical modules. It features low power consumption, high port density, compact size, and cost efficiency. This article reviews QSFP28 module types and key WDM technologies like CWDM and DWDM. A 100G optical module converts electrical signals to optical signals and vice versa, enabling high-speed communication between servers, switches, and backbone networks. This robust expansion is primarily driven by escalating demand for high-speed data transmission in. 1) Its second-generation 100G QSFP28 ZR4 80KM optical module adopts four-channel 28G NRZ wavelength division multiplexing technology, achieving a maximum transmission distance of 80km while keeping power consumption below 5.