Introducing the Huawei QSFP-DD-400G-ZR, a high-performance 400GBase-ZR optical module. This single module, operating at a wavelength of 1547. 715 NM, is designed for Dense Wavelength Division Multiplexing (DWDM) to support data transmission up to 40 km. Optical modules are optoelectronic devices that perform photoelectric and electro-optic conversions. Optical modules are classified by their packaging forms, with common types including SFP, SFP+, SFP28, QSFP+, QSFP28, QSFP56, QSFP-DD, QSFP112, and. When this type of optical module is used to interconnect with WDM equipment, the protection switching time of WDM client-side 1+1 protection is greater than 50 ms. When the board is used for 40 km transmission, it must be interconnected with a Huawei optical module of the same model. With an LC connector type, it ensures.