Use an optical power meter to check whether the transmit optical power of the optical module is normal. Optical modules (SFP, SFP+, QSFP, QSFP28, etc. ) are designed for high reliability in modern networks. Yet in real-world deployments, many data centers, ISPs, and enterprise networks still experience unexpected link failures after installation. These failures are rarely caused by “defective. An optical module is a critical component in modern optical communication systems, directly affecting transmission stability, network reliability, and operational efficiency. However, during installation and daily operation, various issues may arise. This article. A hyperscale network operator recently discovered that 12% of their 400G DR4 modules—all from an AVL-approved supplier—failed within 90 days of deployment. Root cause analysis traced the failures not to a design flaw, but to a contract manufacturer switching laser bonding adhesive without. ESD is the abbreviation of ElectroStatic Discharge, that is, "electrostatic discharge", which is a very fast process whose rise time can be less than 1ns (one billionth of a second) or even hundreds of ps (1ps=one billionth of a second).