Structural health monitoring is implemented to monitor the structural integrity of the structure. The guided wave technique is utilized to investigate the health status of the aluminum plate. The wave is actuated at 6 kHz using a PZT actuator and recorded using the optical fiber sensor. The wave is recorded on the intact plate at 2- and 4-mm thickness. Three different defect depths are introduced on the 4 mm plate's thickness, and three different defect widths are introduced on the 2 mm plate's thickness. The recorded waves measured on the 1/3, 2/3, and 3/3 of the defect depths show a wave amplitude decrement of 72%, 84%, and 88%, respectively, compared to the wave amplitude of the intact plate. For the defect widths of 1, 1.5, and 2 cm, the decrement of the wave amplitude is 83%, 87%, and 94%, respectively. The severity of the structure can be monitored by the decrement of the wave amplitude. The finding shows that the guided wave approach is able to be utilized as one of the promising techniques to monitor the structural integrity of the metallic structure. © 2024 Wiley-VCH GmbH.