Design of a remote and integrated Sagnac interferometer that can generate narrowband guided wave through the use of laser and effective optics to detect defects occurred in plates

•An optical design is proposed to generate GW for inspecting of aluminum plate.•It adopts common-path design and can generate tunable GW signals on plate.•GW generated centered at desired and predicted frequency.•GW signals generated are of higher SNR than the previous reported IOMZ.