Laser Doppler Vibrometry Measurements of Conversion of Surface Guided Waves to Optical Fiber Modes

摘要

Previous studies demonstrated the coupling of Lamb waves to guided traveling waves in an optical fiber through an adhesive bond. However, the mode conversion at the specific coupling location has not been experimentally verified. This work measures the mode conversion of ultrasonic waves through an adhesive bond, implementing a high-resolution 3-dimensional laser Doppler vibrometer. Specifically, the propagation of surface guided S-0 and A(0) modes in a thin plate and their conversion into L-01 and F-11 modes in an optical fiber are successfully verified. In addition, the conversion of a shear-horizontal mode in the plate into an orthogonal F-11 mode is also identified.