Multipoint Fiber-Optic Ultrasonic Actuator Based on Bent Fiber Structures Along a Single Fiber

All-fiber optic ultrasonic testing technology has attracted considerable attention because of its applications in structural health monitoring, medical diagnosis, and material characterization. Fiber-optic ultrasonic actuator is the key component in all-fiber optic ultrasonic testing. In this paper, we demonstrated a multipoint fiber optic ultrasonic actuator by linking cascade bent fiber structures along a fiber. A bent fiber radiates a part of core energy into fiber cladding for photoacoustic conversion; this energy can be controlled by adjusting the fiber's bend radius. Using such characteristics, a multipoint fiber optic ultrasonic actuator with balanced signal strength was prepared by linking cascade bent fiber structures with reasonable coupling ratios along a fiber. Our inexpensive and easy-to-fabricate actuator can generate balanced ultrasonic signal strength and has potential applications in fiber optic ultrasonic testing technology.