An ultrasonic hydrophone based on a dual polarization distributed Bragg reflector (DBR) fiber laser is described, and its application to detecting the vector medical ultrasound is demonstrated. The principle of the hydrophone is based on the detection of output beat frequency signal modulated by ultrasound. The amplitude, frequency and orientation of the ultrasound can be determined by the using the upper and lower sideband frequency. It has been found that the hydrophone has an orientation recognizable ability which the piezoelectric ultrasonic immersion transducer doesn’t have. It suggests that the type of hydrophone can provide an alternative to piezoelectric hydrophone technology.
Distributed Bragg Reflector (DBR) polarimetric optical fiber laser sensors have been attracting great interests due to harsh environment capability and high signal-to-noise ratio .We demonstrate directional force measurement technology using dual-polarization DBR optical fiber laser as a sensor. The influences of external force (bending, current and ultrasonic signal) could be analyzed by inducing a DFB polarimetric laser sensor to detect the beating signals shifts when the cavity is perturbed. We present the analysis of sensing mechanism on the DBR geometric construction and demodulation of directional information by separating the dual orthogonal polarization modes. With loading angles at 35°, 45°, 55°with 10° interval, the DBR laser sensor has shown orientation recognization ability corresponding to beating signals shifts, offering a potential for vector force directional detection.