Acoustic emission in prestressed composite panels has been detected using embedded single mode optical fibers. Static loading of the composite matrix produces acoustic emission events, pulsed ultrasonic waves, which mechanically modulate the embedded fiber geometry and phase modulate the transmitted optical field. This modulation is detected by optical interferometry and Fourier optical processing techniques to produce an electronic signal proportional to acoustic field amplitude integrated along the length of the fiber in the specimen. NASA Tech Brief. 8.5" x 11"