Optoacoustic generation and electrical detection of subnanosecond acoustic pulses

The optoacoustic generation and electrical detection of acoustic pulses of about 0.5-ns duration in quartz and in several polymer materials is demonstrated. The ultrasonic pulses are generated by thermoelastic effects and/or ablation due to absorption of 70-ps laser-light pulses in an opaque coupling layer deposited on one of the sample surfaces. Detection of the acoustic pulses is possible by using electrically charged, piezoelectric, or biased samples which yield electrode signals upon transit of the pulses. The acoustic pulses have also have been used to measure ultrasonic velocity and attenuation in various materials.