Design Of Transducer In PbMoO₄ Acousto-optic Device And Its Frequency Property

Acousto-optic device which had been quickly developed since 1960s, is a common name of all appliances used to control the frequency, direction and intensity of light beams based on the interaction of ultrasonic and lightwave in certain media. Acousto-optic device has wide applications for military and civilian use in many areas. To enhance the performance of acousto-optic device, many countries invested much manpower and resources to research the interaction characteristics of light and sound. The research is mainly focused on the interaction theory of sound and light, the development of high-performance materials used as interaction madia, the development of high-frequency bulk wave and surface wave piezoelectric transducer in its theory and technology.The performance of acousto-optic device is mostly decided by its transducer bandwidth and Bragg bandwidth. Based on the introduction of acousto-optic interaction theory, this paper provide a common method of calculating the input electrical impedance and the bandwidth of piezoelectric transducer in acousto-optic device in terms of the principle of Mason equivalent circuit, according to frequency property of transducer loss, decide the layer material, thickness and input electrical impedance performance of 4-layer and 5-layer transducer who has large bandwidth in 36°Y-cut LiNbO3/ PbMoO4 (LN/PM for short in future) acousto-optic device. To enhance the performance of transducer and minimize the technical difficulties, an external circuit and its component value are supposed according to network matching principle and matrix calculating method to match the 5-layer transducer in PM acousto-optic device, to some extent make up the transducer loss and enlarge the transducer bandwidth. Finally, an adjusted structure of tranducer after inserting external matching network is provided, which is favorable for reducing the production cost with little impact of transducer bandwidth.