Unidirectional and tunable acoustic diode made by asymmetric double layer metallic grating with periodical structure

This paper theoretically investigates unidirectional and tunable acoustic transmission in a structure of double layer metallic grating immersed in water. Though numerical simulations, we find that the asymmetric acoustic transmission can be achieved by changing the width and the thickness of the double layer metallic gratings. We also find that the contrast transmission ratio of unidirectional transmission is highly influenced by the ratio of the thickness h1/h2. And further study indicates that the working frequency range of the asymmetric transmission can be easily controlled by adjusting the location of the double layer metallic gratings. This constructed acoustic system shows many potential applications of medical ultrasound diagnosis and related fields.