Acoustic diode realized by asymmetric filter

Abstract

Devices of one-way transport for acoustic waves are called acoustic diode. They are able to promote the advancement of noise isolation, acoustic communication, acoustic signal processing. A lot of designs of acoustic diodes based on various mechanisms have been given. However, most designs have problems of one kind or another, such as low efficiency, instability, bulky volume, complex structure, frequency change, waveform distortion and so on. An asymmetric acoustic filter with only three layers is proposed in this work. The total length of the acoustic diode is less than the half wavelength. Its backward transmission is almost completely stopped. For the forward transmission, the amplitude of the transmitted wave is almost proportional to the driving voltage. This characteristic is better than its electronic counterpart which is often annoyed by the unavoidable nonlinearity at high driving voltage. A simple, compact, stable, broadband, frequency-preserved, highly efficient, linear acoustic diode is realized.