Amplitude‐Phase Dual‐Channel Encrypted Acoustic Meta‐Holograms

Abstract

Abstract Encrypted acoustic meta‐holograms have potential applications in confidential acoustic information communication, noise control, acoustic cloaking, acoustic illusion, etc. Conventional encrypted optical and acoustic meta‐holograms only focus on the encrypted hologram in a single channel, viz. modulating spatial amplitude to project a holographic image. Here, the concept of an amplitude‐phase dual‐channel encrypted acoustic meta‐hologram (DrEAM) is proposed, capable of generating, encrypting, and decrypting both amplitude and phase holographic images. This unique concept of “phase holographic image” introduces a new degree of freedom for meta‐holograms, leading to dual‐channel encrypted acoustic holography. Acoustic metasurface with simultaneous amplitude and phase modulations is employed to realize this dual‐channel encryption. The findings may offer the possibility to increase the capacity of the encrypted acoustic meta‐holograms, which can lead to practical applications in, for example, multi‐channel acoustic field communications, complex noise control, and acoustic illusions.