"可调透射的声学超表面：连续调节传输波前的物理评价应用"

版权申诉

5星 · 超过95%的资源 62 浏览量更新于2024-04-18 收藏 8.36MB PDF 举报

The study presented in the article titled "Continuously Tunable Acoustic Metasurface for Transmitted Wavefront Modulation" published in the PHYSICAL REVIEW APPLIED journal in 2018 explores the development of a novel technology known as a continuously tunable acoustic metasurface. The research was conducted by Sheng-Dong Zhao, A-Li Chen, Yue-Sheng Wang, and Chuanzeng Zhang from various institutions in China and Germany. This innovative acoustic metasurface is designed to have the capability of continuously tuning its acoustic properties to control the transmission of acoustic waves. By modulating the transmitted wavefront, this metasurface opens up new possibilities for various applications in acoustics and engineering. The researchers focused on the development of a metasurface that can manipulate the transmitted wavefront with high precision and adjustability. The study involved the design, fabrication, and testing of the continuously tunable acoustic metasurface. The researchers conducted experiments to demonstrate the effectiveness of the metasurface in controlling the transmitted acoustic wavefront. The results showed that the metasurface was able to achieve precise and continuous modulation of the transmitted wavefront, showcasing its potential for use in various acoustic devices and systems. Overall, the research presented in this article represents a significant advancement in the field of acoustic metasurfaces and their application in controlling acoustic waves. The continuously tunable nature of this metasurface offers new opportunities for the development of advanced acoustic devices with improved performance and functionality. The findings of this study contribute to the growing body of knowledge in acoustic engineering and pave the way for future innovations in this field.

CONTINUOUSLY TUNABLE ACOUSTIC METASURFACE. . . PHYS. REV. APPLIED 10, 054066 (2018)

microstructures with a graded variation of geometry to

reshape the reﬂected or transmitted phase proﬁle. Among

various metasurface design strategies, the most represen-

tative material microstructure is the labyrinth type, which

has been proposed by Liang and Li [11], see Fig. 1(b).

The space-coiling design will force the acoustic waves to

propagate through the labyrinth passages, which are much

longer than their external dimension. As shown in the

example of Fig. 1(b), a large phase delay, ϕ = k

H =

eﬀ

L, is introduced within a small space, where k

is the

wave number in the background ﬂuid, H is the channel

length of the “sound path,” and n

eﬀ

is the eﬀective refrac-

tive index, see Fig. 1(c). Then units with designed gradient

channel lengths constitute a metasurface, and the chan-

nel length variation should be predeﬁned to match the

needed phase proﬁle. As a result, the transmitted phase

proﬁle is reshaped [Fig. 1(b)]. However, once manufac-

tured, the traditional space-coiled metasurfaces cannot be

tuned again to meet diﬀerent phase modulations. There-

fore, a continuously tunable channel length and a ﬂexible

phase regulation spurs designers to obtain a continuously

tunable metasurface. To this end, one should construct

reconﬁgurable phase delays to realize a broadband tunable

phase proﬁle by reconstructing the geometrical gradient.

The present design can fully achieve this purpose, and

its basic idea will be introduced and described in the

following.

Based on a screw-and-nut mechanism, we propose

a continuously tunable metasurface composed of spiral

channel units as shown in Fig. 1(d). When the screwed

depth (L



) is tuned, the spin-number as well as the trans-

mitted phase proﬁle changes to meet various metasurface

functions. Similar to the labyrinth passage, the spiral chan-

nel will delay the phase as ϕ = k

H = n

eﬀ

L where the

channel length H, which is tunable with the screwed depth



,isH = 2π R



/W + L − L



with R

the eﬀective radius

of the spiral channel and W the thread lead [Fig. 1(e)].

In this way, the present ﬂexible tunable units constitute

a metasurface which can arbitrarily reshape the transmit-

ted wave front through a change of the screwed depth.

The designed helical unit components can be ﬂexibly

assembled into a two-dimensional (2D) metasurface [see

Fig. 2(a)] or even a curved metasurface. Such a tunability

mechanism is a signiﬁcant step to promote metasurfaces

for practical applications.

The detail of the tunable metasurface design is illus-

trated schematically in Fig. 2. Figure 2(a) shows the 2D

metasurface with distributed helical cylinders screwed into

a plate. The tunability of the metasurface is based on a

screw-and-nut mechanism with a tunable screwed depth,

as shown in Fig. 2(b). The plate is perforated with circular

holes, and the inside wall of each hole is cut into a left-

handed screw with shallow grooves [see Fig. 2(d)]. The

helical cylinder is partially screwed into the plate, and a tail

with the length of L − L



may remain outside. Hereafter,

(a) (b) (c)

(d)

FIG. 2. The detail of the tunable metasurface design based

on the screw-and-nut mechanism. (a) The anomalous refraction

phenomenon on the tunable metasurface is governed by the gen-

eralized Snell’s law. The gradient phase is tuned by the screwed

depth of the helical cylinders. (b) The helical cylinder with two

spiraling blades connected through a central slender column. The

cylinder is screwed into a block and then a tunable unit com-

ponent is combined. (c) The geometric details of the helical

cylinder. (d) The drilled hole with the inside wall cut into shallow

grooves.

this external part is called the “helix’s tail.” After partially

screwing the helical cylinder [Fig. 2(c)] into the hole, a spi-

ral channel is formed between the inside wall of the hole

and the helical cylinder. The channel length and thus the

transmitted phase can be continuously tuned by adjusting

the screwed depth. Thus a new degree of freedom for con-

trolling the wavefronts can be attained by introducing an

arbitrary form of the phase shift along the metasurface. The

wavefront modulation is based on Snell’s law. For the sake

of simplicity, we assume a one-way phase gradient along

the x direction as shown in Fig. 2(a). For an incident wave

in the x-z plane, the refraction angle θ

is determined by

Eq. (1), see also the schematic diagram of Fig. 2(a).

One of the key steps in the design of the tunable meta-

surface is to obtain the relationship between the phase

changes and the screwed depth of the helical cylinders at

diﬀerent frequencies with consideration for a high trans-

mission. Here, we would like to mention that a nontrans-

mitting material would be a better choice for the substrate

material used in the present design. As we have stated

before, the phase reshaping of the present metasurface

relies on the precisely designed spiral air channels. The

sound only propagates through the channels, and the grad-

ual variation of the microstructural geometry generates the

phase gradient and thus controls the transmitted sound [see

Figs. 1(b) and 1(c)]. The units of the spiral air channels

are distributed dispersively, and some parts of the metasur-

face consist of only substrate material without air channels

[see Fig. 1(c)]. If transmitting material is used, no phase

gradient can be generated when sound passes through the

substrate part without air channels. Therefore, a transmit-

ting substrate is not a good choice for the present design.

In fact, a high-energy transmittance should be guaranteed

054066-3

剩余14页未读，继续阅读

CAE工作者

粉丝: 217
资源: 1820

"可调透射的声学超表面：连续调节传输波前的物理评价应用"

Widely and continuously tunable continuum generation from CW-Pumped cascaded fibers

Compact Design of Planar Continuously Tunable Crossover With Two-Section Coupled Lines

Repetition rate continuously tunable 10-GHz picosecond mode-locked fiber ring laser

Proposal of switchable multiwavelength laser with continuously tunable spacing in MgO: APPLN waveguide

Widely and continuously tunable optical parametric generator based on MgO-doped periodically poled LiNbO3 crystal

Continuously tunable true-time delay lines based on a one-dimensional grating waveguide for beam steering in phased array antennas

HTTP Continuously

High output energy tunable alexandrite laser

A novel 852-nm tunable fiber laser

A Compact Narrow-Band Tunable Optical Transversal Filter

最新资源