Maximizing Focus Quality Through Random Media with Discrete-Phase-Sampling Lenses

Wang, Qiyuan; Fink, Mathias; Ma, Guancong

doi:10.1103/physrevapplied.19.034084

Cited by 7 publications

(5 citation statements)

References 47 publications

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“…Imaging techniques such as phase conjugation, inversed filtering, together with prior knowledge of the acoustic environment, are also viable routes for improving the outcomes 32 . Second, better results are expected if the phase modulation is of a finer phase sampling rate, e.g., a four-phase modualtion 33 . However, this is at the cost of longer optimization time.…”

Section: Discussionmentioning

confidence: 99%

Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces

Zhang,

Wang,

Fink

et al. 2024

Nat Commun

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Sound in indoor spaces forms a complex wavefield due to multiple scattering encountered by the sound. Indoor acoustic communication involving multiple sources and receivers thus inevitably suffers from cross-talks. Here, we demonstrate the isolation of acoustic communication channels in a room by wavefield shaping using acoustic reconfigurable metasurfaces (ARMs) controlled by optimization protocols based on communication theories. The ARMs have 200 electrically switchable units, each selectively offering 0 or π phase shifts in the reflected waves. The sound field is reshaped for maximal Shannon capacity and minimal cross-talk simultaneously. We demonstrate diverse acoustic functionalities over a spectrum much larger than the coherence bandwidth of the room, including multi-channel, multi-spectral channel isolations, and frequency-multiplexed acoustic communication. Our work shows that wavefield shaping in complex media can offer new strategies for future acoustic engineering.

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Section: Discussionmentioning

confidence: 99%

Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces

Zhang,

Wang,

Fink

et al. 2024

Nat Commun

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“…As the grey line shown in figure 9(c), the intensity distribution of the transverse electric field at the focus point significantly deviates from the ideal Gaussian distribution, leading to the poor focusing quality of 1.83 × 10 5 , just 29% of the ideal values. Notably, this focus field distribution is calculated numerically based on the Huygens-Fresnel principle and employs the asymptotic form to simplify computations [58]. Focusing efficiency (FE) is defined as the ratio of optical intensity at the focal spot to the input intensity [19].…”

Section: Enhanced Beam Focusing Via Inverse Designmentioning

confidence: 99%

“…However, direct optimization of FE can mislocate the peak energy positions, leading to a distorted focal point. Therefore, our approach advances beyond mere FE optimization by improving the contrast between the focal point and its surroundings, thereby elevating focusing quality (FQ), defined as [58]: Where, ( ) I x is the field distribution in the focal plane, D is the radius of the device. Therefore, the inverse design method aims to maximize these two parameters, defined as FOM FE FQ.…”

Section: Enhanced Beam Focusing Via Inverse Designmentioning

confidence: 99%

Dual-parameter controlled reconfigurable metasurface for enhanced terahertz beamforming via inverse design method

Wu,

Fan,

Qin

et al. 2024

Phys. Scr.

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Recently, reconfigurable metasurfaces have emerged as a promising solution for wavefront manipulation in the terahertz (THz) region, providing enhanced beamforming capabilities. However, traditional single-parameter control methods fail to achieve independent phase and amplitude modulation, constraining their modulation capabilities. Meanwhile, forward design methods based on phase matching ignore the structural responses of the non-ideal unit, leading to degraded beamforming performance. Here, we introduce an electrically reconfigurable metasurface composed of bilayer graphene strips based on dual-parameter control. Full-wave simulations demonstrate independent amplitude and phase modulation, achieving the full 360° phase coverage and an adjustable amplitude range from 0 to 0.8 at 2.6 THz. To optimize beamforming performance, particularly for the responses of the non-ideal unit away from the designed frequency, we employed an inverse design method based on a hybrid evolutionary algorithm. This novel approach significantly enhances beam steering, achieving a maximum 60% increase in beam directivity and maintaining over 90% of ideal directivity across a broad frequency range from 1.6 THz to 5 THz. Especially, it achieves a maximum deflection angle of 75°. Meanwhile, the adaptability of the inverse design method is further demonstrated to various optimized objectives. For beam focusing, even with limited phase control (below 210°), this method significantly enhances the focusing quality (up to 150% enhancement) and increases the focusing efficiency from 25% to 40%. Additionally, it effectively mitigates the impact of quantized phase errors on beamforming. This research not only demonstrates potential applications in high-speed THz wireless communication and compact imaging systems, but also paves the way for innovative designs in reconfigurable metasurfaces.

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“…The selection of various protocols can significantly impact the overall quality of the constructed field. [30] Therefore, both an efficient algorithm and a well-defined evaluation method are highly required to optimize the phase distribution on the emitting surface, ultimately maximizing the quality of OAM beams, which thereby leads to the enhanced performance in constructing the twisted ultrasonic motor and opens up new avenues for technological advancements in OAM-based applications.…”

Section: Doi: 101002/aisy202300255mentioning

confidence: 99%

Inverse‐Design Methodology for Generating Twisted Ultrasonic Motor in Free Space

Zhang,

He,

Jiang

et al. 2023

Advanced Intelligent Systems

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A new level of freedom is made possible by orbital angular momentum (OAM), which can be used to create twisted ultrasonic motors for particle manipulation and control. For steady and free‐flowing particle management, it is essential to produce acoustic OAM beams of high order and high quality. However, this task is difficult due to the phased array's fundamental restriction of insufficient resolution or aperture. Herein, a generic approach is presented to inverse design that may be used to improve the OAM beam quality and produce twisted ultrasonic motors in free space. In comparison to the previous direct‐design method, up to a 14% improvement in amplitude uniformity and a 12 dB improvement in signal‐to‐noise ratio (SNR) of OAM modes are achieved. These notable benefits enable the ultrasonic motor to operate with a straightforward and compact system while enabling steady particle rotation in free space with an undersampled phased array, which is not possible with the conventional technique. This study paves the way for effective particle control, high‐fidelity communication, and other OAM‐based technologies by providing an inverse‐design framework for optimizing OAM.

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Maximizing Focus Quality Through Random Media with Discrete-Phase-Sampling Lenses

Cited by 7 publications

References 47 publications

Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces

Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces

Dual-parameter controlled reconfigurable metasurface for enhanced terahertz beamforming via inverse design method

Inverse‐Design Methodology for Generating Twisted Ultrasonic Motor in Free Space

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