We report holographic polymer-dispersed liquid crystal (H-PDLC) gratings driven by surface acoustic waves (SAWs). Our experiments show that upon applying SAWs, the H-PDLC grating exhibited switchable properties: The diffraction of the H-PDLC grating decreased, whereas the transmission increased. This acoustically switchable behavior is due to the acoustic streaming-induced realignment of liquid crystals as well as absorption-resulted thermal diffusion. Such SAW-driven H-PDLC gratings are potentially useful in many photonic applications, such as optical switches, spatial light modulators, and switchable add/drop filters.
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http://dx.doi.org/10.1177/2211068212455632 | DOI Listing |
Adv Sci (Weinh)
November 2024
State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin, 150001, China.
Droplet manipulation technologies with surface acoustic waves attract significant attention for applications in fluid handling and bioanalysis. However, existing technologies face challenges in automation, precision, and functional integration, limiting broader applications. In this work, a highly integrated droplet-sensing acoustofluidic tweezer is developed, incorporating orthogonally arranged slanted finger interdigital transducers and a custom-designed control and detection circuit system.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
October 2024
This work presents the development of switchable surface acoustic wave (SAW) resonators fabricated on a LiNbO3 substrate, which uses the electrical Bragg bandgap concept to control the resonance frequency. The modification of the electrical condition of electrode arrays shifts their bandgap center frequency, which in turn changes the effective cavity length and resonance frequency of the resonator. This method uses the electrodes already present in SAW devices, thus reducing the complexity of potentially tunable SAW components.
View Article and Find Full Text PDFImaging the complex dynamics of micro-vibrations plays a fundamental role in the investigation of microelectromechanical systems (MEMS). However, it remains a challenge for achieving both a wide bandwidth and a low noise due to the high photodetector noise and electromagnetic interference at GHz frequencies. Here, we propose a pulsed laser interferometry system with an adaptable switch to image GHz vibrations based on stroboscopic mixing, while measuring lower-frequency vibrations based on the homodyne scheme.
View Article and Find Full Text PDFJ Biophotonics
May 2024
Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, The University of Texas at Arlington, Arlington, Texas, USA.
Ultrasound switchable fluorescence (USF) imaging, a hybrid imaging technology that combines the advantages of both fluorescence sensitivity and acoustic resolution in centimeter-deep tissue, has great potential for biomedical different applications. A camera-based USF imaging system reveals its capability of capturing both spatial and temporal dynamics of the USF signal in tissue. In this study, various algorithms were explored to enhance the spatial resolution and signal-to-noise ratio (SNR) of USF images, utilizing temporal and spatial information from a camera-based time-domain USF imaging system.
View Article and Find Full Text PDFNat Commun
February 2024
Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
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.
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