More Like this

1. Electrically driven reprogrammable phase-change metasurface reaching 80% efficiency

   https://doi.org/10.1038/s41467-022-29374-6  

   Abdollahramezani, Sajjad; Hemmatyar, Omid; Taghinejad, Mohammad; Taghinejad, Hossein; Krasnok, Alex; Eftekhar, Ali A.; Teichrib, Christian; Deshmukh, Sanchit; El-Sayed, Mostafa A.; Pop, Eric; et al (March 2022, Nature Communications)

   Abstract Phase-change materials (PCMs) offer a compelling platform for active metaoptics, owing to their large index contrast and fast yet stable phase transition attributes. Despite recent advances in phase-change metasurfaces, a fully integrable solution that combines pronounced tuning measures, i.e., efficiency, dynamic range, speed, and power consumption, is still elusive. Here, we demonstrate an in situ electrically driven tunable metasurface by harnessing the full potential of a PCM alloy, Ge₂Sb₂Te₅(GST), to realize non-volatile, reversible, multilevel, fast, and remarkable optical modulation in the near-infrared spectral range. Such a reprogrammable platform presents a record eleven-fold change in the reflectance (absolute reflectance contrast reaching 80%), unprecedented quasi-continuous spectral tuning over 250 nm, and switching speed that can potentially reach a few kHz. Our scalable heterostructure architecture capitalizes on the integration of a robust resistive microheater decoupled from an optically smart metasurface enabling good modal overlap with an ultrathin layer of the largest index contrast PCM to sustain high scattering efficiency even after several reversible phase transitions. We further experimentally demonstrate an electrically reconfigurable phase-change gradient metasurface capable of steering an incident light beam into different diffraction orders. This work represents a critical advance towards the development of fully integrable dynamic metasurfaces and their potential for beamforming applications. 

   more » « less
2. Generation of Light Transverse Spin with a Vectorial Field Controlling Metasurface

   https://doi.org/10.1364/CLEO_QELS.2022.FM4H.2  

   Terekhov, Pavel; Rahman, Md Tarek; Ding, Yimin; Zhang, Xingwang; Ni, Xingjie (January 2022, 2022 Conference on Lasers and Electro-Optics (CLEO))

   We demonstrate the direct generation of focused transverse spin of light with a metasurface fully controlling the vectorial properties of the transmitted light field through sub-wavelength pixelized manipulation of phase, polarization, and amplitude independently. 

   more » « less
3. Electroelastic metasurface with resonant piezoelectric shunts for tunable wavefront control

   https://doi.org/10.1088/1361-6463/acbd5f  

   Lin, Z.; Tol, S. (March 2023, Journal of Physics D: Applied Physics)

   Abstract In this paper, we design a tunable phase-modulated metasurface composed of periodically distributed piezoelectric patches with resonant-type shunt circuits. The electroelastic metasurface can control the wavefront of the lowest antisymmetric mode Lamb wave (A₀mode) in a small footprint due to its subwavelength features. The fully coupled electromechanical model is established to study the transmission characteristics of the metasurface unit and validated through numerical and experimental studies. Based on the analysis of the metasurface unit, we first explore the performance of electroelastic metasurface with single-resonant shunts and then extend its capability with multi-resonant shunts. By only tuning the electric loads in the shunt circuits, we utilize the proposed metasurface to accomplish wave deflection and wave focusing ofA₀mode Lamb waves at different angles and focal points, respectively. Numerical simulations show that the metasurface with single-resonant shunts can deflect the wavefront of 5 kHz and 6 kHz flexural waves by desired angles with less than $2\mathrm{\%}$deviation. In addition, it can be tuned to achieve nearly three times displacement amplification at the designed focal point for a wide range of angles from $-{75}^{\circ }$to 75^∘. Furthermore, with multi-resonant shunts, the piezoelectric-based metasurface can accomplish anomalous wave control over flexural waves at multiple frequencies (i.e. simultaneously at 5 kHz and 10 kHz), developing new potentials toward a broad range of engineering applications such as demultiplexing various frequency components or guiding and focusing them at different positions. 

   more » « less
4. Single atom trapping in a metasurface lens optical tweezer

   https://doi.org/10.48550/arXiv.2110.11559  

   Hsu, T-W; Zhu, W.; Thiele, T.; Brown, M.O.; Papp, S.B.; Agrawal, A.; Regal, C.A. (July 2022, ArXivorg)

   Optical metasurfaces of sub-wavelength pillars have provided new capabilities for the versatile definition of the amplitude, phase, and polarization of light. In this work we demonstrate that an efficient dielectric metasurface lens can be used to trap and image single neutral atoms. We characterize the high numerical aperture optical tweezers using the trapped atoms and compare to numerical computations of the metasurface lens performance. We predict future metasurfaces for atom trapping can leverage multiple ongoing developments in metasurface design and enable multifunctional control in complex experiments with neutral-atoms arrays. 

   more » « less
5. Electrically driven thermal infrared metasurface with narrowband emission

   https://doi.org/10.1063/5.0116880  

   Liu, Xiu; Jing, Lin; Luo, Xiao; Yu, Bowen; Du, Shen; Wang, Zexiao; Kim, Hyeonggyun; Zhong, Yibai; Shen, Sheng (September 2022, Applied Physics Letters)

   Metasurfaces consisting of an array of planar sub-wavelength structures have shown great potentials in controlling thermal infrared radiation, including intensity, coherence, and polarization. These capabilities together with the two-dimensional nature make thermal metasurfaces an ultracompact multifunctional platform for infrared light manipulation. Integrating the functionalities, such as amplitude, phase (spectrum and directionality), and polarization, on a single metasurface offers fascinating device responses. However, it remains a significant challenge to concurrently optimize the optical, electrical, and thermal responses of a thermal metasurface in a small footprint. In this work, we develop a center-contacted electrode line design for a thermal infrared metasurface based on a gold nanorod array, which allows local Joule heating to electrically excite the emission without undermining the localized surface plasmonic resonance. The narrowband emission of thermal metasurfaces and their robustness against temperature nonuniformity demonstrated in this work have important implications for the applications in infrared imaging, sensing, and energy harvesting. 

   more » « less