Ultrathin and low-loss phase-change materials (PCMs) are highly valued for their fast and effective phase transitions and applications in reconfigurable photonic chips, metasurfaces, optical modulators, sensors, photonic memories, and neuromorphic computing. However, conventional PCMs mostly suffer from high intrinsic losses in the near-infrared (NIR) region, limiting their potential for high quality factor (Q-factor) resonant metasurfaces. Here we present the design and fabrication of tunable bound states in the continuum (BIC) metasurfaces using the ultra-low-loss PCM Sb₂Se₃. Our BIC metasurfaces, only 25 nm thick, achieve high modulation depth and broad resonance tuning in the NIR with high Q-factors up to 130. Experimentally, we employ these BIC metasurfaces to modulate photoluminescence in rare earth-doped upconversion nanoparticles, reducing the excitation power for multiphoton photoluminescence and enabling emission polarization manipulation. This work offers a promising platform for developing active resonant metasurfaces, with broad applications including optical modulation, ultrafast switches, color filtering, and optical sensing.

中文翻译：

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基于超低损耗 Sb2Se3 相变材料的超薄 BIC 超表面


超薄和低损耗相变材料 （PCM） 因其快速有效的相变以及在可重构光子芯片、超表面、光调制器、传感器、光子存储器和神经形态计算中的应用而受到高度重视。然而，传统相变材料在近红外 （NIR） 区域大多存在高本征损耗，限制了它们获得高品质因数 （Q 因子） 谐振超表面的潜力。在这里，我们介绍了使用超低损耗 PCM Sb₂Se₃ 在连续介质 （BIC） 超表面中设计和制造可调谐束缚态。我们的 BIC 超表面厚度仅为 25 nm，可在 NIR 中实现高调制深度和宽谐振调谐，Q 因子高达 130。在实验中，我们利用这些 BIC 超表面来调制稀土掺杂上转换纳米颗粒中的光致发光，从而降低多光子光致发光的激发功率并实现发射偏振操纵。这项工作为开发有源谐振超构表面提供了一个有前途的平台，其应用范围广泛，包括光调制、超快开关、颜色过滤和光学传感。