仅用两个频率合成超振荡
Synthesizing superoscillations with just two frequencies
AI总结：
研究仅用两个频率合成超振荡的方法，通过重新分析及新实验，证明可使局部频率相对于最高频率分量提高两倍，基于相消干涉给出解析解释并确定最佳频率间隔，降低了超振荡技术的实验障碍。
AI中文摘要：
超振荡是一种带限信号，其局部振荡速度比最高傅里叶分量更快，近来已应用于超光谱学和超传感领域。以往实验依靠组合四个准正弦谐波来产生时间超振荡。本文表明仅两个谐波就足以产生质量相当的超振荡。通过重新分析两个谐波（0.5和0.6太赫兹）的先前实验数据并开展0.9和1太赫兹谐波的新实验，证明局部频率相对于最高频率分量提高了两倍。基于近乎完全相消干涉为双色超振荡提供了简单解析解释，确定了约10%的最佳频率间隔，平衡了超振荡频率增强与信号幅度。这种简化大幅降低了基于超振荡技术的实验障碍。
英文摘要：
Superoscillations, band-limited signals that locally oscillate faster than their highest Fourier component, have recently enabled superspectroscopy and super-sensing. Previous experiments [Phys. Rev. Lett. 131, 153803 (2023), https://doi.org/10.1103/PhysRevLett.131.153803 and APL Photonics 10, 086107 (2025), https://doi.org/10.1063/5.0271556] relied on combining four quasi-sinusoidal harmonics to generate temporal superoscillations. Here, we show that just two harmonics are sufficient to produce superoscillations of comparable quality, as quantified by the local frequency. By reanalyzing prior experimental data with two harmonics (0.5 and 0.6 THz) and performing new experiments with 0.9 and 1 THz harmonics, we demonstrate a twofold enhancement in local frequency relative to the highest frequency component -- matching the enhancement previously achieved with four harmonics. We provide a simple analytical explanation for the bichromatic superoscillations based on near-complete destructive interference, and identify an optimal frequency separation of approximately 10% that balances the superoscillatory frequency enhancement against signal amplitude. This simplification substantially lowers the experimental barrier to implementing superoscillation-based technology.
