Observation of intensity flattened phase shifting enabled by unidirectional guided resonance
Observation of intensity flattened phase shifting enabled by unidirectional guided resonance
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DOI：
10.1515/nanoph-2021-0393
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发表时间：
2021-11
期刊：
影响因子：
7.5
通讯作者：
Zixuan Zhang;Xuefan Yin;Zihao Chen;Feifan Wang;Weiwei Hu;Chao Peng
中科院分区：
文献类型：
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作者：
Zixuan Zhang;Xuefan Yin;Zihao Chen;Feifan Wang;Weiwei Hu;Chao Peng
摘要纯相位光调制是光电子领域的一项重要应用。虽然利用光共振可以显著提高调制效率，但共振失谐总是伴随着不太理想的剧烈强度变化。在这里，我们提出了一种方法来实现强度平坦相移利用单向引导共振（UGR）-一类新型的拓扑使能引导共振，只向一侧辐射。因此，入射光激发共振并产生相移，但它只能传输到一个出射端口，没有其他选择，这会影响透射率。理论和模拟吻合良好，并证实了我们的研究结果，特别是当非辐射损失已被考虑在内。通过直接测量UGR样品的强度和相位响应，在非辐射Q约为2500时观察到0.43的倾角深度。我们进一步预测，在最先进的制造精度下，可以在8000左右的合理非辐射Q下实现0.13的凹陷深度，这对于从光投影、平面超透镜光学器件、光学相控阵到光检测和测距的应用是足够和有用的。
Abstract Phase-only light modulation is an important functionality for many optoelectronic applications. Although modulation efficiency can be significantly improved by using optical resonances, resonance detuning is always accompanied with dramatic intensity variation that is less ideal. Here, we propose a method to achieve intensity-flattened phase shifting by utilizing the unidirectional guided resonance (UGR) – a novel class of topologically enabled guided resonance that only radiates toward a single side. Consequently, the incident excites resonances and generates phase shifting, but it transmits to only one out-going port without other choice, which flattens the transmittance. Theory and simulation agree well and confirm our findings, in particular when nonradiative loss has been taken into account. By directly measuring the intensity and phase responses of UGR samples, a dip depth of 0.43 is observed with nonradiative Q around 2500. We further predict a dip depth of 0.13 can be achieved with a reasonable nonradiative Q around 8000 in state-of-art fabrication precision, which is sufficient and useful for the applications ranging from light projection, flat metalens optics, optical phased array, to light detection and ranging.