Light Switching with a Metal-Free Chiral-Sensitive Metasurface at Telecommunication Wavelengths
Light Switching with a Metal-Free Chiral-Sensitive Metasurface at Telecommunication Wavelengths
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DOI：
10.1021/acsphotonics.0c01377
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发表时间：
2020-10-21
期刊：
影响因子：
7
通讯作者：
Delaunay, Jean-Jacques
中科院分区：
文献类型：
--
作者：
Deng, Chih-Zong;Ho, Ya-Lun;Delaunay, Jean-Jacques
控制光的传播方向或光开关，可以在高密度和复杂的光子集成器件中实现单个光学元件的寻址。因此，光开关对光子/等离子体集成电路的发展至关重要。利用金属纳米结构的手性敏感超表面，将不同自旋的入射光耦合到沿不同方向传播的表面等离子激元上，实现了光开关。然而，基于表面等离子激元的器件由于其金属层的欧姆损耗而存在传输长度短和共振波长范围窄的问题。布洛赫表面波可以看作是表面等离子激元的无金属类比，具有低传播损耗和宽工作波长范围等优越特性。在这里，我们展示了一个无金属手性敏感的布洛赫-表面波开关电路，由精心排列的u形孔阵列、引导板和光栅耦合器组成。通过对布洛赫表面波的振幅和相位进行工程设计，实现自旋控制的单向耦合，实现对布洛赫表面波传播方向的控制。在1550 nm的通信波长上，有很高的定向选择性，理论为23 dB，实验为13.5 dB。利用无金属手性敏感超表面在芯片上实现电信波长的自旋控制光开关的能力将有利于低损耗片上光子集成器件的发展。
Controlling the direction of light propagation, or light switching, enables the addressing of individual optical elements in high-density and complex photonic integrated devices. Light switching is therefore crucial to the development of photonic/plasmonic integrated circuits. Chiral-sensitive metasurfaces using metallic nanostructures have been used to realize light switching by coupling incident light of different spins to surface plasmon polaritons propagating in different directions. However, surface plasmon polaritons-based devices suffer from short propagation lengths and narrow resonance wavelength ranges resulting from ohmic losses in their metal layers. Bloch surface waves can be seen as a metal-free analogy to surface plasmon polaritons with superior properties such as low propagation losses and wide operating wavelength ranges. Here, we demonstrate a metal-free chiral-sensitive Bloch-surface-wave switching circuit consisting of a carefully arranged array of U-shaped apertures, guiding slabs, and grating couplers. By engineering the amplitude and phase of the Bloch surface wave to achieve spin-controlled unidirectional coupling, control of the propagation direction of the Bloch surface waves is realized. Very high directional selectivity is reported at the telecommunications wavelength of 1550 nm, both theoretically at 23 dB and experimentally at 13.5 dB. The ability to realize spin-controlled light switching on a chip at telecommunications wavelengths using metal-free chiral-sensitive metasurfaces should benefit the development of low-loss on-chip photonic integrated devices.