Nonreciprocal metasurface with space-time phase modulation

• 来源期刊: 光：科学与应用（英文版）
• 年，卷（期）: 2019,（6）
• 页码范围: 1181-1189
• 页数: 9页
• 语种: 英文

摘要

Creating materials with time-variant properties is critical for breaking reciprocity that imposes fundamental limitations on wave propagation.However,it is challenging to realize efficient and ultrafast temporal modulation in a photonic system.Here,leveraging both spatial and temporal phase manipulation offered by an ultrathin nonlinear metasurface,we experimentally demonstrated nonreciprocal light reflection at wavelengths around 860 nm.The metasurface,with travelling-wave modulation upon nonlinear Kerr building blocks,creates spatial phase gradient and multi-terahertz temporal phase wobbling,which leads to unidirectional photonic transitions in both the momentum and energy spaces.We observed completely asymmetric reflections in forward and backward light propagations over a large bandwidth around 5.77 THz within a sub-wavelength interaction length of 150 nm.Our approach highlights a potential means for creating miniaturized and integratable nonreciprocal optical components.