Ultrafast control of light−matter interactions is fundamental in view of new technological frontiers of information processing. However, conventional optical elements are either static or feature switching speeds that are extremely low with respect to the time scales at which it is possible to control light. Here, we exploit the artificial epsilon-near-zero (ENZ) modes of a metal-insulator-metal nanocavity to tailor the linear photon absorption of our system and realize a nondegenerate all-optical ultrafast modulation of the reflectance at a specific wavelength. Optical pumping of the system at its high energy ENZ mode leads to a strong redshift of the low energy mode because of the transient increase of the local dielectric function, which leads to a sub-3-ps control of the reflectance at a specific wavelength with a relative modulation depth approaching 120%.

鉴于信息处理的新技术前沿，对光与物质相互作用的超快控制是基本的。然而，相对于可以控制光的时间尺度，常规光学元件要么是静态的，要么是特征切换速度极低的。在这里，我们利用金属-绝缘体-金属纳米腔的人工ε-近零（ENZ）模式来调整系统的线性光子吸收，并实现特定波长下反射率的简并全光学超快调制。由于局部介电函数的瞬时增加，以高能量ENZ模式进行系统的光泵浦会导致低能量模式发生强烈的红移，