We address exotic optical response of a planar metasurface comprising a monolayer of regularly spaced quantum three-level emitters with a doublet in the ground state (the so-called Λ-emitters). All emitters are coupled by the retarded dipole field which depends on the current state of all emitters. This coupling introduces a feedback into the system. Complex interplay of the latter with the intrinsic nonlinearity of a three-level system results in several remarkable effects in the monolayer’s optical response, such as multistability, self-oscillations, and chaos. The peculiarity of the considered system is that some of the predicted nonlinear effects manifest themselves at very low excitation field intensities (on the order of 1 W/cm²), which is advantageous for possible applications: the monolayer can operate as a perfect reflector, a bistable mirror, and a THz or noise generator. It is argued therefore that the proposed system is a promising candidate for a building block for various photonic nano-devices.

我们解决了平面超表面的奇异光学响应，该超表面包括单层规则间隔的量子三级发射器，基态双峰（所谓的 Λ 发射器）。所有发射器都通过延迟偶极场耦合，这取决于所有发射器的当前状态。这种耦合将反馈引入系统。后者与三能级系统的内在非线性的复杂相互作用导致了单层光响应的几个显着影响，例如多稳态、自振荡和混沌。所考虑系统的特点是一些预测的非线性效应在非常低的激发场强度下表现出来（大约 1 W/cm ²)，这对于可能的应用是有利的：单层可以作为完美的反射器、双稳态反射镜和太赫兹或噪声发生器。因此，有人认为，所提出的系统是各种光子纳米器件的构建块的有希望的候选者。