Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Urgell 187, Barcelona 08036, Spain.
Opt Lett. 2013 Jun 1;38(11):1890-2. doi: 10.1364/OL.38.001890.
We predict the existence of evanescent modes with unlocked phases in two-dimensional (2D) dielectric periodic structures. Contrary to what is known for one-dimensional structures, where evanescent fields lock to the host modulation, we show that in 2D systems a new class of evanescent modes exists with an unlocked real part of the wave vector. Hence, beams constructed from such unlocked evanescent waves can exhibit spatial effects. A significant focalization of a beam propagating within the band gap of a flat photonic crystal slab is also shown. The predicted phenomenon is expected to be generic for spatially modulated materials.
我们预测二维（2D）介电周期性结构中存在相位解锁的消逝模式。与一维结构中众所周知的情况相反，在一维结构中，消逝场锁定到宿主调制，我们表明在 2D 系统中存在一类新的消逝模式，其波矢的实部未锁定。因此，由这种未锁定的消逝波构成的光束可以表现出空间效应。还展示了在平板光子晶体的带隙中传播的光束的显著聚焦。预计这种预测的现象对于空间调制材料具有普遍性。
