Mukherjee Sebabrata, Thomson Robert R
Opt Lett. 2017 Jun 15;42(12):2243-2246. doi: 10.1364/OL.42.002243.
We demonstrate that a flat-band state in a quasi-one-dimensional rhombic lattice is robust in the presence of external drivings along the lattice axis. The lattice was formed by periodic arrays of evanescently coupled optical waveguides, and the external drivings were realized by modulating the paths of the waveguides. We excited a superposition of flat-band eigenmodes at the input and observed that this state does not diffract in the presence of static, as well as high-frequency sinusoidal drivings. This robust localization is due to destructive interference of the analogous wavefunction and is associated with the symmetry in the lattice geometry. We then excited the dispersive bands and observed Bloch oscillations and coherent destruction of tunneling.
我们证明，在沿晶格轴存在外部驱动的情况下，准一维菱形晶格中的平带态是稳健的。该晶格由渐逝耦合光波导的周期性阵列形成，外部驱动通过调制波导路径来实现。我们在输入端激发了平带本征模的叠加，并观察到在静态以及高频正弦驱动存在的情况下，该状态不会发生衍射。这种稳健的局域化是由于类似波函数的相消干涉所致，并且与晶格几何结构中的对称性相关。然后我们激发了色散带，并观察到布洛赫振荡和隧穿的相干破坏。
