Localized dynamics arising from multiple flat bands in a decorated photonic Lieb lattice

Abstract

Photonic lattices have emerged as an ideal testbed for localizing light in space. Among others, the most promising approach is based on flat band systems and their related nondiffracting compact localized states. So far, only compact localized states arising from a single flat band have been found. Such states typically appear static, thus not allowing adaptive or evolutionary features of light localization. Here, we report on the first experimental realization of an oscillating compact localized state arising from multiple flat bands. We observe an oscillatory intensity beating during propagation in a two-dimensional photonic decorated Lieb lattice. The photonic system is realized by direct femtosecond laser writing and hosts most importantly multiple flat bands at different eigenenergies in its band structure. Our results open new avenues for evolution dynamics in the up to now static phenomenon of light localization in periodic waveguide structures and extend the current understanding of light localization in flat band systems.

Tilted Dirac cones and asymmetric conical diffraction in photonic Lieb-kagome lattices

“…In order to verify our results experimentally, we fabricated photonic lattices in fused silica (SiO 2 ) using the direct laser writing technique [24,40]. Table II shows the main differences in parameters compared to the simulations presented so far.…”

“…The Lieb lattice and the kagome lattice are two types of artificial lattices, which have long been studied theoretically, because they feature both Dirac cones and completely dispersionless flat bands. They can be easily realized as photonic lattices, and as such have been studied in the context of localized (flat band) states [22][23][24], conical diffraction [20,25,26], and topological insulators [27]. The Lieb and the kagome lattice are related by a shearing transformation and can be continuously transformed into each other.…”

Pseudospin-2 in photonic chiral borophene

“…The simulations are based on the paraxial wave equation and are carried out via a standard pseudospectral split-step propagation method [29]. The numerical parameters are chosen to be within the experimental reach and match those in previously reported experiments in laser-written photonic lattices with a refractive index contrast of the waveguides Δn 1.3 × 10 −3 , wavelength of λ 532 nm, and nearest neighbor waveguide separation of Λ 18 μm [30,31].…”

“…(A1) can be obtained via the split-step Fourier transform method [29]. In our numerical simulations, we adapt the parameters to match previously reported experiments in laser-written photonic lattices [30,31]. We choose n 0 1.4 and k 0 2π∕λ 0 with λ 0 532 nm.…”