The evolution of the solitons in periodic photonic moiré lattices controlled by rotation angle with saturable self-focusing nonlinearity media

Abstract

Abstract We explored the evolution and stability of solitons formed by a Gaussian beam excited on-site in periodic photonic moiré lattices controlled by an angle with saturable self-focusing nonlinearity medium of lower applied bias, which makes use of the square lattices as a reference. When we introduce the rotation angle θ ( θ ∈ ( 0 , π / 2 ) ), which satisfies the Pythagorean theorem and is commensurable, it will create a new lattice structure by rotating and superimposing two square lattices of the same period, which we called periodic photonic moiré lattices. Its energy band structure is special, which includes the flat band, and even opens the higher band-gap compared with square lattices. On the other hand, when we reduce the applied bias of the crystal, periodic photonic moiré lattices can still suppress the diffraction behaviour of Gaussian beam effectively and realize light localization by contrast with square lattices. Moreover, we proved the stability of the solitons formed by the Gaussian beams excited on-site in periodic photonic moiré lattices and revealed that the solitons could keep stable, but their stability regimes depend on the rotation angle shrinks and belong to the different bandgap. The discovery of the photonic moiré lattice provides a fresh approach for suppressing the diffraction behaviour of light and reduces the requirement for nonlinearity, which is beneficial for the diversity of our crystal material selection, and also provides a new way to manufacture high-efficiency optoelectronic devices.