Single-defect mode lasing in a non-Hermitian 1D trivial SSH lattice

We demonstrate robust single-mode lasing in a non-Hermitian 1D trivial Su-Schrieffer-Heeger defective lattice. This structure exhibits a significantly lower threshold power compared to the non-defective lattice, with single-mode lasing sustained across a wide range of pump powers. Notably, our proposed device requires pumping of only the defect ring, leading to minimal required pump power. Moreover, lasing is not confined to the edges but can occur at any point within the lattice.