Coupled guided modes lasing in hollow hexagonal cavities with an internal hexagon

22-bounce coupled guided modes were proposed in hollow hexagonal cavities attached internally with a hexagon. The proposed modes were demonstrated with lasing experiments using semiconductor-based cavities. The measured mode spacing agreed well to the one calculated from the coupled guided modes and decreased with the size of the internal hexagon. The experimental results showed that the proposed modes were widely tunable with a common outer size.