Lasing-Mode Switch of a Hexagonal ZnO Pyramid Driven by Pressure within a Diamond Anvil Cell.

Nanolasers are expected to be integrated on chips as miniaturized coherent light sources, and their application is strongly dependent on their lasing behavior. In this work, the lasing behavior of a single hexagonal ZnO pyramid (HZOP) is tailored by tuning the electronic bandgap with pressure. The lasing of the HZOP nanolaser is dominated by a helical whispering-gallery-like mode, and the lasing threshold varies little with increasing pressure. All lasing peaks of HZOP are limited in a spectral prescreen window on the right shoulder of the fluorescence emission and gradually blue-shift accompanied by several abrupt hops with increasing pressure. This feature of a spectral prescreen window originates from the strong coupling between excitons, and the coupling is described by a dispersive complex refractive index. These results provide a new perspective to tune and switch the lasing mode of a nanolaser with precision by the pressure-induced bandgap broadening of a semiconductor.