Fig 4
From: ZnO-Based Microcavities Sculpted by Focus Ion Beam Milling
Power-dependent lasing spectra of ZnO MCs with a circular, b square, c pentagonal, and d hexagonal shapes. Red lines represent distinct emission spectra under different pumping power densities. Insets in the figures show the integrated PL intensity as a function of excitation energy density labeled by black solid dots. The threshold power densities are 1.94, 2.63, 0.26, and 1.33 MW/cm2 for circular, square, pentagonal, and hexagonal shapes, respectively