Electro‐Optic Effect of ZnO Microcavity and Active Dynamic Lasing Mode Modulation

Electro-optic effect, as a physical effect of electric field modulating refractive index, is widely applied to modulate lasing modes dynamically. However, the modulation is operated passively in general. It means that the lasing is generated in a resonance cavity and the modes are regulated externally in different materials and spaces. It will be highly favorable for optoelectronic integration and other applications when a gain medium with electro-optic effect is applied to design an optical microcavity, integrating optical pumping and electro-optic modulation. In this work, a hexagonal ZnO microrod is pumped optically to generate UV lasing with an electric field applied to modulate dynamically the resonance wavelength. When the electric field is parallel to the ZnO C-axis, the refractive index variation is correlated linearly with the electric field strength (Pockels effect). When the electric field is perpendicular to the ZnO C-axis, the refractive index variation shows a quadratic increase tendency with the increase of the electric field strength (Kerr electro-optic effect). The whispering-gallery lasing modes are dynamically modulated by applying an electric field successfully. In one word, lasing generation and modulation are integrated in the same microcavity based on both 1st and 2nd order electro-optic effect.