Self-assembled quantum dots in a liquid-crystal-tunable microdisk resonator

GaAs-based semiconductor microdisks with high quality whispering gallery modes (Q>4000) have been fabricated. A layer of self-organized InAs quantum dots (QDs) served as a light source to feed the optical modes at room temperature. In order to achieve frequency tuning of the optical modes, the microdisk devices have been immersed in 4-cyano-4′-pentylbiphenyl (5CB), a liquid crystal (LC) with a nematic phase below the clearing temperature of View the MathML source. We have studied the device performance in the temperature range of View the MathML source, in order to investigate the influence of the nematic–isotropic phase transition on the optical modes. Moreover, we have applied an AC electric field to the device, which leads in the nematic phase to a reorientation of the anisotropic dielectric tensor of the liquid crystal. This electrical anisotropy can be used to achieve electrical tunability of the optical modes. Using the finite-difference time domain (FDTD) technique with an anisotropic material model, we are able to describe the influence of the liquid crystal qualitatively.