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

✍ Scribed by Karoline A. Piegdon; Matthias Offer; Axel Lorke; Martin Urbanski; Andreas Hoischen; Heinz-S. Kitzerow; Stefan Declair; Jens Förstner; Torsten Meier; Dirk Reuter; Andreas D. Wieck; Cedrik Meier

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 394 KB
• Volume: 42
• Category: Article
• ISSN: 1386-9477
• DOI: 10.1016/j.physe.2009.12.051

✦ Synopsis

GaAs-based semiconductor microdisks with high quality whispering gallery modes (Q 4 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 À cyano À 4 0 Àpentylbiphenyl (5CB), a liquid crystal (LC) with a nematic phase below the clearing temperature of T C % 34 3 C. We have studied the device performance in the temperature range of T ¼ 20250 3 C, 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.