Quantum Dot Lasers- Lighting at the nanoscale

Overview

Topic status: We're looking for students to study this topic.

Background There is increasing interest in nanoscale light sources because of their potential to deliver novel lighting solutions for a diverse array of applications in integrated photonics1, single photon sources and detectors2, quantum computing3, medical imaging and cancer treatment4. Quantum Dots (QDs) show great promise as a viable source because of their ability to resist photo-bleaching as well as their overall higher luminescence when compared to organic dyes.

QDs are semiconductor nanocrystals with dimensions less than or comparable to the exciton bohr radius of the bulk semiconductor which is typically a few nanometres. When reduced to these sizes, the light emitted and absorbed by the QD becomes size dependent. This leads to the attractive prospect of the designer selecting the output wavelength of the medium purely by choice of QD dimensions, leading to tunable bandgap materials, and enhancing other optical properties, such as reducing emission line widths when compared to the emission from their bulk semiconductor counterparts. Despite these advantages, QDs have so far failed to reach the high expectations of industry due to their lower quantum efficiency.

To overcome poor efficiency and other problems, hybrid QD systems interacting with surface plasmons have been receiving considerable attention. Surface plasmons are surface electromagnetic waves that are physically a collective oscillation of the free electrons in metal nanostructures such as thin films and nanoparticles. When metal nanostructures are placed sufficiently close to QDs, energy can be transferred from one nanomaterial to the other and the combination can be treated as a coupled system.

The goal of this project is to fabricate nanoscale light sources from quantum dot-nanoparticle hybrid systems that are suitable for use in integrated photonic devices and biomedical applications. To succeed, two cutting-edge nanotechnologies must be literally and figuratively merged. Light emitting QDs are now attracting huge interest due to their user defined light emission properties. Similarly, much research is currently devoted to metallic nanoparticle as they have proven to be extremely efficient couplers of visible light energy into various systems. By combining these two areas we will create efficient new quantum dot based light sources - with emission properties designed by the user, which will be energized through illumination with light absorbed by attached metallic nanoparticles.

The project will include a combination of electromagnetic theory, quantum mechanics and solid state physics. Colloidal processes will be used to make the nanostructures.

References:

  • Chang, D.E.; S'rensen, A.S.; Demler, E.A.; Lukin, M.D. Nature Physics 2007, 3, 807-812.
  • Konstantatos, G.; Sargent, E. H. Nature Nanotechnology 2010, 5, 391-400.
  • Gershoni, D. Nature Photonics 2010, 4, 271-272.
  • Biju, V.; Itoh, T.; Anas, A.; Sujith, A.; Ishikawa, M. Anal. Bioanal. Chem. 2008, 391, 2469
Study level
Honours
Supervisors
QUT
Organisational unit

Science and Engineering Faculty

Research area

Physics

Contact

Please contact the supervisor.