Sub-diffraction Integration and Non-invasive Manipulation by Nanophotonics

Lih Lin
UW Electrical Engineering

Three-dimensionally confined nanoparticles that harvest strong near-field interaction with light, such as colloidal quantum dots (QD) and Au nanoparticles, have opened new directions in nanophotonic devices and integration, as well as applications in biomedicine such as cancer cell ablation, drug delivery, and bio-manipulation. In this presentation, we will describe our research progress on (1) sub-diffraction QD cascade waveguides and photodetector, and (2) opto-plasmonic tweezers. The QD cascade waveguide consists of a linear array of QDs fabricated via molecular self-assembly. It utilizes gain and stimulated emission through each QD to achieve low transmission loss, and near-field optical coupling to achieve low crosstalk therefore high integration density. The nano-scale QD photodetector consists of a few QDs assembled in between a pair of narrowly-spaced electrodes. It provides the interface between a QD nanophotonic integrated circuits and the external electronic world. The opto-plasmonic tweezers (OPT) is a new approach for manipulation and rotation of biological cells, molecules, and micro/nano-particles. The platform builds on an array of Au nanoparticles, with localized surface plasmon resonance induced by polarized laser light. The highly non-uniform radiation field generated by the surface plasmon creates large dielectrophoretic force on dielectric objects nearby. By changing the polarization orientation of the incident light, the radiation pattern can be changed, thus achieving fine orientation control of the objects.