Title: Defying the Laws of Optics -- Using Light to Study Quantum Dots

    Speaker: Prof. James L. Merz，Department of Electrical Engineering, University of Notre Dame

    Time: Apr.21, 2015 10:00AM

    Venue:  No. 101 Meeting Room, IOS, CAS

    Abstract: This talk will describe the use of Near-field Scanning Optical Microscopy (NSOM) to investigate fundamental properties of quantum structures in compound semiconductors. Spatial resolution of ~40 nm has been achieved, at liquid He temperatures and magnetic fields up to 10T, using both CW and psec time-resolved spectroscopy. Three examples of these studies will be briefly described: (1) dilute nitrides; i.e., GaAs doped with very low concentrations of N; (2) whispering gallery modes in micro disks containing quantum dots, and (3) attempts to create and measure Wigner localization of electrons in large (~100 nm) dots.

    Prof. James L. Merz received the B. Sc degree from Notre Dame University in 1959 and Ph.D. degree from Harvard University in 1967. He is American Physics Society fellow. Prof. Merz’s primary research field is the optical spectroscopy of semiconductor nanostructures. Other fields of interest include optoelectronic devices and photonic integrated circuits, defects in solids, ion implantation and rapid annealing. Several projects are currently underway in his laboratory: (1) His group has measured the clustering of nitrogen in short-period superlattices of InGaAsN and GaAsN using near-field scanning optical microscopy (NSOM) at magnetic fields up to 10 Tesla. Both weak and strong localization effects have been observed and are being investigated. (2) His group is developing a novel technique referred to as “nanoindentation”, where significant high-energy shifts of quantum dot (QD) emission have been induced by pressure applied by the near-field optical fiber probe in physical contact with the surface. This effect may be usable to allow sensitive modulated-pressure experiments, and to tune quantum dot emission to resonance with other dots for communications and computer applications. (3) Surface plasmon interactions between the optical field and metal cladding of an optical fiber are being investigated. (4) Photonic bandgap structures which contain QDs are being fabricated for possible quantum computing applications.