Events

From photon correlation Fourier spectroscopy to surface plasmon lasers: fundamental studies and applications of colloidal quantum dots

Dr. Jian Cui, ETH Zurich

Goergen Hall, Room 101

Abstract

Colloidal quantum dots are bright, robust, and tunable nanocrystalline semiconductor emitters used in optical applications including biological imaging, lighting, displays, and lasers. In this seminar, I present two sets of studies on these nanomaterials. The first is a deconstruction of the room temperature spectral linewidth of quantum dots using a recently developed spectroscopic technique. Photon-correlation Fourier spectroscopy in solution (S-PCFS) offers a unique approach to investigating single-emitter spectra with large sample statistics, without user selection bias, with high signal-to-noise ratios, and at fast timescales. With S-PCFS, we gain insight into the relative contributions of homogeneous and inhomogeneous broadening within a sample batch and the physical processes responsible for linewidth broadening in quantum dots at room temperature.

The second study is on the development of a highly customizable class of surface plasmon lasers, or “spasers”. Surface plasmon polaritons (or plasmons) are propagating electromagnetic waves bound to the surface of electron-rich materials such as metals and are potentially useful for applications such as integrated optical circuitry and sensing. However, their susceptibility to energetic losses has hindered their use in practical applications. Colloidal quantum dots, because of their photophysical properties and solution-processability, are an intriguing option as a gain medium for loss-compensation in plasmonic structures. By combining quantum dots with high-quality plasmonic cavities, we create a versatile class of spasers that allow controlled generation, extraction, and manipulation of monochromatic surface plasmons for on-chip use.

Bio

Jian Cui was born in Yanji, China in 1986 and moved to the US at the age of 5. He received his B.S. in Chemistry in 2008 from Stanford University while performing research in biophysical chemistry with Professor W. E. Moerner. In 2014, he received his PhD in Physical Chemistry from MIT under Professor Moungi Bawendi where he helped develop and apply a technique called photon-correlation Fourier spectroscopy to study the spectra of single colloidal quantum dots in solution. He has since been a postdoc at ETH Zurich with Professor David Norris working on the development of spasers and plasmonic amplifiers.

Location:Goergen 101

Refreshments will be served.