Professor SUN Handong

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Research Focus

Optoelectronic materials & devices, Semiconductor physics; Optical spectroscopy; Nano-materials & Technology, etc.

Detailed Research Interests

Our research theme exists at the interface between optical physics and material science, i.e. light-matter interaction. Besides the physical interest, potential application is always our strong driving force for the research. Current research activities will focus on but not limited to the following topics.


Optical spectroscopic characterization

Optical spectroscopy provides a powerful tool for understanding the physical properties of a wide range of condensed matters. The investigated materials cover from the traditional inorganic semiconductors (bulk, quantum dots, wires and wells), organic semiconductors to artificial materials (organic/inorganic hybrid structures and composites). We are interested in the investigation of electronic structures, various elemental excitations and their dynamic process in semiconductor structures; energy transfer; charge separation and transport in various organic blends and organic/inorganic composites. The clarification of the underlying physics is very important for both fundamental physics interest and development of optoelectronic devices.


Optoelectronic Devices

On the basis of understanding the optical properties of a wide range of materials, we will dedicate to develop useful optoelectronic devices. For example, we will seek to utilize wide bandgap material systems to develop surface emitting lasers for the important blue-green to ultraviolet wavelength range. Taking advantage of the unique material properties inherent to wide bandgap materials, especially high excitonic oscillator strength and high exciton binding energy, it is expected to directly generate solid state lasers in blue-green to UV wavelength range with high power and high beam quality for a wide range of applications. The relevant material processing techniques will be further developed to form high quality microcavity in the strong coupling regime, which will makes it possible to experimentally explore the exciting physics of Cavity Quantum Electrodynamics and new concept devices-room temperature polariton lasers.


Plasmonics Optics

In practical light emitting devices, the overall efficiency depends on not only the internal quantum efficiency of the active materials but also on the external conditions. Photonic crystals and surface plasmon coupling are two effective approaches to improving the light extraction rate from the active materials. Surface plasmon polaritons are created via the coupling of light to the motion of the conduction electrons at a metallic interface. Enhanced emission from the surface plasmons is possible due to the large density of states in their dispersion diagram. Excitation of surface plasmon polaritons within the metal at nano-scale can create strong local optical fields, which can be exploited for numerous applications, such as single-molecule fluorescence, surface-enhanced second harmonic generation and surface-enhanced Raman scattering etc. Photonic devices at nano-scale are possible because light can be confined this way to dimensions below the diffraction limit of light. More over, it has been shown that the hybrid metal/dielectric layers with particular geometry display interesting transmission properties for electromagnetic waves including wavelength selectivity, particular emission angle distribution and even negative refractive index. Therefore the related research is expected to have great impact on photonics and biomedical detection.


Applications of Photonics

The combination of photonics and biotechnology may provide some of the most exciting scientific and commercial prospects. Successful commercial examples include corrective eye surgery and dentistry by lasers etc.. New applications have also been found for lasers in biomedical imaging, optical tomography and optical biochips which use light to excite specially designed fluorescent chemicals that can reveal important features about each cell such as how it responds to a drug or whether or not it is diseased. However, there are still a lot remained unknown in the interaction between photons and bio-molecules, and big space exist in the use of light for both diagnostic purposes and as a powerful tool for manipulating material on cellular and sub-cellular length scales. We are interested in intra- and inter biomolecules-photo-driven biological processes with the aim of understanding how nature efficiently converts solar energy to perform critical biological functions. The tools related to the research include FRET based probes, anisotropic spectroscopy, surface-enhanced Raman scattering, time-resolved fluorescence and absorption, selectively excited fluorescence etc. The combination of these techniques and nano materials (e.g. carbon nanotubes and plasmon resonant nano-metals etc.) can be used to generate nanoscale biosensors. Such research will be undertaken by synergic cooperating with chemists and biologists.






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