P.-C. Ku

Research Interests

Our research focuses on "Energy Efficient Optoelectronics". For example, we are interested in how to reduce the laser threshold, how to increase the efficiency of light-emitting diodes and solar cells, how to efficiently transmit the data while maintaining the security, and how to reduce the power requirement for nonlinear optical devices.

To achieve this goal, we investigate nanophotonic devices and related nanofabrication techniques. In other words, we study and control light-matter interactions in nanoscale materials and structures, aiming to improve efficiencies of optoelectronic devices and systems. The applications are far reached with examples including energy efficient lighting and renewable energy, data communication and signal processing, data storage, display, biomedical diagnosis, and quantum information science. Our current research can be divided into three interrelated thrusts: gallium nitride optoelectronic devices, nano-optoelectronic devices, and nano materials synthesis, processing, and integration.

Gallium Nitride Optoelectronic Devices

Gallium nitride (GaN) and related nitride semiconductors, AlN and InN, exhibit direct bandgaps across the ultraviolet, visible, and near-infrared spectrum. Furthermore, they exhibit large exciton binding energy and oscillator strength. Therefore nitride semiconductors can find applications ranging from energy efficient lighting to solar cells, display to data storage, and biomedical diagnosis to quantum information processing. In this thrust, we study GaN and plasmonic nanostructures in the following devices.

Visible light-emitting diodes (LEDs) and applications
InGaN quantum dot devices
Nitride based solar cells

NSSP green LED InGaN QDs Spiralight

Nano-Optoelectronic Devices

Photons are proven information carriers that exhibit large capacity and span long distance. However, unlike electrons, photons cannot be easily stopped or manipulated due to their lack of charges. In addition, the wavelengths of visible and infrared photons are hundreds or thousands of times more than the de Broglie wavelength of the electron, making the photons increadibly difficult to confine to the nanoscale. In this thrust, we study semiconductor and metallic nanostructures in order to achieve the following devices.

Nanoscale (sub-wavelength) semiconductor lasers
Slow light devices and optical buffers
Nanoscale nonlinear optical devices

slow light TeO2 waveguide

Nano Materials Synthesis, Processing, and Integration

To realize or mass produce any of the nanophotonic devices mentioned above, our group is actively pursuing novel nanofabrication techniques in the following three areas.