Research

My group’s research interests span the electromagnetic spectrum from the millimeter waves (mmWaves) to the terahertz (THz) frequencies. Until recently, this band has not been fully exploited due to the under-performing hardware. For example, detectors were not sensitive enough and sources were too weak. However, recent advances in semiconductor technology and nanofabrication techniques have turned the tide and unveiled the great potential of this spectrum with new exciting applications in security monitoring, biomedical imaging as well as high data rate wireless communications.

Here is some of the past and current work :

• Non-line-of-sight Imaging: Can we see around obstacles from a single viewpoint?  We are using millimeter/THz waves to augment vision to non-line-of-sight (NLoS) areas. By understanding the interaction of THz waves with common building surfaces, we can inverse the propagation path and reconstruction images of both LoS and NLoS objects.  Being able to see around obstacles will enable applications in rescue and surveillance missions, autonomous navigation, simultaneous localization and mapping, and wireless communications.

• Augmented Reality to See Around Obstacles: THz signals are invisible to the human eye. How can we then visualize NLoS objects? We are interested in using augmented reality (AR) methods to enable the user to visualize the NLoS information from THz imaging systems. Below is a short video that demonstrates the visualization power of AR for NLoS imaging.

• Imaging Systems: We bring together algorithms and hardware design to form unique imaging and sensing systems. For example, a THz camera is comprised of various optics, a large-format focal plane array for image formation, ultra-fast diodes for THz signal detection, read-out circuit that collects DC signals from more than 5,000 antenna pixels. We are also interested in lensless imaging systems that will allow wearable high spatial resolution imaging. The 2D geometry of lensless imaging will enable wearable systems or imagers that can be easily integrated on vehicles or other irregular surfaces.

• On-chip antennas: Novel topologies for broadband, ultrasensitive detectors. Such antennas have to optimize radiation pattern as well as impedance matching with sensing devices (i.e. diodes, mixers, transistors, etc.)

• Computational Methods for mmW/THz Imaging Systems: Modeling mmW/THz imaging systems results in electrically large problems that require carefully chosen approximations to estimate the response of the system. Geometrical optics is typically not valid in mmW/THz and we need to account for complex phenomena including scattering, diffraction from rough surfaces and edges.

• Non-contact device and circuit testing: A novel testbed that allows S-parameter measurements without contacting the device under test and without residing to expensive and fragile contact probes.