Dissertation_DiWang.pdf (6.53 MB)
MAKING BETTER USE OF LIGHT: ADDRESSING OPTICAL CHALLENGES WITH METASURFACES
The capability of light goes well beyond illumination, yet it is so underused in our lives
because the control of light still largely relies on clumsy bulk lenses. Less than 10 years ago, a
type of revolutionary devices made of nanometer scale optical elements – metasurfaces – was
invented to control the light propagation and its energy dissipation with arbitrary degree of
freedom, at unprecedentedly small volumes (although some would argue that the advent of
metasurfaces came in the 1990s). Vast diversity of new discoveries has since been made possible,
and many more existing applications have seen significant performance enhancement with the aid
of metasurfaces.
In the scope of this work, I explore the use of a variety of metasurfaces to address several
existing real-world challenges: sensing, optical heating, and data storage. Among these, three
metasurfaces involve the world’s first two-dimensional material, graphene. I first investigate the
graphene plasmonic resonator, which have been shown to be extremely sensitive single-molecule
sensors. Graphene also has many intriguing properties in photodetection applications, such as
lightweight, ultra-wide detection band, and ultrafast response speed. I have used two different
metasurfaces to enhance the intrinsically low responsivity (sensitivity) of graphene photodetectors.
Amidst the discussion of graphene photodetectors, I show the characterization result of plasmonic
heating of metasurfaces, an essential process of the graphene photo-responsivity enhancement.
Lastly, I present a multi-functional metasurface which can be used in optical steganography,
encryption, and data storage. The proposed metasurface is compatible with large scale parallel
readout, which outperforms current Blu-ray technology in both storage capacity and readout speed
Funding
FA9550-14-1-0389
FA9550-17-1-0243
History
Degree Type
- Doctor of Philosophy
Department
- Electrical and Computer Engineering
Campus location
- West Lafayette
