Surface plasmon based photonic (or plasmonic) circuits merge electronics and photonics at the nanoscale, creating the ability to combine the superior technical advantages of photonics and electronics on the same chip. Recent work has demonstrated their remarkable applications in subwavelength optics, data storage and transmission, light harvesting and generation, and microscopy, as well as bioapplications. Plasmonics has become one of the most intensive research subjects in recent years, and much effort has been made to develop novel and efficient waveguiding structures and plasmonic materials. We will first review some major progress in subwavelength plasmonic waveguides and plasmonic materials. Then, focusing on the applications of a class of promising alternative plasmonic materials, transparent conducting oxides, we will introduce some of our up-to-date study, especially on electro-absorption modulators and beam steering.
We explore tunable plasmonic metamaterials for electro-optic modulator applications based on ITO-based multilayer
structures. Two different structures are investigated, and modulation depth up to 38.8% can be achieved. Preliminary
results are presented for the real time response of an ITO/electrolyte gel/doped Si modulator. Furthermore, another
modulator configuration is investigated by substituting electrolyte gel by high-k dielectric material (HfO<sub>2</sub>).
We demonstrate greatly enhanced light absorption by monolayer graphene over a broad spectral range, from visible to
near infrared, based on attenuated total reflection (ATR). The designed structure consists of two dielectric media and
monolayer graphene between them. Up to 42.7% light absorption has been achieved by this structure. Moreover, when
applying electrolyte gel, electric double layers are formed at the graphene-gel interface, which leads to the change of
graphene’s electrical properties as well as optical properties. As a result, light absorption of graphene can be manually
modulated. This design may help build electro-optic modulators for applications in communications, sensing and
Recent research on epsilon-near-zero (or index-near-zero) materials has revealed their promising applications in
optoelectronics. We explore a novel waveguide structure, namely “epsilon-near-zero-slot waveguide”, by utilizing
transparent conducting oxides as the active medium, which can be tuned between epsilon-near-zero and epsilon-farfrom-
zero by accumulation carriers, resulting in sharp effective index change. We propose laser beam steering by taking
advantage of this epsilon-near-zero-slot waveguide structure. With about 60°steering angle being achieved, this
waveguide structure has the advantages of ultra high speed and compact dimension, as well as easy fabrication.