Invited Paper
Practical Nanophotonics with Plasmonic Ceramics

In recent years, two avenues of nanophotonics, namely plasmonics and optical metamaterials (MMs), have seen an explosion of novel ideas and designs that could provide breakthrough devices and exotic functionalities. However, the fields of plasmonics and MMs have long been dominated by noble metals, which lack both tunability of their optical properties and CMOS-compatibility. Plasmonic ceramic materials, such as transition metal nitrides and transparent conducting oxides (TCOs), offer a solution to these problems and could enable consumer photonic devices across many fields including flat photonic components (lenses, wave-plates, spatial light modulators), localized surface plasmon resonance (LSPR) applications, integrated optical circuitry, and metamaterials-based light sources and solar cells. Among the transition metal nitrides, titanium nitride (TiN) has shown promise as a plasmonic material in the visible and near infrared. TiN is a plasmonic ceramic material having optical properties resembling those of gold. Unlike gold however, TiN is CMOS-compatible, mechanically strong, and thermally stable at higher temperatures. Additionally, TiN exhibits forms low-index surfaces with surface energies that are lower than those of the noble metals, facilitating the growth of smooth, ultra-thin crystalline films that are useful crucial in constructing low loss, many high-performance plasmonic and MM devices including waveguides and hyperbolic MMs (HMMs). Hyperbolic MMs have been shown to exhibit exotic optical properties, including extremely high broadband photonic densities of states (PDOS), which are useful in quantum photonics applications. We demonstrated that an epitaxial superlattice with TiN as a plasmonic component works as a high quality HMM that provides a higher PDOS enhancement than metal-based HMMs. We also showed that TiN is a successful material for integrated plasmonic applications, with waveguiding structures achieving surface plasmon polariton propagation lengths exceeding 5 mm. Such structures can easily be integrated with plasmonic modulators, which use the tunability of TCOs to attenuate a SPP wave. In this talk, various plasmonic ceramic materials will be discussed for nanophotonic devices with enhanced flexibility and performance across many avenues of nanophotonic research.

aeb@purdue.edu