Aqueous Assembly of Oxide and Fluoride Nanoparticles into 3D Microassemblies.

We demonstrate rapid [∼mm/(h·L)] organic ligand-free self-assembly of three-dimensional, >50 μm single-domain microassemblies containing up to 10 individual aligned nanoparticles through a scalable aqueous process. Organization and alignment of aqueous solution-dispersed nanoparticles are induced by decreasing their pH-dependent surface charge without organic ligands, which could be temperature-sensitive or infrared light absorbing. This process is exhibited by transforming both dispersed iron oxide hydroxide nanorods and lithium yttrium fluoride nanoparticles into high packing density microassemblies.

Reduced plasma-induced damage to near-surface nitrogen-vacancy centers in diamond.

Understanding plasma etch damage on near-surface nitrogen vacancy (NV) centers in diamond is essential for preserving NV emission in photonic structures and magnetometry systems. We have developed a methodology to compare the optical properties of ensemble NV centers initially 70 nm from the surface brought closer to the surface through etching with O2 plasmas in three different reactors. We employ a conventional reactive ion etcher, a barrel etcher, and a downstream etcher.

Two-dimensional hybrid photonic/plasmonic crystal cavities.

We present a 2-D plasmonic crystal design with visible band-gap by combining a 2-D photonic crystal with TM band-gap and a silver surface. Simulations show that the presence of the silver surface gives rise to an expanded band-gap. A plasmonic crystal defect cavity with Q ~300 and mode volume ~1.

Controlled mode tuning in 1-D 'RIM' plasmonic crystal trench cavities probed with coupled optical emitters.

We present a design of plasmonic cavities that consists of two sets of 1-D plasmonic crystal reflectors on a plasmonic trench waveguide. A 'reverse image mold' (RIM) technique was developed to pattern high-resolution silver trenches and to embed emitters at the cavity field maximum, and FDTD simulations were performed to analyze the frequency response of the fabricated devices. Distinct cavity modes were observed from the photoluminescence spectra of the organic dye embedded within these cavities.