Engineered liquid crystal anchoring energies with nanopatterned surfaces.

The anchoring energy of liquid crystals was shown to be tunable by surface nanopatterning of periodic lines and spaces. Both the pitch and height were varied using hydrogen silsesquioxane negative tone electron beam resist, providing for flexibility in magnitude and spatial distribution of the anchoring energy. Using twisted nematic liquid crystal cells, it was shown that this energy is tunable over an order of magnitude.

Aluminum plasmonics: optimization of plasmonic properties using liquid-prism-coupled ellipsometry.

We have established a method to quantify and optimize the plasmonic behavior of aluminum thin films by coupling spectroscopic ellipsometry into surface plasmon polaritons using a liquid prism cell in a modified Otto configuration. This procedure was applied to Al thin films deposited by four different methods, as well as to single crystal Al substrates, to determine the broadband optical constants and calculate plasmonic figures of merit. The best performance was achieved with Al films that have been sputter-deposited at high temperatures of 350°C, followed by chemical mechanical polishing.

Vanadium dioxide based plasmonic modulators.

Actively tunable metal-insulator-metal waveguides that employ vanadium dioxide films as the active medium are analyzed numerically. Vanadium dioxide exhibits strong contrast between the optical properties of its insulating and metallic phases. In particular, the large optical absorption in the metallic phase makes it straightforward to implement broadband attenuation modulators and switches, but this strong loss can also complicate the design of other types of devices.

Unity-order index change in transparent conducting oxides at visible frequencies.

We report a method for obtaining unity-order refractive index changes in the accumulation layer of a metal-oxide-semiconductor heterostructure with conducting oxide as the active material. Under applied field, carrier concentrations at the dielectric/conducting oxide interface increase from 1 x 10(21)/cm(3) to 2.8 x 10(22)/cm(3), resulting in a local refractive index change of 1.

Tunable color filters based on metal-insulator-metal resonators.

We report a method for filtering white light into individual colors using metal-insulator-metal resonators. The resonators are designed to support photonic modes at visible frequencies, and dispersion relations are developed for realistic experimental configurations. Experimental results indicate that passive Ag/Si(3)N(4)/Au resonators exhibit color filtering across the entire visible spectrum.

Electrically pumped hybrid evanescent Si/InGaAsP lasers.

Hybrid Si/III-V, Fabry-Perot evanescent lasers are demonstrated, utilizing InGaAsP as the III-V gain material for the first time to our knowledge. The lasing threshold current of 300-mum-long devices was as low as 24 mA, with a maximal single facet output power of 4.2 mW at 15 degrees C.

PlasMOStor: a metal-oxide-Si field effect plasmonic modulator.

Realization of chip-based all-optical and optoelectronic computational networks will require ultracompact Si-compatible modulators, ideally comprising dimensions, materials, and functionality similar to electronic complementary metal-oxide-semiconductor (CMOS) components. Here we demonstrate such a modulator, based on field-effect modulation of plasmon waveguide modes in a MOS geometry. Near-infrared transmission between an optical source and drain is controlled by a gate voltage that drives the MOS into accumulation.