The clinical impact of microplasma jets on rabbit eyes infected by Candida albicans has been investigated. Arrays of such jets produce low-temperature plasma micro-columns suitable for ophthalmic therapeutics and fungal infections, in particular, and the technology is capable of being scaled to surface areas of at least 10 cm2. Keratitis was induced in the right central corneas of rabbits, whereas the left eyes served as a normal group. The rabbits were divided into the plasma non-treated group (control) and plasma treatment group. Histologic analyses of both groups showed marked reductions in the thickness, angiogenesis, and opacity of all rabbit corneas following plasma treatment. Indeed, for treatment times beyond 14 days, infected eyes exhibited no significant differences from the normal group. Healing of rabbit eyes infected by Candida albicans apparently proceeds by disrupting corneal epithelial proliferation, and by reducing fibrotic changes in the stroma. This study demonstrates that low-temperature plasma jets are remarkably effective in healing Candida albicans-infected corneas, thereby providing a promising medical treatment option for keratitis.

A plasma photonic crystal operating as a notch filter at 157 GHz ( o) has been demonstrated. Comprising a 5 × 10 array of microplasma jets, having a pitch and jet diameter of 1 mm and 400 μm, respectively, this two-dimensional plasma crystal exhibits an unexpectedly narrow stopband (Δ o = 1.0 GHz FWHM = 0.6 % o) and a maximum, time-averaged attenuation of 5 % at 157.0 GHz. Simulations accurately predict the position of line center, and the assumption of a time-averaged electron density of 3 × 10 13 cm -3 is necessary for the predicted magnitude of peak attenuation (at 157 GHz) to be in agreement with experiment. Reconfigurable plasma photonic crystals, synthesized from microcavity plasmas and providing electromagnetic functionality in the 100 GHz -1 THz spectral region (300 μm ≤ λ ≤ 3 mm), are now feasible.

Wall-plasma interactions have been observed for spatially-periodic microplasmas generated in 300-700 µm wide channels fabricated in nanoporous alumina. Examination of Ne microplasma discs produced in a standing-wave pattern in Al 2 O 3 channels illustrates the competition between electron production at the sheath-wall interface and loss by recombination in an atmospheric pressure background. Two topologies of the microplasma arrays are observed. For channel widths (d) less than 450 µm, the microplasmas are generally centered in the channel and sustained by electron generation at both plasma sheath/channel wall interfaces, presumably including the release of charge residing in the hexagonal alumina pores. As d is progressively increased from 300 to 450 µm, the microchannel plasma crosssection is gradually transformed from circular to elliptical, and its surface area declines by as much as 50% so as to minimize e − losses to the background gas. Increasing d above ~450 µm abruptly switches the topology to one in which plasmas having a triangular crosssection attach to one of the channel walls in a pattern that alternates along the channel axis. Microfabricating trapezoidal cross-section channels into complex geometries, including the Cornu spiral and intersecting linear arrays, also reveals dynamic behavior in the propagation of microplasmas. For a common spiral structure, observations of plasma expansion show the wavefront propagates over the corrugated surface or within the channel with radial and azimuthal velocities of 3 ± 1 km s −1 and 8 ± 1.5 km s −1 , respectively. Plasma formation is initiated in each ring of the spiral through electron seeding by streamers propagating radially outward at velocities approaching 200 km s −1 . In addition to electrostatic charge-mediated variations in the mean separation between adjacent microplasmas, the time-dependent interference between two 1D microplasma arrays has been observed during plasma expansion. Reproducible ignition of a microplasma ensemble along ridges micromachined into channels near the intersections of two linear arrays has also been realized. The results reported here demonstrate that microchannels with the walls overcoated with any of a variety of materials provide a promising platform for examining in detail the interaction of low temperature plasma with a surface of arbitrary composition and topography.

Direct coupling of the optical field in a ∼244 nm thick, CdSe/ZnS quantum dot film to an optical fiber has yielded lasing in the red (λ ∼ 644 nm) with a threshold pump energy density < 2.6 mJ cm−2. Comprising 28–31 layers of ∼8 nm diameter quantum dots deposited onto the exterior surface of a 125 μm diameter coreless silica fiber, this free-running oscillator produces 134 nJ in 3.6 ns FWHM pulses which correspond to 37 W of peak power from an estimated gain volume of ∼4.5 × 10−7 cm3. Lasing was confirmed by narrowing of the output optical radiation in both the spectral and temporal domains, and the laser beam intensity profile approximates a top hat.