We present the first experimental demonstration of zero backscattering from nanoparticles at optical frequencies as originally discussed by Kerker et al. [ Kerker , M. ; Wang , D. ; Giles , C. J. Opt. Soc. A 1983 , 73 , 765 ]. GaAs pillars were fabricated on a fused silica substrate and the spectrum of the backscattered radiation was measured in the wavelength range 600-1000 nm. Suppression of backscattering occurred at ~725 nm, agreeing with calculations based on the discrete dipole approximation. Particles with zero backscattering provide new functionality for metamaterials and optical antennas.

This letter presents a type of infrared detector named the nBn detector. The nBn design essentially eliminates Shockley-Read-Hall generation currents. The result is greatly reduced dark current and noise, compared to other midwave infrared detectors, such as p-n photodiodes. This enables the nBn to operate at background-limited infrared photodetection conditions at significantly higher temperatures than conventional midwave infrared detectors and have greater detectivity near room temperature. The nBn is demonstrated in InAs and InAsSb materials, exhibiting cutoff wavelengths of 3.4 and 4.2μm, respectively.

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We have constructed and characterized several optical microring resonators with scale sizes of the order of 10 microm. These devices are intended to serve as building blocks for engineerable linear and nonlinear photonic media. Light is guided vertically by an epitaxially grown structure and transversely by deeply etched air-clad sidewalls. We report on the spectral phase transfer characteristics of such resonators. We also report the observation of a pi-rad Kerr nonlinear phase shift accumulated in a single compact ring resonator evidenced by all-optical switching between output ports of a resonator-enhanced Mach-Zehnder interferometer.

The oxidation of GaN at room temperature was investigated using x-ray photoemission spectroscopy. The onset of oxidation is observed at 105 Langmuir (L=10−6 Torr s) of oxygen exposure. This is seen both in changes in the percent composition of oxygen and in shifts in the core spectrum of Gallium. The oxidation saturates at an exposure of 108 L. Detailed core level analysis shows that at this exposure most of the surface Ga atoms have been oxidized. The results indicate that the oxidation of GaN is a kinetically limited process restricted to the surface and the underlying bulk is not strongly perturbed. This is in sharp contrast with GaAs where oxidation begins at the same level of exposure and then continues for all further exposures as subsurface layers are oxidized.