Field-effect active plasmonics for ultracompact electro-optic switching Appl. Phys. Lett. 101, 121113 (2012) Quantum optical switches and beam splitters with surface plasmons J. Appl. Phys. 112, 054304 (2012) Liquid-based infrared optical switch Appl. Phys. Lett. 101, 041104 (2012) Proposal of an optical nonvolatile switch utilizing surface plasmon antenna resonance controlled by giant magnetoresistance Appl.

Doping with Be was found to be very effective for shortening of carrier lifetime in InGaAs/InAlAs multiple quantum wells (MQWs) grown at low temperature by molecular beam epitaxy. The MQW materials have carrier lifetimes controllable from a few tens of picoseconds to 1 ps in the 1.55-μm wavelength region, coupled with a large optical nonlinearity due to an excitonic feature, implying applicability to ultrafast optical devices in the fiber-optic communication. The carrier lifetime was measured by a time-resolved pump-probe method using an optical source based on a 1.535-μm semiconductor laser. We also investigated the resistivity, carrier density, and Hall mobility in the MQWs.

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We have fabricated ultranarrow InGaAs/InP buried quantum well wires by means of electron beam lithography and reverse mesa wet etching. Owing to the reverse mesa etching profile, the lateral dimension of the wires has been reduced to 10 nm. Furthermore, we investigated the optical characteristics of these wires by photoluminescence and observed, for the first time, clear dependence of luminescence wavelength upon the wire width even for wires down to 10 nm, which is well explained by the theoretical calculation. The blue-shifted shoulder structures were also observed and they were assigned theoretically to be the second quantized level.

We report on measurements of the potential profile of a GaAs/AlGaAs n-i-p-i multiple quantum well structure using a scanning Kelvin probe force microscope (KFM). Using this novel technique we directly measure with meV precision and sub-100 nm spatial resolution the potential difference between n-i-p-i layers with and without external optical excitation. The measured potential profiles, which have not been directly imaged previously, agree well with potential profiles calculated for optically excited n-i-p-i structures, but modified by band bending effects at the surface.