H. Z. Song

Site-controlled photoluminescence at telecommunication wavelength from InAs∕InP quantum dots

We fabricated ordered InAs∕InP quantum-dot (QD) arrays using atomic-force-microscopic oxidation, wet etching, and regrowth by metalorganic chemical vapor deposition. The QDs exhibit single-dot photoluminescence peaking at wavelengths ranging from 1.22 to 1.45μm, mostly matching the telecommunication band of optical fibers. The site dependence of single peaks indicates the site controllability of single-dot light emitters, which might be useful in quantum information processing.

Polarization-dependent shift in excitonic Zeeman splitting of self-assembled In0.75Al0.25As /Al0.3Ga0.7As quantum dots

We report optical spectroscopic results of a single self-assembled

Few-Electron Molecular States and Their Transitions in a Single InAs Quantum Dot Molecule

{\mathrm{In}}_{0.75}{\mathrm{Al}}_{0.25}\mathrm{As}∕{\mathrm{Al}}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}

High-speed and temperature-insensitive operation in 1.3-µm InAs/GaAs high-density quantum dot lasers

quantum dot. The polarization-dependent shift of the Zeeman splitting in a single InAlAs quantum dot (QD) has been observed. The induced Overhauser field is estimated to be

Effect of carrier transport on modulation bandwidth of 1.3-µm InAs/GaAs self-assembled quantum-dot lasers

\ensuremath{\sim}0.16\phantom{\rule{0.3em}{0ex}}\mathrm{T}

Nuclear and excitonic spin polarization formed using cross-linearly polarized pulse pair via half-localized state in a single self-assembled quantum dot

in this InAlAs QD and the magnitude is shown to be controllable by the degree of circular polarization of excitation light.

Low Power Consumption Operation of a 1.06-μm-Wavelength Single-Mode Laser for Efficient Second-Harmonic-Generation Green Laser Modules

We study electronic configurations in a single pair of vertically coupled self-assembled InAs quantum dots, holding just a few electrons. By comparing the experimental data of nonlinear single-electron transport spectra in a magnetic field with many-body calculations, we identify the spin and orbital configurations to confirm the formation of molecular states by filling both the quantum mechanically coupled symmetric and antisymmetric states. Filling of the antisymmetric states is less favored with increasing magnetic field, and this leads to various magnetic field induced transitions in the molecular states.

1.3 µm InAs/GaAs high-density quantum dot lasers

Temperature-insensitive 10.3-Gb/s operation under fixed driving condition was demonstrated using directly-modulated InAs/GaAs high-density quantum dot lasers, maintaining an Ethernet mask margin of 48 % up to 100 °C. 20-Gb/s direct modulation has also been demonstrated.

Mechanism of Quantum Dot Formation by Postgrowth Annealing of Wetting Layer

We newly modeled the modulation bandwidth of 1.3-µm quantum-dot lasers and analyzed experimental results. The carrier transport through the active layers was found to affect significantly the modulation bandwidth with increasing stacking-number of quantum-dot layers.

Characterization of g‐Factors in Various In(Ga)As Quantum Dots

The oscillations of excitonic and nuclear spin polarizations in an optically pumped single self-assembled In0.8Al0.2As/Al0.35Ga0.65As quantum dot (QD) were clearly observed under the excitation of a wetting layer edge at B=5 T. This indicates that an exciton pair with opposite spins is alternatively created via the half-localized state only by changing the delay time between cross-linearly polarized pulse pair. Furthermore, periodic modulation of Zeeman energy synchronizes the degree of circular polarization of photoluminescence from a single QD, indicating that the Overhauser field follows the optically created electron spin polarization in half-localized states of a QD, and the half-localized state in a QD consists of a confined electron in a discrete state and hole in the continuum state.