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An optical delay variable between 0 to 161 ps with GHz bandwidth is demonstrated in an InGaAsP quantum-well semiconductor optical amplifier and modeled by population oscillation and nearly degenerate four-wave-mixing effects for the first time.
We demonstrate that optical solitons can exist in dispersion-inverted highly-nonlinear AlGaAs nanowires. These self-localized waves are possible at very low power levels in millimeter long nanowire structures.
We have demonstrated that two-photon absorption in a 2-cm-thick bulk GaP crystal can be the mechanism for limiting the efficient generation of the ultrafast broadband THz pulses using short infrared laser pulses.
With 3-pulse wave-mixing ultrafast spectroscopy we probe simultaneously the intra and inter-band coherent dynamics in GaAs/AlGaAs quantum wells in a perpendicular magnetic field. By comparing to theory, we identify the role of inter-Landau-level coherences.
We have observed quantum interference currents by exciting exciton transitions in GaAs quantum wells. A phase shift of the current occurs when tuning the exciting photon energy from the heavy hole to the light hole exciton transition.
Spin gratings lasting longer than the carrier lifetime are measured in lightly n-doped quantum wells. In a magnetic field, precession of the grating is observed, and diffusion rates are determined by varying the grating period.
A simple first-principle analytical derivation of the permanent matrix elements of the dipole moment responsible for most of the resonant nonlinearities in III-V and II-VI semiconductors is presented.
3D FDTD is used to study the effect of surface roughening on the emission of a point source embedded in GaAs with a mirror behind the dipole. Enhancement factors of 10 : 1 are observed.
We report on strong coupling between a discrete optical mode of a high-Q micropillar cavity and single excitons of self assembled In0.43Ga0.57As quantum dots and compare the results with previous studies on In0.3Ga0.7As quantum dots.
Design and simulation are presented for a high-temperature intersubband Raman laser based on GaN/AlGaN coupled quantum wells. This laser is tunable over 3.6~5.2 mum by applying an electric field at a fixed pumping wavelength of 2.7 mum.
The 1.55 mum pulsed operation of an optically-pumped GaInNAsSb vertical-cavity surface emitting laser (VCSEL) is reported. Full temperature (10-50degC) and wavelength-dependent (1540-1560 nm) laser measurements were recorded. The annealing effect on laser performance is also shown.
Using terahertz magneto-photoconductive spectroscopy, we investigate impurity migration effects in barrier-doped GaAs/AlGaAs quantum wells. A new segregation decay rate for Si impurities in AlGaAs is determined for samples fabricated at low epitaxial growth temperature.
We present a microscopic interpretation of recent differential transmission measurements of electron spin coherence in GaAs quantum wells. We show that certain unexpected features in the beat signal can reveal finer characteristics of excitonic correlations.
We demonstrate fabrication of the first AlN-waveguide-based intersubband transition device. The device can operate at 1.3 mum, confirmed with the new waveguide-coupling measurement method. The intersubband absorption saturation in the device is also successfully demonstrated.
Fully integrated GaAs/AlGaAs passive waveguide polarisation converters realised through the use of reactive ion etch lag (RIE Lag) is reported. The devices characterised at lambda=0.9 mum produce TE-TM conversion efficiencies in excess of 96%.
The magnetic field orientation dependence of the terahertz radiation intensity from GaAs/AlGaAs modulation-doped structures with varying spacer thickness was investigated. Results are analyzed in the context of junction electric field, carrier mobility, and interface roughness.
We demonstrate a muW-level broadly tunable THz source based on parametric down-conversion in orientation-patterned GaAs pumped by femtosecond pulses from a Tm-doped fiber laser. Generated THz powers should be scalable to mW-levels with this approach.
We demonstrate efficient generation of narrow-bandwidth THz waveforms in optically-contacted multi-layer and orientation-patterned GaAs, using optical rectification of 2-4 mum, 100-fs pump pulses. THz waveforms were directly measured using two-color time-domain spectroscopy.
Phosphor-free all-semiconductor white-light devices are fabricated by coating CdSe/ZnS nano-crystals on blue/green two-wavelength LEDs for converting blue photons into red light. The LEDs are implemented by stacking two different types of InGan/GaN quantum wells.
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