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Slow down and speed-up of 180 fs pulses in an absorbing semiconductor beyond the existing models is observed. Cascading gain and absorbing sections give us significant temporal pulse shifting at almost constant output pulse energy.
We demonstrate a 2.3 mum emission at RT under quasi-CW operation from a Sb-based monolithic VCSEL. The structure is composed of 2 n-doped AlAsSb/GaSb DBR, a type-I GaInAsSb/AlGaAsSb QWs active region and a tunnel junction.
We demonstrate ultrafast self- and cross-absorption saturation and self-phase modulation based on near-infrared intersubband transitions in GaN/AlN quantum-well waveguides designed to minimize the nonlinear switching energy.
Wavelength conversion in coupled quantum wells driven by terahertz fields has been studied using a model that includes the effects of band structure, excitons and intersubband transitions. Good agreement is achieved with published experimental data.
We present time-resolved photoluminescence on InGaN/GaN multiple-quantum well LEDs grown on nonpolar and semipolar bulk GaN substrates and investigate increasing indium concentrations toward higher power, longer wavelength light emitters.
Time-resolved electro-absorption is reported for the first time in a GaInNAs quantum well p-i-n waveguide at 1.3 mum. A recovery of 55 ps demonstrates the potential for optical modulator devices.
Optimization studies of InGaN quantum wells light emitting diodes employing SiO2/polystyrene microlens arrays are conducted. The use of microlens arrays leads to increase in light extraction efficiency by 2.7-times, in agreement with simulation.
Micro-photoluminescence from GaN/InGAN multiple quantum wells embedded in a nano-pillar structure with a diameter of 300 nm is characterized. The emission spectrum shows a blue shift of 68.3 meV in energy due to strain relaxation.
We demonstrate the reduced spectral blue shift in increasing injection current of an InGaN/GaN quantum-well light-emitting diode with prestrained growth and show that this effect is stronger when the prestained GaN barrier layer is thinner.
We have studied the crystal orientation effect on optical anisotropy in InGaN/GaN quantum-well light-emitting diodes. The absolute value of the anisotropy is found to increase rapidly with increasing crystal angle.
We report novel single-crystalline (In)GaAs nanoneedles with 2~5 nm tips, smooth 6-9deg taper angles and lengths up to 3-4 mum, grown aligned to [111] orientation on Si substrates. Bright photoluminescence is obtained from quantum-well nanoneedles.
A hexagonal array of sub-micron sized holes was fabricated on InGaN/GaN quantum-well light-emitting diodes using nanoimprint lithography. Photoluminescence measurement confirms that light extraction of the LED was enhanced with two-dimensional photonic crystal patterns.
We design, fabricate and demonstrate a hybrid nanocrystal/patterned p-i-n device that utilises fluorescence energy transfer and exhibits a three-fold increase of the measured photocurrent compared to its bare p-i-n counterpart.
We report on the coherent coupling between surface plasmon polaritons and quantum well excitons in a hybrid metal-semiconductor nanostructure. The coupling is probed by angle-resolved low temperature spectroscopy and analyzed within a coupled oscillator model.
High-power diode lasers with heavily-strained In(Al)GaAsSb type-I quantum-well active region emitting at 3.1 mum at room temperature are reported. Devices operate in continuous-wave regime with output power above 200 mW and 80 mW at 250 K and 285 K, correspondingly.
The quantum-confined Stark effect demonstrated in Si-Ge/Ge quantum wells promises integration of optics with silicon ICs. Using photocurrent, tunneling resonance and nonparabolicity, we propose more accurate values of key parameters for device design.
Raman coherence between heavy-hole and light-hole excitons in quantum wells is isolated in an alternative spectrum and contributions from single exciton and correlated two-exciton states are studied experimentally and theoretically by excitation with different polarizations.
Self-phase modulation was observed in GaAs/AlGaAs superlattice-core waveguides that were quantum well intermixed by ion implantation. The band gap was blue-shifted by 68 nm and the Kerr effect was suppressed by 67% after intermixing.
We present studies of 2D indirect excitons in an in-plane trap created by a laterally modulated gate voltage. Our data indicates an effective evaporative cooling of excitons in the elevated trap regime. We also observed narrow PL lines which correspond to the emission of localized and delocalized states of the indirect excitons in the trap. The homogeneous line broadening due to interaction increases...
Using a two-color, three-pulse differential transmission technique, we manipulate nonlinear optical processes of electron spins in a modulation-doped CdTe quantum well through exciton injection. The spin manipulation takes place without optical spin rotation.
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