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We measured time-resolved photoluminescence from large quantum dots near a semiconductor-air interface. Far from the interface our data are consistent with dipole theory, but near the interface they question the validity of the dipole approximation.
We report on our investigation of THz emission from femtosecond filaments in argon and propose a single-shot scheme for determination of the absolute carrier envelope phase with a 2-pi ambiguity.
Positron emission tomography requires high-brightness fast-decay scintillators for coincidence counting of positron annihilation events. We demonstrate that LaF3:Ce nanocrystals show promising characteristics for that application. Scintillation response and photoluminescence lifetime below 27 ns are measured.
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.
Near-field optical spectroscopy of nanoscale Ga droplets on GaAs exhibits quenching of photoluminescence emission due to coupling with surface plasmon. Ga droplets exhibit antenna like behavior associated with a red-shift in the near-field photoluminescence emission.
Two-photon absorption induced photoluminescence of para-sexiphenyl nano-needles with high polarization and directional property was observed. The time-resolved measurement shows a very fast photoresponse and the absorption polarization selectivity of ground state.
Effects of 137Cs gamma irradiation on photoluminescent properties of CdSe/ZnS colloidal quantum dots are reported. Optical degradation was evaluated by measuring dependence of photoluminescence intensity on irradiation dose. CdSe/ZnS quantum dots show poor radiation hardness.
We experimentally report a novel asymmetrical spherical microcavity with thermal-induced deformation, in which whispering gallery modes possess not only ultra-high quality factors (Q) but also remarkably directional escape emission from the microsphere boundary.
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.
The authors report on the spectroscopy and laser results of diode pumped Pr-doped fluorides. We obtained efficient laser emission in the visible range with LiYF4, LiLuF4 and LiGdF4 crystals.
We demonstrate that a DC voltage applied on a PbS quantum dot embedded organic light emitting diode can partially quench the quantum dot photoluminescence and propose a way to avoid this quenching.
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.
In Yb3+, Er3+-codoped oxyfluoride silicate glass having composition with molar concentrations of 61SiO2-12Na2O-3Al2O3-12LaF3-12PbF2, the upconversion luminescence was greatly reduced by introducing Ce3+ ions without significantly reducing the lifetimes of lasing level.
Deterministic integration of site-controlled InGaAs/GaAs quantum dots (QDs) with photonic crystal cavities is demonstrated. Fine adjustment of QD position (within ~10 nm) and emission energy (few meV) allows construction of coupled QD systems.
We have performed low-temperature micro-photoluminescence studies on individual single-walled carbon nanotubes in magnetic fields up to 5 T and directly measured the dark-bright exciton splitting magnitude through the observation of magnetic brightening.
We present two-photon luminescence (TPL) imaging of cancer cells through a 10 times 15 times 40 mm3 miniaturized probe employing a two-axis MEMS scanning mirror and an air-core photonic crystal fiber. The combination of TPL imaging with a small probe represents a potential method of distinguishing cancerous cells in tissue for diagnosis.
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...
We compare single photon generation from quantum dots emitting into a two-dimensional photonic bandgap and a nanocavity mode using auto and cross-correlation spectroscopy. Quantum correlations are observed, even for detunings > 12 meV, indicating the presence of a remote optical coupling mechanism.
Resonant photoluminescence of Si-nanocrystals is used to determine their free-carrier absorption cross-section (sigmaFCA) at visible/near-infrared wavelengths. Rate-equation modeling, including ensemble effects, yields sigmaFCA = 7:8 times 10-18 cm2 at 895 nm. This has implications for Si-based laser design at various wavelengths.
The photoluminescence lifetime of individual, air-suspended carbon nanotubes was measured to be 57 plusmn 7 ps using femtosecond excitation correlation spectroscopy. With an excitation spot size larger than the nanotube, photoluminescence approaches a definite saturation limit.
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