Giant Modal Gain, Amplified Surface Plasmon Polariton Propagation, and Slowing Down of Energy Velocity in a Metal-Semiconductor-Metal Structure

We investigated surface plasmon polariton (SPP) propagation in a metal-semiconductor-metal structure where semiconductor is highly excited to have optical gain. We show that near the SPP resonance, the imaginary part of the propagation wavevector changes from positive to hugely negative, corresponding to an amplified SPP propagation. The SPP experiences a giant gain that is 1000 times of material gain in the excited semiconductor. We show that such a giant gain is related to the slowing down of average energy propagation in the structur

Backilluminated ultraviolet photodetector based on GaN/AlGaN multiple quantum wells

The operation of backilluminated ultraviolet (UV)photodetector based on GaN/Al0.27Ga0.73Nmultiple quantum wells(MQWs) is reported. The MQW structure was deposited on a 1-μm-thick Al0.35Ga0.65Nbuffer layer which was epitaxied on a sapphire substrate. Coplanar Ohmic contacts were made on the top side of the MQW structure. By illuminating the Ohmic contact positions from the backside of the detector, a flat and narrow band spectral response is achieved in the UV wavelength range from 297 nm to 352 nm. The electron-heavy hole absorption in the MQW region produces the sharp long-wavelength cutoff at 352 nm and the band-to-band absorption of the Al0.35Ga0.65Nbuffer layer introduces the sharp short-wavelength cutoff at 297 nm. The polarization-induced electric fields result in a redshift of the long-wavelength cutoff. The response time is measured to be RC limited and determined to be 5 μs at a 50 Ω load

Backilluminated GaN/AlGaN heterojunction ultraviolet photodetector with high internal gain

We report on a backilluminated GaN/Al0.18Ga0.82Nheterojunction ultraviolet (UV)photodetector with high internal gain based on metal-semiconductor-metal structures. A narrow band pass spectral response between 365 and 343 nm was achieved. When operating in dc mode, the responsivity reaches up to the order of 102 A/W under weak UVillumination, which is due to enormous internal gain up to 103. The linear dependence of photocurrent on bias and its square root dependence on optical power are found and explained by a trapping and recombination model. The high photocurrent gain is attributed to trapping and recombination centers with an acceptor character induced by dislocations in GaN

Spectroscopy and carrier dynamics in CdSe self-assembled quantum dots embedded in ZnxCdyMg1−x−ySe

Time-resolved and steady-state photoluminescence,reflectivity, and absorption experiments were performed on CdSequantum dots in ZnxCdyMg1−x−ySe barriers. Studies of the capture times of the photoexcited carriers into the quantum dots and of electron-hole recombination times inside the dots were performed. Photoluminescence rise time yielded capture times from 20 ps to 30 ps. All samples exhibit fast and slow photoluminescence decays, consistent with observing two independent but energetically overlapping decays. The faster relaxation times for the sample emitting in the blue range is 90 ps, whereas for the two samples emitting in the green it is 345 ps and 480 ps. The slower relaxation times for the sample emitting in blue is 310 ps, whereas for the samples emitting in green is 7.5 ns. These results are explained on the basis of the structural differences among the quantum-dot samples

Optical Aharonov-Bohm effect in stacked type-II quantum dots

Excitons in vertically stacked type-II quantum dots experience the topological magnetic phase and demonstrate the Aharonov-Bohm oscillations in the emission intensity. Photoluminescence of vertically stacked ZnTe/ZnSe quantum dots is measured in magnetic fields up to 31 T. The Aharonov-Bohm oscillations are found in the magnetic-field dependence of emission intensity. The positions of the peaks of the emission intensity are in a good agreement with numerical simulations of excitons in stacked quantum dots.Comment: 15 page

Evaluation of the Switch From Amiodarone to Dronedarone in Patients With Atrial Fibrillation: Results of the ARTEMIS AF Studies.

BACKGROUND: Switching between antiarrhythmic drugs is timed to minimize arrhythmia recurrence and adverse reactions. Dronedarone and amiodarone have similar electrophysiological profiles; however, little is known about the optimal timing of switching, given the long half-life of amiodarone. METHODS: The ARTEMIS atrial fibrillation (AF) Loading and Long-term studies evaluated switching patients with paroxysmal/persistent AF from amiodarone to dronedarone. Patients were randomized based on the timing of the switch: immediate, after a 2-week, or after a 4-week washout of amiodarone. Patients who did not convert to sinus rhythm after amiodarone loading underwent electrical cardioversion. The primary objectives were, for the Loading study, to evaluate recurrence of AF ≤60 days; and for the Long-term study, to profile the pharmacokinetics of dronedarone and its metabolite according to different timings of dronedarone initiation. RESULTS: In ARTEMIS AF Loading, 176 were randomized (planned 768) after a 28 ± 2 days load of oral amiodarone. Atrial fibrillation recurrence trended less in the immediate switch versus 4-week washout group (hazard ratio [HR] = 0.65 [97.5% CI: 0.34-1.23]; P = .14) and in the 2-week washout versus the 4-week washout group (HR = 0.75 [97.5% CI: 0.41-1.37]; P = .32). In ARTEMIS AF Long-term, 108 patients were randomized (planned 105). Pharmacokinetic analyses (n = 97) showed no significant differences for dronedarone/SR35021 exposures in the 3 groups. CONCLUSION: The trial was terminated early due to poor recruitment and so our findings are limited by low numbers. However, immediate switching from amiodarone to dronedarone appeared to be well tolerated and safe