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We used pump-probe technique to investigate recombination dynamics of photogenerated carriers in photodiodes consisting of InAs/GaInSb W-structured superlattices. Recombination time constants of 1.6 ns and 10 ns were measured under high and low powers, respectively.
This paper discusses the optical characteristics of a nonpolar a-plane InGaN/GaN quantum well (QW) with different indium compositions, QW well widths, and injection carrier densities. We find that the larger indium composition and smaller well width make the energy separation of |Yrang-like state to |Zrang-like state larger, and as a result enhance the polarization ratio of light. However, the polarization...
We realize a new scheme for making a direct contact to a two-dimensional (2D) nanorod LED array using the oblique-angle deposition. More importantly, we demonstrate highly efficient carrier injection into the nanorods.
Novel approach to improve light extraction efficiency of InGaN-based light emitting diodes with polydimethylsiloxane concave microstructures arrays was demonstrated, which leads to enhancement of extraction efficiency by 1.60-times in good agreement with simulation.
We demonstrated a GaN-based p-i-n photodiode by inserting a thin low-temperature-grown-GaN layer between p-type Al0.2Ga0.8N window and intrinsic GaN layer. As compared with control device, our demonstrated one can achieve 3 fold bandwidth-efficiency-products improvement.
We demonstrate first observations of slow-light enhanced three-photon absorption(ThPA) in photonic crystal waveguides.The injected pulses demonstrate self-phase modulation(SPM) with scalings deviating from ng2(SPM) and ng3(ThPA).A thorough analysis suggests pulse compression leading to increased peak powers.
For similar GaSb substrate thickness, flip-chip mount bottom emitting LWIR LED device has higher light intensity than top emitting device. Enhanced emission is attributed to better cooling and reflection of light from anode metal surface of the device.
Regrowth-free gain-coupled GaSb-based DFB lasers suitable for gas sensing were fabricated. Threshold currents for 2.4 mum emission of 400 mum-long DFB devices were 45 mA with a total output power of nearly 11 mW in CW operation at 20degC.
We report on the use of confocal thermoreflectance for accurate surface temperature measurement of transparent LEDs. Confocal thermoreflectance effectively suppresses light from beneath the LED surface, compared to widefield measurements, for a red GaP LED.
Simultaneous high modulation speed and high modulation efficiency operation of a two-electrode tapered laser is reported. 1 Gb/s direct data modulation is achieved with 68 mA applied current swing for a 0.95 W output optical modulation amplitude.
Electrical properties of low-temperature grown Mg-modulation-doped InGaN/GaN superlattice (MD-SLS) for green light-emitting diodes (LEDs) are investigated. Room-temperature Hall effect measurements indicate that the MD-SLS has conductivity comparable to that of high-temperature grown p-type GaN. The light output intensity of green LEDs with the p-InGaN/GaN MD-SLS is approximately doubled as compared...
We demonstrate a novel four-well injectorless design with short wavelength (5.5 mum) and room temperature operation utilizing highly strained Ga0.35In0.65As/Al0.70In0.30As (0.8/-1.5%) quantum wells.
We investigated the effects of prestrained layers on piezoelectric fields and indium incorporation in blue-emitting InGaN/GaN quantum wells by using reverse-biased electroreflectance spectroscopy. We compared two sets of samples, which have identical structures except an insertion of an additional UV quantum well at the bottom of the blue-quantum well. Indium composition of quantum wells with the...
We have succsessfully developed blue-violet laser diodes having the world's highest output power of 450 mW by introducing a novel facet coating structure, reducing the internal loss in devices, and making a cavity length long.
Phonon-assisted anti-Stokes fluorescence has been observed in GaN film grown on Si (111) substrate. The donor-acceptor pairs and bound excitons have played primary roles in the generation of anti-Stokes fluorescence.
We present time resolved photoluminescence supported by kldrp modeling of type II quantum dots. In the measured spectra two effects were observed; an initially fast decay time rises dramatically as the number of carriers is depleted, which reduces the optical matrix element, and at the same time, a strong red shift of the emission wavelength is observed.
Yb3+:(YGd2)Sc2(GaAl2)O12 disordered ceramic has been fabricated. 2.9-W average power with an optical-to-optical efficiency of 44% was achieved in a continuous-wave operation. 112-fs pulse duration with 860-mW average power was also achieved in a mode-locked operation.
Wavelength selective switch using GaInAs/InP MQW variable index arrayed waveguides have successfully demonstrated. The demultiplexed wavelength light could be exchanged the output ports by changing the refractive index of arrayed waveguides by using thermo-optic effect.
Distinctive indium-tin-oxide nanorods are demonstrated using glancing-angle deposition. The nanostructured material exhibit enhanced transmission and is employed to enhance the light-output-power of GaN/InGaN vertical-injection light emitting diodes by 20% at an injection current of 350 mA.
The effects etching depths of nanohole arrays close to or penetrate the quantum well structures are studied. Our results suggest that when the hole depth is close to the quantum well region, the surface states pinning reduces the band bending and leads to a blue shift of the emission spectrum. When the hole penetrates the quantum well region, similar effects are observed but are due to the strain...
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