InGaAsP photonic crystal slot nanobeam waveguides for refractive index sensing

Results are presented on the use of InGaAsP photonic crystal nanobeam slot waveguides for refractive index sensing. These sensors are read remote-optically through photoluminescence, which is generated by built-in InGaAs quantum dots. The nanobeams are designed to maximize the electromagnetic field intensity in the slot region, which resulted in record-high sensitivities in the order of 700 nm/RIU (refractive index unit). A cavity, created by locally deflecting the two beams towards each other through overetching, is shown to improve the sensitivity by about 20%

Heterogeneous integration of III-V optoelectronic devices on silicon

Silicon has been proven to be an excellent platform for photonics. However, active functionality and in particular tight generation directly from silicon remains difficult Therefore we developed a die-to-wafer bonding based approach for integrating HI-V materials directly on silicon in a cost-effective way, which does not compromise the quality of the materials. In this paper we will illustrate the integration technology developed and several devices fabricated

Picosecond Time-Resolved Bleaching Dynamics of Self-Assembled Quantum Dots

Picosecond bleaching dynamics of vertically stacked self-assembled quantum dots (QDs) is investigated by means of time-resolved pump-probe differential reflection spectroscopy (TRDR) at room temperature (RT). We observe that the absorption spectrum, which represents the QD density of states at RT, is strongly shifted with respect to the photoluminescence spectrum. This shift can not be interpreted by carrier emission and re-trapping alone. TRDR allows us to study the dynamics of the pump generated carriers within the QDs. From the time-resolved measurements, we detect that the bleaching decay time has a strong energy dependence and is dominated by radiative and nonradiative recombination at low energy and by carrier emission at high energy

Synthesis of barbituric acid doped carbon nitride for efficient solar-driven photocatalytic degradation of aniline

A series of barbituric acid doped carbon nitride (CN-BA) photocatalysts were successfully prepared by copolymerizing dicyandiamide with barbituric acid (BA). Under AM1.5 simulated sunlight, CN-BA photocatalysts exhibit enhanced photocatalytic activity compared to pure carbon nitride for the degradation of aniline. The highest activity is obtained with 2% doped CN-BA photocatalyst. Results: on the photodegradation of aniline indicate that for the optimized CN-BA photocatalyst, the concentration of aniline solution was reduced gradually from 16 mg/L to 1.354 mg/L in 2 h. This corresponds to a 6 times higher photodegradation efficiency than pure carbon nitride samples. The enhanced photocatalytic activity of CN-BA relies on the enhanced surface area, the higher light absorption and the reduced recombination of the photo-generated electron-hole pairs. This interpretation results from multiple characterizations with EPR, BET, N-2 adsorption, Solid-state C-13 NMR, UV-vis DRS, FESEM, and TEM. Under simulated sunlight irradiation, CN-BA is excited and generates electron-hole pairs. The photo generated electrons in the CN-BA conduction band react with the molecular oxygen to form O-center dot(2)-. Part of the O-center dot(2)- transforms into (OH)-O-center dot, which further oxides aniline. Meanwhile, photo-generated holes in the valence band of CN-BA can benefit to the formation of (OH)-O-center dot or directly oxide aniline. (C) 2017 Published by Elsevier B.V

Atomic scale analysis of intermixing, segregation and decompostion during self assembly of nanostructures

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