Purcell Effect and Beaming of Emission in Hybrid AlGaAs Nanowires with GaAs Quantum Dots

Abstract

Control of directionality of emissions is an important task for the realization of novel nanophotonic devices based on nanowires. Most of the existing approaches providing high directionality of the light emitted from nanowires are based on the utilization of the tapered shape of nanowires, serving as nanoantenna coupling with the light waveguided in nanowire and the directional output beam. Here we report the beaming of the emitted light with wavelength near 800 nm by naturally formed core-shell AlGaAs NW with multiply GaAs quantum dots (QDs) diameter 30 nm and height 10 nm, while the diameter of NW 130 nm, what does not support efficient emission into waveguided modes, including the mode HE11. Experimental measurements show that intensity of emission for directions in the vicinity of the axis of NW is about two orders of magnitude higher than for perpendicular directions. The developed theoretical approach allowed us to calculate the probability of spontaneous emission for various directions and into waveguided modes and showed that highly directional radiation can be provided by the intrinsic emission properties of cylindrical NW. Our results suggest that for the small diameter of NW, directional emissions are associated with an TM0 leaky mode (when electric field oriented in axial direction) and therefore manifests in an existence of axial electric dipole transitions in quantum dots.

Formation of InGaAs quantum dots in the body of AlGaAs nanowires via molecular-beam epitaxy

“…In the case of NWs lying on the surface, radiation from QDs prevails, but no significant signal from AlGaAs NW or InGaAs QW is observed. This correlates well with the theoretical predictions described in [23,24], according to which, for emitters with a longer wavelength, the anisotropy in the radiation is suppressed;therefore, for radiation from InGaAs QDs emitting in the range 850−900 nm, the anisotropy is less pronounced.…”

Modeling of spontaneous emission in presence of cylindrical nanoobjects: the scattering matrix approach

“…1b, although the authors of Ref. [6] attribute the guided mode as HE 12 whereas we conclude that it is EH 11 mode.…”

Спонтанная Эмиссия В Утекающие Моды Нанопроводов

“…Из выражений (4) для цилиндрических волн можно получить угловую зависимость от полярной координаты φ для плотности потока энергии электромагнитных полей, образованных различными линейными комбинациями цилиндрических волн с m = ±|m|, эти зависимости различны для TМ-и TE-поляризованных полей. Воспользовавшись этим анализом и полученным выражением (18), можно определить, какая часть спонтанного излучения эмиттера уходит в определенный телесный угол do = sin θdθdφ :…”

“…Кроме этого, при анализе процессов излучения в нанопроводе иногда ограничиваются описанием взаимодействия эмиттера с волноводными модами, игнорируя излучение в свободное пространство (вытекающие моды), что, возможно, связано с наличием фундаментальной волноводной моды HE11, которая существует при любом значении радиуса цилиндрического волновода. Необходимо учитывать, что при малых радиусах волновода вероятность эмиссии в волновую моду очень мала [17][18][19][20][21], и основной вклад в эмиссию вносят утекающие моды.…”