Quantum dot micropillar cavities with quality factors exceeding 250,000

Schneider, Christian; Gold, Peter Werner; Reitzenstein, Stephan; Höfling, Sven; Kamp, M.

doi:10.1007/s00340-015-6283-x

Cited by 55 publications

(47 citation statements)

References 35 publications

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“…is an explicit function for scattering loss of the micro-pillar of radius R with the Bessel function of the first kind J 0 (k t R), where k t = n 2 k 2 −β 2 , with the core refractive index n, the mode propagation constant β, and the sidewall loss parameter κ. The only free parameter for fitting is κ and the fit estimates κ = 3.8(2) × 10 −10 m, comparable to results by others 42,43 . The expected Purcell factors are in the range of 2 − 3 for the measured Q factors with the mode volume from the electric field distribution from FDTD simulations, see Fig.…”

supporting

confidence: 85%

Filter-free single-photon quantum dot resonance fluorescence in an integrated cavity-waveguide device

Huber¹,

Davanço²,

Müller³

et al. 2020

Optica

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Semiconductor quantum dots embedded in micro-pillar cavities are excellent emitters of single photons when pumped resonantly. Often, the same spatial mode is used to both resonantly excite a quantum dot and to collect the emitted single photons, requiring cross-polarization to reduce the uncoupled scattered laser light. This inherently reduces the source brightness to 50 %. Critically, for some quantum applications the total efficiency from generation to detection must be over 50 %. Here, we demonstrate a resonant-excitation approach to creating single photons that is free of any cross-polarization, and in fact any filtering whatsoever. It potentially increases single-photon rates and collection efficiencies, and simplifies operation. This integrated device allows us to resonantly excite single quantum-dot states in several cavities in the plane of the device using connected waveguides, while the cavity-enhanced single-photon fluorescence is directed vertical (off-chip) in a Gaussian mode. We expect this design to be a prototype for larger chip-scale quantum photonics.In the on-going development of quantum optical technologies, devices will need to be easier to use, more compact, robust, and scalable, making them available to a broader community. These technologies include applications in quantum communication 1-4 , optical quantum metrology 5-8 , and optical quantum computation and simulation 9-12 . For example, a true single photon source on chip as a turnkey device would open quantum technologies to a unprecedented user group.Quantum dot (QD) excitonic states are excellent quantum emitters, showing bright emission of single photons 13-17 and excellent suppression of multi-photons states 16,18,19 . These properties are achieved due to the level structure and radiative efficiency of the optically allowed lowest level exciton states.While single QD exciton emission is inherently bright with low multi-photon contribution, the emitted light can be further enhanced and directed into a Gaussian mode by coupling the QD to an optical cavity. 14,20,21 In the weak coupling regime between emitter and cavity, this is known as the Purcell effect 22 . For a cavity with quality factor Q and mode volume V , the Purcell effect is characterized by F p = 3 4π 2 ( λ n ) 3 Q V for a dipole emitter in resonance with the cavity, placed at the maximum of the electric field, and with proper aligned polarization. λ is the wavelength of fundamental mode resonance and n is the material's index of refraction. With the emitter and cavity in resonance, this shortens the radiative lifetime. While various optical cavities can be used 17 , a particularly useful cavity is the pillar microcavity 23 because the single-photon emission is in a well defined Gaussian mode. Since weak cavity coupling reduces the radiative lifetime, decoherence contributions to the emission linewidth are reduced, leading to bandwidths that can approach the spontaneous-emission lifetime-limit, and near unity photon indistinguishability 17,24 .Because of the single mode n...

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supporting

confidence: 85%

Filter-free single-photon quantum dot resonance fluorescence in an integrated cavity-waveguide device

Huber¹,

Davanço²,

Müller³

et al. 2020

Optica

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“…The width of this resonance defines the socalled quality factor or Q-factor via Q = ω/δω, which is directly linked to the lifetime τ of photons in the cavity Q = ωτ . In (Al)GaAs DBR based microcavities, Q-factors of several 100000 are available [37,38] which reflects the high material qualities available by state-ofthe-art epitaxy.…”

Section: Microcavity Photonsmentioning

confidence: 99%

Exciton-polariton trapping and potential landscape engineering

et al. 2016

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Exciton-polaritons in semiconductor microcavities have become a model system for the studies of dynamical Bose-Einstein condensation, macroscopic coherence, many-body effects, nonclassical states of light and matter, and possibly quantum phase transitions in a solid state. These low-mass bosonic quasiparticles can condense at comparatively high temperatures up to 300 K, and preserve the fundamental properties of the condensate, such as coherence in space and time domain, even when they are out of equilibrium with the environment. Although the presence of a confining potential is not strictly necessary in order to observe Bose-Einstein condensation, engineering of the polariton confinement is a key to controlling, shaping, and directing the flow of polaritons. Prototype polariton-based optoelectronic devices rely on ultrafast photon-like velocities and strong nonlinearities exhibited by polaritons, as well as on their tailored confinement. Nanotechnology provides several pathways to achieving polariton confinement, and the specific features and advantages of different methods are discussed in this review. Being hybrid exciton-photon quasiparticles, polaritons can be trapped via their excitonic as well as photonic component, which leads to a wide choice of highly complementary trapping techniques. Here, we highlight the almost free choice of the confinement strengths and trapping geometries that provide powerful means for control and manipulation of the polariton systems both in the semi-classical and quantum regimes. Furthermore, the possibilities to observe effects of the polariton blockade, Mott insulator physics, and population of higher-order energy bands in sophisticated lattice potentials are discussed. Observation of such effects could lead to realization of novel polaritonic non-classical light sources and quantum simulators.

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“…Micropillar structures achieve optical confinement both parallel to the pillar axis (by in‐phase reflection from the dielectric mirrors) and normal to the pillar axis through total internal reflection due to the large difference in refractive index . The high level of sophistication achievable using inorganic semiconductor processing techniques has allowed micropillar structures to be realized having very high quality (Q) factors, with recent pillar structures demonstrated having Q‐factors in excess of 250 000 . This strong confinement can be used to engineer enhancements in spontaneous emission rates (the Purcell factor), and thus by placing a single quantum emitter in a micropillar, a device can be created that acts as a source of near indistinguishable single photons .…”

Section: Introductionmentioning

confidence: 99%

Optical‐Mode Structure of Micropillar Microcavities Containing a Fluorescent Conjugated Polymer

et al. 2019

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The light emission from a series of micropillar microcavities containing a fluorescent, red‐emitting conjugated polymer, is explored. Cavities are fabricated by defining two dielectric mirrors either side of a polymer active region. Focused ion‐beam (FIB) lithography is then used to etch pillar structures into the planar cavity having diameters between 1 and 11 µm. The photoluminescence (PL) emission of the cavities is characterized using real‐space tomographic and Fourier‐space imaging techniques, with emission shown to be quantized into a mode‐structure resulting from both vertical and lateral optical confinement within the pillar. The optical‐confinement effects which result in a blue‐shift of the fundamental mode as the pillar diameter is reduced is demonstrated, with a model applied to describe the energy and distribution of the confined optical modes.

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Quantum dot micropillar cavities with quality factors exceeding 250,000

Cited by 55 publications

References 35 publications

Filter-free single-photon quantum dot resonance fluorescence in an integrated cavity-waveguide device

Filter-free single-photon quantum dot resonance fluorescence in an integrated cavity-waveguide device

Exciton-polariton trapping and potential landscape engineering

Optical‐Mode Structure of Micropillar Microcavities Containing a Fluorescent Conjugated Polymer

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