Anomalous dip observed in intensity autocorrelation function as an inherent nature of single-photon emitters

We report on the observation of linearly polarized single photon antibunching in the excitonic emission from a site-controlled InGaN quantum dot. The measured second order coherence function exhibits a significant dip at zero time difference, corresponding to g(m)(2) (0) = 0: 90 under continuous laser excitation. This relatively high value of g(m)(2) (0) is well understood by a model as the combination of short exciton life time (320 ps), limited experimental timing resolution and the presence of an uncorrelated broadband background emission from the sample. Our result provides the first rigorous evidence of InGaN quantum dot formation on hexagonal GaN pyramids, and it highlights a great potential in these dots as fast polarized single photon emitters if the background emission can be eliminated.

Funding Agencies|Carl Trygger Foundation for Scientific Research; Swedish Research Council (VR); Nano-N consortium - Swedish Foundation for Strategic Research (SSF); Knut and Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Font-D, at Linkoping University

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confidence: 99%

Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot

Jemsson

Machhadani

Karlsson

et al. 2014

“…We observed clear anti-bunching dip at zero delay of the two optical detection paths and therefore demonstrated single-photon emission. 18,19 With this metallic nanostructure, we also demonstrated the high singlephoton extraction efficiency of $18%. It is well known that photon extraction efficiency from a planar semiconductor surface is limited to less than 2% due to the total internal reflection at the air/semiconductor interface, and therefore this is a drastic improvement.…”

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confidence: 83%

High-Q resonance modes observed in a metallic nanocavity

Takemoto

Ishihara

Kurosawa

et al. 2013

Self Cite

Metallic nanocavities have been actively studied for realizing nanolasers with low threshold. Presence of resonance modes with high cavity Q values is the indication of low internal loss that leads to low threshold lasing. However, cavity Q values observed in metallic nanocavities below lasing threshold remain low at present on the order of 100 to 500. We study the possibility to realize higher resonance Q values with a metallic nanocavity. For probing purpose of cavity modes we propose to employ broad mid-gap-state optical emission of n-type GaAs. With this method we report the observation of a resonance mode with the high Q value of 3800 at room temperature with the metallic nanocavity. The cavity mode is identified as a whispering-gallery mode with finite-element- method simulation

“…The solid curve in red is the least-square fit to the data with the commonly accepted formula. 2,15 The fitting results in g (2) (0) ¼ 0.3, and the antibunching dip below 0.5 is characteristic of a single-photon emitter (SPE). Further suppression of multi-photon emission with g (2) (0) < 0.1 was achieved by quasi-resonant excitation with low excitation power.…”

Section: à2mentioning

confidence: 99%

“…14,15 This structure is completely embedded in metal and is fundamentally flat and mechanically stable. Direct contact of this kind of photon sources to a single-mode fiber will provide a fiberbased photon source with long-term stability.…”

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confidence: 99%

“…Therefore, titanium (Ti) and/or niobium (Nb) hard metals were selected for the embedding metals in these samples. 15,17 However, optical reflectivity of these hard metals is generally low, and it is a drawback for efficient photon extraction. Silver (Ag) is known to have high optical reflectivity in the near-infrared spectral region although the Vickers hardness of Ag is $1/4 and $1/5 of that of Ti and Nb, respectively.…”

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confidence: 99%

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Bright single-photon source based on an InAs quantum dot in a silver-embedded nanocone structure

Liu

Asano

Odashima

et al. 2013

Self Cite

High photon-extraction efficiency is strongly required for a practical single-photon source. We succeed in fabricating metal (sliver)-embedded nanocone structure incorporating an InAs quantum dot. Efficient photon emission of $200 000 photons per second is detected and single-photon emission is demonstrated using autocorrelation measurements. The photon-extraction efficiency as high as 24.6% is obtained from the structure. V C 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4801334]Within the past decade, much attention has been devoted to the development of single-photon sources for future applications in quantum information processing and quantum communications based on a wide variety of systems, such as single atoms, molecules, and color centers in diamonds. [1][2][3] Among these systems, single quantum dots (QDs) are potential candidates owing to their discrete levels, which offer high emission rates, narrow spectral line widths, and wide tunability of emission wavelengths.4-9 Significant progress has been made to achieve efficient single-photon sources. One of the key issues is to enhance photon-extraction efficiency, which is defined as the collection efficiency of photons emitted from a QD into the first lens in an experimental optical setup. Efficient single-photon emission has been demonstrated from single QDs in distributed Bragg reflector (DBR) microcavities with pillar structures 4,5 and inner lateral confinement, 6 photonic nanowires, 7,8 trumpet structures, 9 horn structures, 10 and so on. Coupling of photon emission from QDs to metallic nanoantennas, 11 confined plasmon modes, 12 as well as photonic waveguides 13 was also proposed. Although photonic nanowires and microcavity pillars exhibited high photon-extraction efficiencies, mechanical stability related to their high aspect ratio and their stability to couple to outer photon collection optics remain as challenging issues.Recently, we have introduced a metal-embedded GaAs pillar structure containing single InAs QDs.14,15 This structure is completely embedded in metal and is fundamentally flat and mechanically stable. Direct contact of this kind of photon sources to a single-mode fiber will provide a fiberbased photon source with long-term stability. 16 With this metal-embedded pillar structure, we have observed the photon-extraction efficiency of $8% (efficiency collected by the first lens with the numerical aperture (NA) of 0.42).14 In this case, GaAs substrates were removed by mechanical cleavage during the metal-embedding process, and hard metals were necessary for the sample preparation. Therefore, titanium (Ti) and/or niobium (Nb) hard metals were selected for the embedding metals in these samples. 15,17 However, optical reflectivity of these hard metals is generally low, and it is a drawback for efficient photon extraction. Silver (Ag) is known to have high optical reflectivity in the near-infrared spectral region although the Vickers hardness of Ag is $1/4 and $1/5 of that of Ti and Nb, respectively. In this paper, we report on the...