Single-photon sources are key building blocks in most of the emerging secure telecommunication and quantum information processing schemes. Semiconductor quantum dots (QD) have been proven to be the ...most prospective candidates. However, their practical use in fiber-based quantum communication depends heavily on the possibility of operation in the telecom bands and at temperatures not requiring extensive cryogenic systems. In this paper we present a temperature-dependent study on single QD emission and single-photon emission from metalorganic vapour-phase epitaxy-grown InGaAs/GaAs QDs emitting in the telecom O-band at 1.3 μm. Micro-photoluminescence studies reveal that trapped holes in the vicinity of a QD act as reservoir of carriers that can be exploited to enhance photoluminescence from trion states observed at elevated temperatures up to at least 80 K. The luminescence quenching is mainly related to the promotion of holes to higher states in the valence band and this aspect must be primarily addressed in order to further increase the thermal stability of emission. Photon autocorrelation measurements yield single-photon emission with a purity of Formula: see text up to 50 K. Our results imply that these nanostructures are very promising candidates for single-photon sources at elevated (e.g., Stirling cryocooler compatible) temperatures in the telecom O-band and highlight means for improvements in their performance.
We present a numerical method for the accurate and efficient simulation of strongly localized light sources, such as quantum dots, embedded in dielectric micro-optical structures. We apply the method ...in order to optimize the photon extraction efficiency of a single-photon emitter consisting of a quantum dot embedded into a multi-layer stack with further lateral structures. Furthermore, we present methods to study the robustness of the extraction efficiency with respect to fabrication errors and defects.
In this work, we determine the temperature dependence of refractive indices of In
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Al
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Ga
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As and Al
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Ga
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As semiconductor alloys at telecommunication wavelengths in the range from ...room temperature down to 10 K. For that, we measure the temperature-dependent reflectance of two structures: with an Al
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Ga
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As/GaAs distributed Bragg reflector (DBR) designed for 1.3 µm and with an In
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Al
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Ga
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As/InP DBR designed for 1.55 µm. The obtained experimental results are compared to DBR reflectivity spectra calculated within the transfer matrix method to determine refractive index values. We further show that changes due to the thermal expansion of the DBR layers are negligible for our method.
A user‐friendly, fiber‐coupled, single‐photon source operating at telecom wavelengths is a key component of photonic quantum networks providing long‐haul, ultra‐secure data exchange. To take full ...advantage of quantum‐mechanical data protection and to maximize the transmission rate and distance, a true quantum source providing single photons on demand is highly desirable. This great challenge is tackled by developing a ready‐to‐use semiconductor quantum‐dot‐based device that launches single photons at a wavelength of 1.3 µm directly into a single‐mode optical fiber. In the proposed approach, the quantum dot is deterministically integrated into a nanophotonic structure to ensure efficient on‐chip coupling into a fiber. The whole arrangement is integrated into a 19ʺ compatible housing to enable stand‐alone operation by cooling via a compact Stirling cryocooler. The realized source delivers single photons with a multiphoton events probability as low as 0.15 and a single‐photon emission rate of up to 73 kHz into a standard telecom single‐mode fiber.
A user‐friendly, compact, and portable triggered single‐photon source operating in the telecom O‐band is demonstrated. The device provides single photons with g(2)(0) = 0.15 and a flux of up to 73 kHz at a standard physical‐contact single‐mode fiber connector output. A fully deterministic fabrication technology makes it the first application‐ready quantum‐dot‐based source to enable ultra‐secure data exchange in future fiber‐based quantum communication networks.
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