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Subject: search.filters.subject.530Subject: search.filters.subject.620Start date: 2020Author: search.filters.author.Michler, PeterAuthor: search.filters.author.Portalupi, Simone Luca

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Now showing 1 - 4 of 4
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    ItemOpen Access
    Integrated optoelectronic devices using lab‐on‐fiber technology
    (2022) Ricciardi, Armando; Zimmer, Michael; Witz, Norbert; Micco, Alberto; Piccirillo, Federica; Giaquinto, Martino; Kaschel, Mathias; Burghartz, Joachim; Jetter, Michael; Michler, Peter; Cusano, Andrea; Portalupi, Simone Luca
    Silica fibers are nowadays cornerstones in several technological implementations from long‐distance communication, to sensing applications in many scenarios. To further enlarge the functionalities, the compactness, and the performances of fiber‐based devices, one needs to reliably integrate small‐footprint components such as sensors, light sources, and detectors onto single optical fiber substrates. Here, a novel proof of concept is presented to deterministically integrate optoelectronic chips onto the facet of an optical fiber, further implementing the electrical contacting between the chip and fiber itself. The CMOS‐compatible procedure is based on a suitable combination of metal deposition, laser machining, and micromanipulation, directly applied onto the fiber tip. The proposed method is validated by transferring, aligning, and bonding a quantum‐well based laser on the core of a multimode optical fiber. The successful monolithic device integration on fiber shows simultaneously electrical contacting between the laser and the ferrule, and 20% light in‐coupling in the fiber. These results pave new ways to develop the next generation of optoelectronic systems on fiber. The technological approach will set a new relevant milestone along the lab‐on‐fiber roadmap, opening new avenues for a novel class of integrated optoelectronic fiber platforms, featuring unrivaled miniaturization, compactness, and performances levels, designed for specific applications.
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    ItemOpen Access
    High-rate intercity quantum key distribution with a semiconductor single-photon source
    (2024) Yang, Jingzhong; Jiang, Zenghui; Benthin, Frederik; Hanel, Joscha; Fandrich, Tom; Joos, Raphael; Bauer, Stephanie; Kolatschek, Sascha; Hreibi, Ali; Rugeramigabo, Eddy Patrick; Jetter, Michael; Portalupi, Simone Luca; Zopf, Michael; Michler, Peter; Kück, Stefan; Ding, Fei
    Quantum key distribution (QKD) enables the transmission of information that is secure against general attacks by eavesdroppers. The use of on-demand quantum light sources in QKD protocols is expected to help improve security and maximum tolerable loss. Semiconductor quantum dots (QDs) are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution. Here we report on the first intercity QKD experiment using a bright deterministic single photon source. A BB84 protocol based on polarisation encoding is realised using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure. Utilising the 79 km long link with 25.49 dB loss (equivalent to 130 km for the direct-connected optical fibre) between the German cities of Hannover and Braunschweig, a record-high secret key bits per pulse of 4.8 × 10 -5 with an average quantum bit error ratio of ~ 0.65% are demonstrated. An asymptotic maximum tolerable loss of 28.11 dB is found, corresponding to a length of 144 km of standard telecommunication fibre. Deterministic semiconductor sources therefore challenge state-of-the-art QKD protocols and have the potential to excel in measurement device independent protocols and quantum repeater applications.
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    Optical charge injection and coherent control of a quantum-dot spin-qubit emitting at telecom wavelengths
    (2022) Dusanowski, Łukasz; Nawrath, Cornelius; Portalupi, Simone Luca; Jetter, Michael; Huber, Tobias; Klembt, Sebastian; Michler, Peter; Höfling, Sven
    Solid-state quantum emitters with manipulable spin-qubits are promising platforms for quantum communication applications. Although such light-matter interfaces could be realized in many systems only a few allow for light emission in the telecom bands necessary for long-distance quantum networks. Here, we propose and implement an optically active solid-state spin-qubit based on a hole confined in a single InAs/GaAs quantum dot grown on an InGaAs metamorphic buffer layer emitting photons in the C-band. We lift the hole spin-degeneracy using an external magnetic field and demonstrate hole injection, initialization, read-out and complete coherent control using picosecond optical pulses. These results showcase a solid-state spin-qubit platform compatible with preexisting optical fiber networks.
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    ItemOpen Access
    Collecting telecom photons from circular Bragg gratings using optical fibers and 3D printed micro‐lenses
    (2025) Tran, Nam; Ruchka, Pavel; Jakovljevic, Sara; Breiholz, Benjamin; Gierß, Peter; Vijayan, Ponraj; Jimenez, Carlos Eduardo; Herkommer, Alois; Jetter, Michael; Portalupi, Simone Luca; Giessen, Harald; Michler, Peter
    Deterministic sources of quantum light are becoming increasingly relevant in the development of quantum communication, particularly in deployed fiber networks. Therefore, efficient fiber‐coupled sources at telecom wavelength are highly sought after. With this goal in mind, the fiber coupling performance of quantum dots is systematically investigated in optical resonators under three experimental configurations. For the first time coupling efficiency and sensitivity are quantified to spatial displacement for single‐mode fibers with 3D printed optics on their tip, and benchmark their behavior over a commercial cleaved‐cut fiber and a standard optical setup. The reduction of the required optical elements when operating with a lensed or a bare fiber allows for an increased end‐to‐end efficiency over a standard setup. For the perspective of realizing a mechanically stable fiber‐coupled source, the spatial tolerance is precisely quantified to fiber‐cavity misalignment, observing less than 50%$50 \,\%$count rate drop for several micrometers displacement. In the spirit of precise quantification and reproducibility, the experiments are performed on multiple photonic resonators. These results will play a key role in the future development of fiber‐coupled sources of quantum light.