Abstrakti
Semiconductor quantum dots (QDs) have been extensively researched and have attracted a lot of attention for their ability to deterministically generate single and entangled photons. Such solid-state non-classical light sources are implemented, for example, in quantum key distribution protocols and in on-chip linear optical quantum computing. One of the key practical requirements from these sources is for them to emit at a high repetition rate and a common solution is to embed the QDs in a photonic cavity that enhances the spontaneous emission rate of quantum emitters via the Purcell effect Fp~Q/V, where Q is the cavity quality factor and V the mode volume. Typically, moderate/high-Q cavities are being used for enabling Purcell enhancement of the QD emission. [1-3] In our work, we present an alternative approach based on embedding an InAs QD in a hybrid Ag-GaAs nanopillar cavity [Fig. 1(a)]. Such cavities exhibit relatively low Q-factors (20-200), corresponding to a broad
cavity mode linewidth that matches the QD size dispersion, thus rendering the need for tuning obsolete. The nanopillars are approximately 100 nm in diameter and 200 nm in height. The nanoscale dimensions and strong mode confinement result in an ultra-low mode volume ~0.001λ3 and ensures excellent spatial coupling of the QD emission with the cavity mode [Fig. 1(a)]. Consequently, Fp of ~60 is achievable [Fig. 1(b)]. We experimentally realize our structures by fabricating the nanopillars (containing QDs) using e-beam lithography, dry etching and e-beam metal evaporation. The Ag-coated nanopillars are then transferred to another host substrate using a novel template-stripping based approach. The optical investigations of the QD-cavity devices show diameter-dependent intensity statistics peaking at the 100-105 nm cavity diameter range where we expect the cavity resonance to match with QD emission [Fig. 1(d)]. In power-dependent measurements with quasi-resonant excitation we observe an
anomalous behaviour with unchanged spectral features over a broad range of powers. Furthermore, in time-resolved investigation we observe consistently emission trances below the timing resolution of a SPAD-based setup, which already proofs that Fp>10 is achieved. Higher-resolution measurements with a streak camera and photon-correlation with superconducting detectors are soon the started, but these initial results already show the ultrafast nature of the spontaneous emission provided by an InAs QD embedded in a Ag-GaAs nanocavity.
cavity mode linewidth that matches the QD size dispersion, thus rendering the need for tuning obsolete. The nanopillars are approximately 100 nm in diameter and 200 nm in height. The nanoscale dimensions and strong mode confinement result in an ultra-low mode volume ~0.001λ3 and ensures excellent spatial coupling of the QD emission with the cavity mode [Fig. 1(a)]. Consequently, Fp of ~60 is achievable [Fig. 1(b)]. We experimentally realize our structures by fabricating the nanopillars (containing QDs) using e-beam lithography, dry etching and e-beam metal evaporation. The Ag-coated nanopillars are then transferred to another host substrate using a novel template-stripping based approach. The optical investigations of the QD-cavity devices show diameter-dependent intensity statistics peaking at the 100-105 nm cavity diameter range where we expect the cavity resonance to match with QD emission [Fig. 1(d)]. In power-dependent measurements with quasi-resonant excitation we observe an
anomalous behaviour with unchanged spectral features over a broad range of powers. Furthermore, in time-resolved investigation we observe consistently emission trances below the timing resolution of a SPAD-based setup, which already proofs that Fp>10 is achieved. Higher-resolution measurements with a streak camera and photon-correlation with superconducting detectors are soon the started, but these initial results already show the ultrafast nature of the spontaneous emission provided by an InAs QD embedded in a Ag-GaAs nanocavity.
Alkuperäiskieli | Englanti |
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Otsikko | 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) |
Kustantaja | IEEE |
ISBN (elektroninen) | 979-8-3503-4599-5 |
DOI - pysyväislinkit | |
Tila | Julkaistu - 2023 |
OKM-julkaisutyyppi | A4 Artikkeli konferenssijulkaisussa |
Tapahtuma | Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference - Munich, Saksa Kesto: 26 kesäk. 2023 → 30 kesäk. 2023 |
Julkaisusarja
Nimi | Conference on lasers & electro-optics Europe & international quantum electronics conference |
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Kustantaja | IEEE |
ISSN (painettu) | 2639-5452 |
ISSN (elektroninen) | 2833-1052 |
Conference
Conference | Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference |
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Lyhennettä | CLEO/Europe-EQEC |
Maa/Alue | Saksa |
Kaupunki | Munich |
Ajanjakso | 26/06/23 → 30/06/23 |
Julkaisufoorumi-taso
- Jufo-taso 1