Metal-coated semiconductor nanostructures and simulation of photon extraction and coupling to optical fibers for a solid-state single-photon source

Suemune, I.; Nakajima, Hirochika; Liu, Xiangming; Odashima, Satoru; Asano, Taku; Iijima, H.; Huh, Jae-Hoon; Idutsu, Y.; Sasakura, H.; Kumano, H.

doi:10.1088/0957-4484/24/45/455205

Cited by 15 publications

(13 citation statements)

References 55 publications

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“…In this regard, minimization of the metal absorption loss and efficient collection of photons emitted from the cavities satisfy this request. We have previously observed high external collection efficiency of ~18% photons generated from a quantum dot embedded in a similar metallic pillar structure [33], and the higher efficiencies are predicted by optimizing the structure [34].…”

Section: Resultsmentioning

confidence: 98%

Subwavelength metallic cavities with high-Qresonance modes

Ishihara¹,

Kurosawa²,

Takemoto³

et al. 2015

Nanotechnology

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Metallic cavities have been extensively studied to realize small-volume nanocavities and nanolasers. However cavity-resonance quality (Q) factors of nanolasers observed up to now remain low (up to ~500) due to metal optical absorption. In this paper, we report the observation of highest Q factors of 9000 at low temperature and ~6000 near room temperature in a metallic cavity with a probe of sub-bandgap emission of Si-doped GaAs. We analyze the temperature dependence of cavity-mode resonance wavelengths and show that the refractive-index term dominates the measured temperature dependence. We also show that this refractive-index term is cavity-mode dependent and the fitting procedure offers a new method to identify cavity modes. We simulate the metallic cavity with finite-element method and attribute the high-Q cavity mode to a whispering gallery optical mode. This mode is shown to have isotropic polarization dependence of the output emission, which is preferable for quantum information applications.2

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Section: Resultsmentioning

confidence: 98%

Subwavelength metallic cavities with high-Qresonance modes

Ishihara¹,

Kurosawa²,

Takemoto³

et al. 2015

Nanotechnology

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“…Because InP has a high refractive index of ∼3.5, the total internal reflection at an InP/air interface limits the photon extraction efficiency to below 2% [38]. To prevent this, Nbbased metal-embedded semiconductor pillar structures were fabricated [39].…”

Section: ×10mentioning

confidence: 99%

“…To prevent this, Nbbased metal-embedded semiconductor pillar structures were fabricated [39]. The details of the fabrication process is given elsewhere [38], but the main processes are as follows: First, pillar arrays were fabricated on the sample surface shown in Fig. 1(a) with electron-beam lithography and the subsequent reactive ion etching (RIE).…”

Section: ×10mentioning

confidence: 99%

Optical observation of superconducting density of states in luminescence spectra of InAs quantum dots

et al. 2015

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We study luminescence spectra observed from InAs quantum dots (QDs) embedded in an n-type InGaAs-based heterostructure, where electron Cooper pairs penetrate from an adjacent niobium (Nb) superconductor with the proximity effect. Below the superconducting (SC) critical temperature of Nb, we observe substantial luminescence intensity enhancement and a sharp edge in luminescence spectra of InAs QDs. We explain the observed sharp edge in the luminescence spectra with the proximity effect, that is, with the consideration of opening of SC gap and modification of density of states (DOS) near the electron Fermi level in the n-type semiconductor heterostructure. We demonstrate that the sharp edge luminescence spectra are well reproduced by the SC DOS, with quasiparticle lifetime broadening and a Gaussian distribution of lowest QD state emission lines. We discuss the reason why it has been difficult to observe the sharp edge luminescence spectra in the previous quantum well-based SC light emitting diodes.

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“…7) In the case of an InAs QD embedded in GaAs, the difference of the refractive indices is ∆n ≈ 2.4 and θ CR is 17.1 • . This gives η extract = 0.022, and 97.8% of photons emitted from an InAs QD are lost via the total internal reflection at the interface.…”

mentioning

confidence: 99%

Stable and efficient collection of single photons emitted from a semiconductor quantum dot into a single-mode optical fiber

Kumano

Harada

Suemune

et al. 2016

Appl. Phys. Express

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We study stable and efficient coupling of single photons generated from a quantum dot (QD) into a single-mode fiber (SMF) prepared in a fiber couple module (FCM). We propose a method to focus the objective lens to a sample surface without imaging with the help of laser reflection. By assembling all the constituents, i.e., a pair of lenses, the SMF, and the optical alignment to the QD source, we demonstrate stable single-photon count rate and a high collection efficiency of 43.5 % of the photons emitted in air from the QD into the collection lens in the FCM.The Internet of Things (IoT) 1) has been rapidly progressing recently, and everything will be involved in the network in near future. In such a society, secure and trustable communication is getting increasingly important, and cryptography works as a fundamental platform to provide a privacy preserving authentication and confidentiality to legitimate users. However the present cryptography relies on the computational difficulty, and we cannot completely eliminate the latent risk of the system being disabled by some emerging technologies. Quantum key distribution (QKD) 2) is expected to be a method to cope with such situations, since it can offer absolute security that cannot be breached, even with high-performance computers or algorithms. When information is encoded on single photons, the security is assured quantum mechanically on the condition that ideal single photon sources (SPSs) and detectors can be employed. Implementation of solid-state SPSs is one of the limited choices to realize deterministic SPSs and for future large-scale system integration, with the probability of generating higher number of photons at a time being nearly zero.From this perspective, semiconductor quantum dots (QDs) have been intensively studied and the SPSs 3, 4) working in O-band 5) and C-band 6) have been demonstrated. However, for a QD embedded in a bulk semiconductor, a large difference of the refractive indices at the semiconductor-air interface tends to prevent photon extraction to the air-side. When the critical angle for total internal reflection is θ CR , the photon extraction efficiency is given by *

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Metal-coated semiconductor nanostructures and simulation of photon extraction and coupling to optical fibers for a solid-state single-photon source

Cited by 15 publications

References 55 publications

Subwavelength metallic cavities with high-Qresonance modes

Subwavelength metallic cavities with high-Qresonance modes

Optical observation of superconducting density of states in luminescence spectra of InAs quantum dots

Stable and efficient collection of single photons emitted from a semiconductor quantum dot into a single-mode optical fiber

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