Joel Bleuse
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Joel Bleuse has a total of 236 co-authors. Here are the top co-authors by number of shared publications:
- Jean-Michel Gérard
Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, “Nanophysique et semiconducteurs” Group 1 , 38000 Grenoble
24 shared publications - Niels Gregersen
Technical University of Denmark
17 shared publications - Julien Claudon
Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, “Nanophysique et Semiconducteurs” Group, Grenoble, France
16 shared publications N. Magnea
SP2M/PSC, CEA-Grenoble
8 shared publicationsNitin S. Malik
8 shared publications- Regis Andre
Université Grenoble Alpes
8 shared publications
Latest Publications
- 30 March 2022
- Published by American Physical Society (APS) in Physical Review B
- Vol. 105 (11) , 115308
Unveiling spin-flip processes in a neutral quantum dot using an anisotropic photonic structure
We introduce a method to investigate excitonic spin flips in a neutral quantum dot (QD) that is driven nonresonantly. By inserting the QD in an anisotropic photonic structure, one creates an imbalance between the radiative decay rates of the two bright excitons. Direct spin flips between the bright excitons as well as indirect ones (via a dark exciton) mix the level populations and profoundly affect the degree of linear polarization of the excitonic emission. Measuring this quantity under continuous wave optical excitation yields the spin-flip rate over a broad range of excitation powers. Additional time-resolved experiments allow disentangling the contributions of bright-bright and dark-bright spin flips in the low-excitation regime. After providing theoretical background, we demonstrate the method on a self-assembled InAs QD embedded in a GaAs photonic wire featuring an elliptical cross section. For low-excitation power and at , bright-bright spin flips are much slower than dark-bright spin flips, which, in turn, remain much slower than the radiative decays. Upon increasing the temperature, we observe a superlinear increase in the bright-bright spin-flip rate which completely reverses the rate hierarchy above . Moreover, polarization measurements reveal a dramatic increase in the spin-flip rate with the pumping power. Our findings are relevant to spontaneous emission control by anisotropic photonic structures and to the spectral coherence of QD-based quantum light sources.- 30 March 2022
- Published by American Physical Society (APS) in Physical Review B
- Vol. 105 (11) , 115308
Unveiling spin-flip processes in a neutral quantum dot using an anisotropic photonic structure
We introduce a method to investigate excitonic spin flips in a neutral quantum dot (QD) that is driven nonresonantly. By inserting the QD in an anisotropic photonic structure, one creates an imbalance between the radiative decay rates of the two bright excitons. Direct spin flips between the bright excitons as well as indirect ones (via a dark exciton) mix the level populations and profoundly affect the degree of linear polarization of the excitonic emission. Measuring this quantity under continuous wave optical excitation yields the spin-flip rate over a broad range of excitation powers. Additional time-resolved experiments allow disentangling the contributions of bright-bright and dark-bright spin flips in the low-excitation regime. After providing theoretical background, we demonstrate the method on a self-assembled InAs QD embedded in a GaAs photonic wire featuring an elliptical cross section. For low-excitation power and at , bright-bright spin flips are much slower than dark-bright spin flips, which, in turn, remain much slower than the radiative decays. Upon increasing the temperature, we observe a superlinear increase in the bright-bright spin-flip rate which completely reverses the rate hierarchy above . Moreover, polarization measurements reveal a dramatic increase in the spin-flip rate with the pumping power. Our findings are relevant to spontaneous emission control by anisotropic photonic structures and to the spectral coherence of QD-based quantum light sources.- Open Access
- 19 October 2021
- Published by Springer Nature in Light: Science & Applications
- Vol. 10 (1) , 1-15
Tailoring the properties of quantum dot-micropillars by ultrafast optical injection of free charge carriers
We review recent studies of cavity switching induced by the optical injection of free carriers in micropillar cavities containing quantum dots. Using the quantum dots as a broadband internal light source and a streak camera as detector, we track the resonance frequencies for a large set of modes with picosecond time resolution. We report a record-fast switch-on time constant (1.5 ps) and observe major transient modifications of the modal structure of the micropillar on the 10 ps time scale: mode crossings are induced by a focused symmetric injection of free carriers, while a lifting of several mode degeneracies is observed when off-axis injection breaks the rotational symmetry of the micropillar. We show theoretically and experimentally that cavity switching can be used to tailor the dynamic properties of the coupled QD–cavity system. We report the generation of ultrashort spontaneous emission pulses (as short as 6 ps duration) by a collection of frequency-selected QDs in a switched pillar microcavity. These pulses display a very small coherence length, attractive for ultrafast speckle-free imaging. Moreover, the control of QD-mode coupling on the 10 ps time scale establishes cavity switching as an appealing resource for quantum photonics.
- 19 October 2021
- Published by Springer Nature in Light: Science & Applications
- Vol. 10 (1) , 1-15
Open AccessTailoring the properties of quantum dot-micropillars by ultrafast optical injection of free charge carriers
We review recent studies of cavity switching induced by the optical injection of free carriers in micropillar cavities containing quantum dots. Using the quantum dots as a broadband internal light source and a streak camera as detector, we track the resonance frequencies for a large set of modes with picosecond time resolution. We report a record-fast switch-on time constant (1.5 ps) and observe major transient modifications of the modal structure of the micropillar on the 10 ps time scale: mode crossings are induced by a focused symmetric injection of free carriers, while a lifting of several mode degeneracies is observed when off-axis injection breaks the rotational symmetry of the micropillar. We show theoretically and experimentally that cavity switching can be used to tailor the dynamic properties of the coupled QD–cavity system. We report the generation of ultrashort spontaneous emission pulses (as short as 6 ps duration) by a collection of frequency-selected QDs in a switched pillar microcavity. These pulses display a very small coherence length, attractive for ultrafast speckle-free imaging. Moreover, the control of QD-mode coupling on the 10 ps time scale establishes cavity switching as an appealing resource for quantum photonics.
- 10 May 2021
- Published by AIP Publishing in Applied Physics Letters
- Vol. 118 (19) , 194002
A nanowire optical nanocavity for broadband enhancement of spontaneous emission
To deliver an optimal performance for photonic quantum technologies, semiconductor quantum dots should be integrated in a carefully designed photonic structure. Here, we introduce a nanowire optical nanocavity designed for free-space emission. Thanks to its ultrasmall mode volume, this simple structure offers a large acceleration of spontaneous emission (predicted Purcell factor of 6.3) that is maintained over a 30-nm bandwidth. In addition, a dielectric screening effect strongly suppresses the emission into the 3D continuum of radiation modes. The fraction of spontaneous emission funneled into the cavity mode reaches 0.98 at resonance and exceeds 0.95 over a 100-nm spectral range. Close-to-optimal collection efficiency is maintained over an equivalent bandwidth and reaches a predicted value of 0.54 at resonance for a first lens with a numerical aperture (NA) of 0.75. As a first experimental demonstration of this concept, we fabricate an Au–SiO2–GaAs device embedding isolated InAs quantum dots. We measure a maximal acceleration of spontaneous emission by a factor as large as 5.6 and a bright quantum dot emission (collection efficiency of 0.35 into NA = 0.75). This nanowire cavity constitutes a promising building block to realize advanced sources of quantum light for a broad range of material systems.
- 10 May 2021
- Published by AIP Publishing in Applied Physics Letters
- Vol. 118 (19) , 194002
A nanowire optical nanocavity for broadband enhancement of spontaneous emission
To deliver an optimal performance for photonic quantum technologies, semiconductor quantum dots should be integrated in a carefully designed photonic structure. Here, we introduce a nanowire optical nanocavity designed for free-space emission. Thanks to its ultrasmall mode volume, this simple structure offers a large acceleration of spontaneous emission (predicted Purcell factor of 6.3) that is maintained over a 30-nm bandwidth. In addition, a dielectric screening effect strongly suppresses the emission into the 3D continuum of radiation modes. The fraction of spontaneous emission funneled into the cavity mode reaches 0.98 at resonance and exceeds 0.95 over a 100-nm spectral range. Close-to-optimal collection efficiency is maintained over an equivalent bandwidth and reaches a predicted value of 0.54 at resonance for a first lens with a numerical aperture (NA) of 0.75. As a first experimental demonstration of this concept, we fabricate an Au–SiO2–GaAs device embedding isolated InAs quantum dots. We measure a maximal acceleration of spontaneous emission by a factor as large as 5.6 and a bright quantum dot emission (collection efficiency of 0.35 into NA = 0.75). This nanowire cavity constitutes a promising building block to realize advanced sources of quantum light for a broad range of material systems.
- Open Access
- 1 December 2020
- Published by AIP Publishing in APL Photonics
- Vol. 5 (12) , 126104
Probing microcavity switching events on the picosecond time scale using quantum dots as a broadband internal fluorescent source
We report on ultrafast all-optical switching experiments performed on pillar microcavities containing a collection of quantum dots (QDs). Using QDs as a broadband internal light source and a detection setup based on a streak camera, we track in parallel the frequencies of a large set (>10) of resonant modes of an isolated micropillar during the entire duration of switching events and with a 2 ps temporal resolution. Being much faster and more convenient than standard approaches based on pump–probe spectroscopy, this method is very well suited for in-depth studies of cavity switching, noticeably in view of applications in the field of quantum photonics. We report as a first demonstrative example an investigation of the switch-on time constant τon dependence as a function of the pump power and the observation of a remarkably low value of τon(≈1.5 ps) for optimized pumping conditions. As a second illustration, we report the observation of a transient lifting of the degeneracy of a polarization-degenerate cavity mode, induced by a non-centrosymmetric injection of free carriers.
- 1 December 2020
- Published by AIP Publishing in APL Photonics
- Vol. 5 (12) , 126104
Open AccessProbing microcavity switching events on the picosecond time scale using quantum dots as a broadband internal fluorescent source
We report on ultrafast all-optical switching experiments performed on pillar microcavities containing a collection of quantum dots (QDs). Using QDs as a broadband internal light source and a detection setup based on a streak camera, we track in parallel the frequencies of a large set (>10) of resonant modes of an isolated micropillar during the entire duration of switching events and with a 2 ps temporal resolution. Being much faster and more convenient than standard approaches based on pump–probe spectroscopy, this method is very well suited for in-depth studies of cavity switching, noticeably in view of applications in the field of quantum photonics. We report as a first demonstrative example an investigation of the switch-on time constant τon dependence as a function of the pump power and the observation of a remarkably low value of τon(≈1.5 ps) for optimized pumping conditions. As a second illustration, we report the observation of a transient lifting of the degeneracy of a polarization-degenerate cavity mode, induced by a non-centrosymmetric injection of free carriers.
- 19 November 2020
- Published by American Physical Society (APS) in Physical Review B
- Vol. 102 (19) , 195205
Optical determination of the band gap and band tail of epitaxial at low temperatureWe report on the precise determination, in epitaxial layer, of both the band gap and the characteristic Urbach energy that describes the density of localized, defect states in the gap. Various origins for these defect band tail states have been considered, together with the corresponding modeling for their density of states, in order to fit the whole of the optical spectral data. The interest of the methodology developed here is to account quantitatively not only for the absorption and steady-state photoluminescence data but also for the time-resolved photoluminescence spectra. We compare the different origins of localized band tail states to select the standard textbook, Urbach tail model that corresponds to short-range band gap fluctuations. Such an approach is different from the one most often used to evaluate the energy extent of the localized states, which is the Stokes shift between the energies of the photoluminescence emission and the absorption threshold. The advantage of the present method is that no arbitrary choice of the low power excitation has to be done to select the photoluminescence emission spectrum and its peak energy. Thanks to this systematic study of both photoluminescence excitation and time-resolved photoluminescence spectra at low temperature (6 K), the values meV and meV are found for this promising absorber for thin films photovoltaics.- 19 November 2020
- Published by American Physical Society (APS) in Physical Review B
- Vol. 102 (19) , 195205
Optical determination of the band gap and band tail of epitaxial at low temperatureWe report on the precise determination, in epitaxial layer, of both the band gap and the characteristic Urbach energy that describes the density of localized, defect states in the gap. Various origins for these defect band tail states have been considered, together with the corresponding modeling for their density of states, in order to fit the whole of the optical spectral data. The interest of the methodology developed here is to account quantitatively not only for the absorption and steady-state photoluminescence data but also for the time-resolved photoluminescence spectra. We compare the different origins of localized band tail states to select the standard textbook, Urbach tail model that corresponds to short-range band gap fluctuations. Such an approach is different from the one most often used to evaluate the energy extent of the localized states, which is the Stokes shift between the energies of the photoluminescence emission and the absorption threshold. The advantage of the present method is that no arbitrary choice of the low power excitation has to be done to select the photoluminescence emission spectrum and its peak energy. Thanks to this systematic study of both photoluminescence excitation and time-resolved photoluminescence spectra at low temperature (6 K), the values meV and meV are found for this promising absorber for thin films photovoltaics.- Open Access
Optical Determination of the Band Gap and Band Tail of Epitaxial Ag$_2$ZnSnSe$_4$ at Low Temperature
We report on the precise determination of both the band gap E$_\text{g}$, and the characteristic energy $U$ of the band tail of localized defect states, for monocrystalline Ag$_2$ZnSnSe$_4$. Both photoluminescence excitation and time-resolved photoluminescence studies lead to E$_\text{g} = 1223\pm3$ meV, and $U = 20\pm3$ meV, at 6 K. The interest of the methodology developed here is to account quantitatively for the time-resolved photoluminescence and photoluminescence excitation spectra by only considering standard textbook density of states, and state filling effects. Such an approach is different from the one most often used to evaluate the energy extent of the localized states, namely by measuring the energy shift between the photoluminescence emission and the excitation one -- the so-called Stokes shift. The advantage of the present method is that no arbitrary choice of the low power excitation has to be done to select the photoluminescence emission spectrum and its peak energy.Open AccessOptical Determination of the Band Gap and Band Tail of Epitaxial Ag$_2$ZnSnSe$_4$ at Low Temperature
We report on the precise determination of both the band gap E$_\text{g}$, and the characteristic energy $U$ of the band tail of localized defect states, for monocrystalline Ag$_2$ZnSnSe$_4$. Both photoluminescence excitation and time-resolved photoluminescence studies lead to E$_\text{g} = 1223\pm3$ meV, and $U = 20\pm3$ meV, at 6 K. The interest of the methodology developed here is to account quantitatively for the time-resolved photoluminescence and photoluminescence excitation spectra by only considering standard textbook density of states, and state filling effects. Such an approach is different from the one most often used to evaluate the energy extent of the localized states, namely by measuring the energy shift between the photoluminescence emission and the excitation one -- the so-called Stokes shift. The advantage of the present method is that no arbitrary choice of the low power excitation has to be done to select the photoluminescence emission spectrum and its peak energy. - 14 March 2018
- Published by Springer Nature in Journal of Electronic Materials
- Vol. 47 (8) , 4282-4288
Potential Fluctuations and Localization Effects in CZTS Single Crystals, as Revealed by Optical Spectroscopy
- 14 March 2018
- Published by Springer Nature in Journal of Electronic Materials
- Vol. 47 (8) , 4282-4288
Potential Fluctuations and Localization Effects in CZTS Single Crystals, as Revealed by Optical Spectroscopy
- 1 July 2017
- Published by Institute of Electrical and Electronics Engineers (IEEE)
- p. 119-120
Optical localization of quantum dots in tapered nanowires
In this work we have measured the far-field emission patterns of In As quantum dots embedded in a GaAs tapered nanowire and used an open-geometry Fourier modal method for determining the radial position of the quantum dots by computing the far-field emission pattern for different quantum dot locations.
- 1 July 2017
- Published by Institute of Electrical and Electronics Engineers (IEEE)
- p. 119-120
Optical localization of quantum dots in tapered nanowires
In this work we have measured the far-field emission patterns of In As quantum dots embedded in a GaAs tapered nanowire and used an open-geometry Fourier modal method for determining the radial position of the quantum dots by computing the far-field emission pattern for different quantum dot locations.
- 1 June 2017
- Published by Institute of Electrical and Electronics Engineers (IEEE)
- p. 1
Determination of radial quantum dot position in trumpet nanowires from far field measurements
A quantum dot embedded in a trumpet nanowire has been shown to be a good candidate for realising an efficient on-demand single-photon source. At the lateral quantum dot position the diameter of the nanowire only supports two guided modes - the HE11 and TE01 modes. These modes are excited by the quantum dot after recombination of an electron-hole pair. The slow expansion of the nanowire diameter secures an adiabatic propagation of the modes through the taper meaning that the occupation of the HE11 and TE01 modes will remain the same at the top of the trumpet nanowire (see Fig. 1 right). It is for now not possible to control the radial position of the quantum dot in the nanowires and thus it is important to experimentally determine this after fabrication.
- 1 June 2017
- Published by Institute of Electrical and Electronics Engineers (IEEE)
- p. 1
Determination of radial quantum dot position in trumpet nanowires from far field measurements
A quantum dot embedded in a trumpet nanowire has been shown to be a good candidate for realising an efficient on-demand single-photon source. At the lateral quantum dot position the diameter of the nanowire only supports two guided modes - the HE11 and TE01 modes. These modes are excited by the quantum dot after recombination of an electron-hole pair. The slow expansion of the nanowire diameter secures an adiabatic propagation of the modes through the taper meaning that the occupation of the HE11 and TE01 modes will remain the same at the top of the trumpet nanowire (see Fig. 1 right). It is for now not possible to control the radial position of the quantum dot in the nanowires and thus it is important to experimentally determine this after fabrication.
- 5 October 2015
- Published by AIP Publishing in Applied Physics Letters
- Vol. 107 (14) , 141106
Highly directive and Gaussian far-field emission from “giant” photonic trumpets
Photonic trumpets are broadband dielectric antennas that efficiently funnel the emission of a point-like quantum emitter—such as a semiconductor quantum dot—into a Gaussian free-space beam. After describing guidelines for the taper design, we present a “giant” photonic trumpet. The device features a bottom diameter of 210 nm and a wide top facet. Using Fourier microscopy, we show that 95% of the emitted beam is intercepted by a modest numerical aperture of 0.35. Furthermore, far-field measurements reveal a highly Gaussian angular profile, in agreement with the predicted overlap to a Gaussian beam . Future application prospects include the direct coupling of these devices to a cleaved single-mode optical fiber. The calculated transmission from the taper base to the fiber already reaches 0.59, and we discuss strategies to further improve this figure of merit.- 5 October 2015
- Published by AIP Publishing in Applied Physics Letters
- Vol. 107 (14) , 141106
Highly directive and Gaussian far-field emission from “giant” photonic trumpets
Photonic trumpets are broadband dielectric antennas that efficiently funnel the emission of a point-like quantum emitter—such as a semiconductor quantum dot—into a Gaussian free-space beam. After describing guidelines for the taper design, we present a “giant” photonic trumpet. The device features a bottom diameter of 210 nm and a wide top facet. Using Fourier microscopy, we show that 95% of the emitted beam is intercepted by a modest numerical aperture of 0.35. Furthermore, far-field measurements reveal a highly Gaussian angular profile, in agreement with the predicted overlap to a Gaussian beam . Future application prospects include the direct coupling of these devices to a cleaved single-mode optical fiber. The calculated transmission from the taper base to the fiber already reaches 0.59, and we discuss strategies to further improve this figure of merit.