Zuniga Jesus - Academia.edu (original) (raw)

Papers by Zuniga Jesus

Applied Physics Letters, Nov 11, 2019

Science, Sep 3, 2021

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

HAL (Le Centre pour la Communication Scientifique Directe), Jul 9, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Jul 25, 2016

The spatial dynamics of the formation of a polariton condensate under a tightly focused excitatio... more The spatial dynamics of the formation of a polariton condensate under a tightly focused excitation is imaged through 2D near-field and far-field 2D tomography in a ZnO microcavity, up to room temperature. The modelling exhibits the role of the outwards polariton flux caused by the reservoir repulsion, that leads to a 3 to 10 fold increase of the condensation threshold and is imprinted in the shape of the polariton condensate.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 25, 2018

Physical review, Feb 11, 2019

Journal of Crystal Growth, Feb 1, 2023

Crystal Growth & Design, Aug 4, 2022

Journal of Applied Physics, Aug 11, 2021

Journal of Applied Physics, Mar 4, 2021

Nanophotonics, Feb 20, 2023

Physical review applied, Nov 23, 2020

ZnO est un materiau semiconducteur presentant des excitons forts, en terme de force d’oscillateur... more ZnO est un materiau semiconducteur presentant des excitons forts, en terme de force d’oscillateur et d’energie de liaison. Il est donc particulierement interessant pour la generation et le controle de condensats de polaritons, jusqu’a temperature ambiante. La realisation de microcavites ZnO planaires de grand facteur de qualite a longtemps constitue un defi important. Nous avons realise des 2011 le premier laser a polaritons ZnO (a T=120K et un desaccord exciton-photon nul) [1], dans une microcavite hybride (DBR AlN/AlGaN, ZnO realise par epitaxie MBE, DBR SiO2/SiN). Son facteur de qualite, Q=450, etait cependant trop faible pour permettre un fonctionnement du laser a polaritons a temperature ambiante. Dans une approche radicalement differente, une microcavite a ensuite ete realisee en inserant une couche active ZnO massive de grande qualite cristalline entre deux miroirs dielectriques SiO2/HfO2 ; le facteur de qualite a alors atteint Q>2000, pour un dedoublement de Rabi de 250 m...

Exciton-photon coupling in a waveguide geometry is attracting more and more interest in the field... more Exciton-photon coupling in a waveguide geometry is attracting more and more interest in the field of polaritonics. Waveguide polaritons are obtained when the exciton and the guided mode of a photonic waveguide are brought in the strong coupling regime, in strong analogy with cavity polaritons in Fabry-Perot resonators. One of the first demonstrations of waveguide polaritons was reported in a waveguide embedding InGaAs/GaAs quantum wells, with a Rabi splitting of 6 meV [Walker et al., APL 102, 012109 (2013) and Nat. Comm. 6, 8317 (2015)], leading to the observation of ultra-low power temporal solitons at T=10K. Nitride materials offer the possibility to investigate polariton physics up to room temperature thanks to the large binding energy and large oscillator strength of the excitons in GaN. The first demonstration of strong coupling in nitrides waveguides was based on InGaN multiple quantum wells, with a Rabi splitting of 63 meV at 4K, and a strong coupling observed up to T=100K [C...

2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 2021

The physics of gain in interband semiconductor lasers is mostly discussed in terms of population ... more The physics of gain in interband semiconductor lasers is mostly discussed in terms of population inversion for electrons and holes and the associated Bernard-Durrafourg condition. Due to the reciprocity between the processes of absorption and stimulated emission, one consequence is that lasing action can only be reached in standard ridge lasers if the pumped section of a laser is longer than the unpumped (absorptive) section. Here we present how a polariton laser, in a ridge waveguide laser geometry very similar to that of standard ridge lasers, operates on a fundamentally different lasing scheme. Alike multi-section lasers, this laser can be optically pumped over an adjustable length, and we show that lasing action is observed for a pumped length equal to only 15% of the cavity. Based on this striking feature, the comparison between polariton gain and population inversion will be didactically discussed.

ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscil... more ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscillator strength and a large exciton binding energy. It therefore raises a strong interest for the generation and control of polariton condensates up to room temperature. The realization of planar ZnO microcavities with good quality factors has long been a strong challenge. We first demonstrated in 2011 a ZnO polariton laser operating at zero exciton-photon detuning and a temperature of 120 K [1], based on a hybrid microcavity (AlN/AlGaN DBR, MBE-grown ZnO, SiO2/SiN DBR) with a quality factor Q=450. This value was still too small to allow the observation of polariton lasing up to room temperature. A different approach was implemented based on a ZnO active layer of high crystalline quality, embedded between two dielectric DBR; such a fully-hybrid microcavity exhibits a high quality factor (Q>2000) and a large Rabi splitting (250 meV). We have observed the condensation of polaritons in this bulk ZnO microcavity over an unprecedented range of exciton-photon compositions and of temperatures, up to room temperature [2]. The complete phase diagram of the ZnO polariton laser has been measured, showing that its threshold is only 6 times larger at 300 K than at 8 K. It is in a good qualitative agreement with the simulations of exciton and polariton relaxation in a kinetic model. This tunability represents an important progress compared to our previous demonstration [1], as well as to other recent reports [3]. It also confers a strong advantage to ZnO microcavities compared to GaN [4], since strong excitonic condensates can here be investigated. The cavity with Q>2000 however presents a strong gradient of the cavity thickness hindering the generation of extended condensates. Equivalent cavities without such a gradient have therefore been developed in the last years, based on high quality AlN/AlGaN DBRs on mesas. Our most recent investigations are dedicated to the role of the shape of the exciting laser spot on the condensate generation. Condensate propagation is observed under tightly focused excitation, driven by the interaction with the reservoir as in GaAs microcavities, whereas localization of the polariton condensates is observed for larger excitation areas.

Spatial observation and optical manipulation of polariton quantum liquids are raising a large int... more Spatial observation and optical manipulation of polariton quantum liquids are raising a large interest in the studies of polariton condensates in microcavities [1]. In this work, we report the study of polariton condensates in a semi-hybrid ZnO microcavity where the condensation of polaritons up to room temperature has been achieved. This cavity is based on high quality AlN/AlGaN DBRs on 200µm ∗ 200µm mesas. The obtention of a low condensation threshold in a microcavity is related to its local quality factor Q. However the generation of the condensate also strongly depends on the photonic disorder of the cavity i.e. on polariton localization. The purpose of this work is to demonstrate the influence of this last parameter using different large excitation shapes. Figure 1.a shows a cross sectional energy mapping below threshold of polaritons at negative detuning. It is done by scanning the sample with a focused CW excitation spot. The energy fluctuation is less than 4 meV and the local quality factor is above 1900. We then excite the sample with large excitation areas. The photoluminescence profile created by an elongated excitation (60µm ∗ 5µm) is shown on figure 1.b. The intensity profile indicates that the polariton condensate is not uniform. In fact we can clearly see the localization of polaritons on sites that can be separated by more than 10 µm . We assume that this effect is related to the photonic disorder. The impact of size and shape of the excitation area on the condensate intensity profile will be discussed.

Semiconductor-based microcavities appear as a prolific system for studying light-matter interacti... more Semiconductor-based microcavities appear as a prolific system for studying light-matter interaction between a spatially-confined photonic mode and an excitonic resonance. The quasiparticles arising from this coupling (microcavity-polaritons) have enabled in the last years the observation of new lasing regimes as well as polariton Bose-Einstein condensates, vortices and lately solitons. In this panorama ZnO appears as an alternative material to more mature ones, such as GaAs or CdTe, with larger oscillator strengths and enhanced exciton stability. These two properties render ZnO very interesting for studies and applications where large particle densities and/or high temperatures are required. However, the fabrication of ZnO-based microcavities is still challenging and it often requires the use of either nitrides or dielectric materials for the DBRs. Indeed, polariton lasing was demonstrated for the first time in a ZnO-based microcavity only in 2011 [1]. In this work we report on the optical study of a fully-hybrid ZnO-based microcavity in which we combine a high quality active region made up of bulk ZnO and a high cavity quality factor, thanks to the use of two dielectric DBRs. With the cavity Q-factor measured to be more than 1500, polariton lasing is clearly observed from low to room temperature, characterized by a strong linewidth reduction, a small blueshift compared to the Rabi splitting, and an increased emission intensity (three orders of magnitude increase). Furthermore, the wedged-shape of the ZnO active region allows accessing a large range of detunings between the exciton and cavity modes. Under these conditions, the polariton lasing regime has been systematically studied as a function of temperature and detuning, from low to room-temperature. The detailed phase diagram demonstrates the important role played by LO-phonons in the dynamics of the polariton relaxation in ZnO [2], evidenced by a local threshold minimum as a function of detuning. The different relaxation regimes, i.e. kinetic Vs thermodynamic, are further investigated by analyzing a thick cavity region where several lower polartion branches (LPBs), with very different excitonic/photonic fractions are observed. Condensation is observed to take place on the optimum branch as determined by the actual detuning and excitation power. These observations are promising for realizing future multi-mode tunable lasers and room temperature optical switches. References [1] T. Guillet et al., Polariton lasing in a hybrid bulk ZnO microcavity, Appl. Phys. Lett. 99 161104, 2011. [2] L. Orosz et al., LO-phonon-assited polariton lasing in a ZnO-based microcaivty, Phys. Rev. B, 85, 121201(R), 2012.

ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscil... more ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscillator strength and a large exciton binding energy. It therefore raises a strong interest for the generation and control of polariton condensates up to room temperature. We have recently reported the condensation of polaritons in a bulk ZnO microcavity over an unprecedented range of exciton-photon compositions and of temperatures, up to room temperature [1]. The complete phase diagram of the ZnO polariton laser has been measured (cf figure 1a), showing that its threshold is only 6 times larger at 300 K than at 8 K. It is in a good qualitative agreement with the simulations of exciton and polariton relaxation in a kinetic model (figure 1b). Strongly excitonic (96% exciton fraction) as well as strongly photonic condensates (83% photon fraction) are realized (figure 1c). Moreover imaging of the condensate allows to evidence in-plane free propagation of the polariton condensate starting from the excitation spot. This tunability is obtained on a fully-hybrid microcavity with a high quality factor (Q>2000) and a large Rabi splitting (250 meV); it represents an important progress compared to our previous demonstration of a ZnO polariton laser in a Q=450 microcavity [2], as well as to other recent reports [3]. It also confers a strong advantage to ZnO microcavities compared to GaN [4], since strong excitonic condensates can here be investigated. Figure 1. (a) Detuning dependence of the polariton condensation threshold for a 2.5 polariton branch, under quasi-continuous excitation; (b) Polariton density at the condensation threshold deduced from the kinetic model; (c) Angle-resolved emission below and above threshold (T=300K, almost zero detuning). The authors acknowledge financial support from FP7 program through ITN networks CLERMONT4 (235114) and SPIN-OPTRONICS (237252). References [1] F. Li et al., Phys. Rev. Lett. 110, 196406 (2013) [2] T. Guillet et al., Appl. Phys. Lett. 98, 211105 (2011) [3] H. Franke et al., New J. Phys. 14, 013037 (2012); T.C. Lu et al., Optics Express 20, 5530 (2012) [4] J. Levrat et al., Phys. Rev. B 81, 125305 (2010)

Applied Physics Letters, Nov 11, 2019

Science, Sep 3, 2021

HAL (Le Centre pour la Communication Scientifique Directe), Jul 9, 2017

HAL (Le Centre pour la Communication Scientifique Directe), Jul 25, 2016

HAL (Le Centre pour la Communication Scientifique Directe), Mar 25, 2018

Physical review, Feb 11, 2019

Journal of Crystal Growth, Feb 1, 2023

Crystal Growth & Design, Aug 4, 2022

Journal of Applied Physics, Aug 11, 2021

Journal of Applied Physics, Mar 4, 2021

Nanophotonics, Feb 20, 2023

Physical review applied, Nov 23, 2020

2021 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), 2021

ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscil... more ZnO is a wide bandgap semiconductor with strong excitonic properties, in particular a large oscillator strength and a large exciton binding energy. It therefore raises a strong interest for the generation and control of polariton condensates up to room temperature. We have recently reported the condensation of polaritons in a bulk ZnO microcavity over an unprecedented range of exciton-photon compositions and of temperatures, up to room temperature [1]. The complete phase diagram of the ZnO polariton laser has been measured (cf figure 1a), showing that its threshold is only 6 times larger at 300 K than at 8 K. It is in a good qualitative agreement with the simulations of exciton and polariton relaxation in a kinetic model (figure 1b). Strongly excitonic (96% exciton fraction) as well as strongly photonic condensates (83% photon fraction) are realized (figure 1c). Moreover imaging of the condensate allows to evidence in-plane free propagation of the polariton condensate starting from the excitation spot. This tunability is obtained on a fully-hybrid microcavity with a high quality factor (Q>2000) and a large Rabi splitting (250 meV); it represents an important progress compared to our previous demonstration of a ZnO polariton laser in a Q=450 microcavity [2], as well as to other recent reports [3]. It also confers a strong advantage to ZnO microcavities compared to GaN [4], since strong excitonic condensates can here be investigated. Figure 1. (a) Detuning dependence of the polariton condensation threshold for a 2.5 polariton branch, under quasi-continuous excitation; (b) Polariton density at the condensation threshold deduced from the kinetic model; (c) Angle-resolved emission below and above threshold (T=300K, almost zero detuning). The authors acknowledge financial support from FP7 program through ITN networks CLERMONT4 (235114) and SPIN-OPTRONICS (237252). References [1] F. Li et al., Phys. Rev. Lett. 110, 196406 (2013) [2] T. Guillet et al., Appl. Phys. Lett. 98, 211105 (2011) [3] H. Franke et al., New J. Phys. 14, 013037 (2012); T.C. Lu et al., Optics Express 20, 5530 (2012) [4] J. Levrat et al., Phys. Rev. B 81, 125305 (2010)