In addition to their attractive technological applications in photovoltaics and light emitters, the perovskite family of semiconductors has recently emerged as an excellent excitonic material for fundamental studies. Specifically, the 2D hybrid organic-inorganic perovskite (HOIP) offers the added advantage of room temperature investigations owing to their large exciton binding energy. In this work, we strongly couple excitons in 2D HOIP crystals to planar microcavity photons sustaining exciton-polaritons under ambient conditions resulting in a Rabi splitting of 290 meV. Dark excitons directly pump the polariton branch along its dispersion in resonance with the Stokes shifted emission state (radiative pumping), creating a high density of polaritons at higher in-plane momentum (
- NSF-PAR ID:
- 10315931
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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k ||). We further probe the nonlinear polariton dispersion dynamics at varying input laser fluence, which indicates efficient polariton-polariton scattering and decay tok || = 0 from higherk ||. The observation of Stokes shift-assisted energy exchange of dark states with lower polaritons coupled with evidence of efficient polariton-polariton scattering makes 2D HOIPs an attractive platform to study exciton-polariton many-body physics and Bose-Einstein like condensation (BEC) at room temperature. -
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Abstract Room temperature stable excitons in layered two‐dimensional (2D) transition metal dichalcogenides (TMDs) offer a unique route for engineering light and matter interactions. Due to the strong optical dispersion near the excitonic transitions, a high refractive index arises in these ultrathin semiconductors.[1,2]Utilizing this behavior, strongly confined Fano type optical resonances in an ultrathin (i.e., ≈12 nm) tungsten disulfide (WS2) photonic crystal (PhC) directly fabricated on a TMD‐on‐glass platform are reported. In this approach, Fano‐type WS2photonic resonances strongly couple to the WS2excitonic dispersion engender self‐resonant exciton‐polaritons with an out‐of‐plane optical confinement exceeding that provided by surface plasmon polaritons in the visible. The large spatial light‐matter overlap endowed by this unique monolithic self‐coupling scheme is utilized for steering of enhanced 2D WSe2excitonic photoluminescence in a truly TMD integrated system. It is envisioned that the strong light matter interaction on the TMD‐on‐glass platform will unfold the prospects of ultrathin exciton‐polaritonic resonators.
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Ultralow-threshold coherent light emitters can be achieved through lasing from exciton-polariton condensates, but this generally requires sophisticated device structures and cryogenic temperatures. Polaritonic nanolasers operating at room temperature lie on the crucial path of related research, not only for the exploration of polariton physics at the nanoscale but also for potential applications in quantum information systems, all-optical logic gates, and ultralow-threshold lasers. However, at present, progress toward room temperature polariton nanolasers has been limited by the thermal instability of excitons and the inherently low quality factors of nanocavities. Here, we demonstrate room temperature polaritonic nanolasers by designing wide-gap semiconductor heterostructure nanocavities to produce thermally stable excitons coupled with nanocavity photons. The resulting mixed states of exciton polaritons with Rabi frequencies of approximately 370 meV enable persistent polariton lasing up to room temperature, facilitating the realization of miniaturized and integrated polariton systems.more » « less
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Topological photonics in strongly coupled light-matter systems offer the possibility for fabricating tunable optical devices that are robust against disorder and defects. Topological polaritons, i.e., hybrid exciton-photon quasiparticles, have been proposed to demonstrate scatter-free chiral propagation, but their experimental realization to date has been at deep cryogenic temperatures and under strong magnetic fields. We demonstrate helical topological polaritons up to 200 kelvin without external magnetic field in monolayer WS2excitons coupled to a nontrivial photonic crystal protected by pseudo time-reversal symmetry. The helical nature of the topological polaritons, where polaritons with opposite helicities are transported to opposite directions, is verified. Topological helical polaritons provide a platform for developing robust and tunable polaritonic spintronic devices for classical and quantum information-processing applications.
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In this contribution, we use heavy ion irradiation and photoluminescence (PL) spectroscopy to demonstrate that defects can be used to tailor the optical properties of two-dimensional molybdenum disulfide (MoS 2 ). Sonicated MoS 2 flakes were deposited onto Si/SiO 2 substrate and subjected to 3 MeV Au 2+ ion irradiation at room temperature to fluences ranging from 1 × 10 12 to 1 × 10 16 cm −2 . We demonstrate that irradiation-induced defects can control optical excitations in the inner core shell of MoS 2 by binding A 1s - and B 1s -excitons, and correlate the exciton peaks to the specific defects introduced with irradiation. The systematic increase of ion fluence produced different defect densities in MoS 2 , which were estimated using B/A exciton ratios and progressively increased with ion fluence. We show that up to the fluences of 1 × 10 14 cm −2 , the MoS 2 lattice remains crystalline and defect densities can be controlled, whereas at higher fluences (≥1 × 10 15 cm −2 ), the large number of introduced defects distorts the excitonic structure of the material. In addition to controlling excitons, defects were used to split bound and free trions, and we demonstrate that at higher fluences (1 × 10 15 cm −2 ), both free and bound trions can be observed in the same PL spectrum. Most importantly, the lifetimes of these states exceed trion and exciton lifetimes in pristine MoS 2 , and PL spectra of irradiated MoS 2 remains unchanged weeks after irradiation experiments. Thus, this work demonstrated the feasibility of engineering novel optical behaviors in low-dimensional materials using heavy ion irradiation. The insights gained from this study will aid in understanding the many-body interactions in low-dimensional materials and may ultimately be used to develop novel materials for optoelectronic applications.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41467-021-24925-9
