16 research outputs found
Tunable cavity coupling of the zero phonon line of a nitrogen-vacancy defect in diamond
We demonstrate the tunable enhancement of the zero phonon line of a single
nitrogen-vacancy color center in diamond at cryogenic temperature. An open
cavity fabricated using focused ion beam milling provides mode volumes as small
as 1.24 m. In-situ tuning of the cavity resonance is achieved with
piezoelectric actuators. At optimal coupling of the full open cavity the signal
from individual zero phonon line transitions is enhanced by about a factor of
10 and the overall emission rate of the NV center is increased by 40%
compared with that measured from the same center in the absence of cavity field
confinement. This result is important for the realization of efficient
spin-photon interfaces and scalable quantum computing using optically
addressable solid state spin qubits.Comment: 11 pages Main Article + 4 pages Supplementary Info Typos fixed from
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Valley-addressable polaritons in atomically thin semiconductors
The locking of the electron spin to the valley degree of freedom
in transition metal dichalcogenide (TMD) monolayers has seen
these materials emerge as a promising platform in valleytronics.
When embedded in optical microcavities, the large oscillator
strengths of excitonic transitions in TMDs allow the
formation of polaritons that are part-light part-matter quasiparticles.
Here, we report that polaritons in MoSe2 show an
efficient retention of the valley pseudospin contrasting them
with excitons and trions in this material. We find that the
degree of the valley pseudospin retention is dependent on
the photon, exciton and trion fractions in the polariton states.
This allows us to conclude that in the polaritonic regime,
cavity-modified exciton relaxation inhibits loss of the valley
pseudospin. The valley-addressable exciton-polaritons and
trion-polaritons presented here offer robust valley-polarized
states with the potential for valleytronic devices based on
TMDs embedded in photonic structures and valley-dependent
nonlinear polariton–polariton interactions
Spectral engineering of coupled open-access microcavities
Open-access microcavities are emerging as a new approach to confine and engineer light at mode volumes down to the λ3 regime. They offer direct access to a highly confined electromagnetic field while maintaining tunability of the system and flexibility for coupling to a range of matter systems. This article presents a study of coupled cavities, for which the substrates are produced using Focused Ion Beam milling. Based on experimental and theoretical investigation the engineering of the coupling between two microcavities with radius of curvature of 6 inline imagem is demonstrated. Details are provided by studying the evolution of spectral, spatial and polarisation properties through the transition from isolated to coupled cavities. Normal mode splittings up to 20 meV are observed for total mode volumes around inline image. This work is of importance for future development of lab-on-a-chip sensors and photonic open-access devices ranging from polariton systems to quantum simulators
Diffusion-driven continuous-wave-pumped organic dye lasers
We report on the realisation of ultra-small-modevolume tunable dye lasers based on hemispherical open microcavities. The cavity mode volume is of the order of cubic micrometers, such that self-diffusion of the dye molecules allows continuous wave operation over several minutes without the need for driven circulation. Such micro lasers could be integrated into lab-on-a-chip devices. A rate-equation model that incorporates the diffusion mechanism is used to predict the effect of the microcavity parameters on the lasing threshold
Diffusion-driven continuous-wave-pumped organic dye lasers
We report on the realisation of ultra-small-modevolume tunable dye lasers based on hemispherical open microcavities. The cavity mode volume is of the order of cubic micrometers, such that self-diffusion of the dye molecules allows continuous wave operation over several minutes without the need for driven circulation. Such micro lasers could be integrated into lab-on-a-chip devices. A rate-equation model that incorporates the diffusion mechanism is used to predict the effect of the microcavity parameters on the lasing threshold
Universal scaling in the dynamic hysteresis, and non-Markovian dynamics, of a tunable optical cavity
We investigate, experimentally and theoretically, the dynamics of a laser-driven cavity with noninstantaneous effective photon-photon interactions. Scanning the laser-cavity frequency detuning at different speeds across an optical bistability, we find a hysteresis area that is a nonmonotonic function of the speed. In the limit of fast scans comparable to the memory time of the interactions, we demonstrate that the hysteresis area decays following a universal power law with scaling exponent -1. We further demonstrate a regime of non-Markovian dynamics emerging from white noise. This regime is evidenced by peaked distributions of residence times in the metastable states of our system. Our results offer new perspectives for exploring the physics of scaling, universality, and metastability, in non-Markovian regimes using arrays of bistable optical cavities with low quality factors, driven by low laser powers, and at room temperature
Room temperature exciton-polaritons with two-dimensional WS2
Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant
potential for optoelectronic devices. In particular they are suited for cavity quantum
electrodynamics in which strong coupling leads to polariton formation as a root to realisation of
inversionless lasing, polariton condensation and superfluidity. Demonstrations of such strongly
correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities
and were frequently impaired by strong material disorder. At room-temperature, experiments
approaching the strong coupling regime with transition metal dichalcogenides have been reported,
but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer
WS2 coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates
are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi
splitting of ~ΩRabi = 70 meV, exceeding the exciton linewidth. Our data are well described by
a transfer matrix model appropriate for the large linewidth regime. This work provides a platform
towards observing strongly correlated polariton phenomena in compact photonic devices for
ambient temperature applications
Room temperature exciton-polaritons with two-dimensional WS2
Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensation and superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS2 coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of ~ΩRabi = 70 meV, exceeding the exciton linewidth. Our data are well described by a transfer matrix model appropriate for the large linewidth regime. This work provides a platform towards observing strongly correlated polariton phenomena in compact photonic devices for ambient temperature applications
Microcavity enhanced single photon emission from two-dimensional WSe2
Atomically flat semiconducting materials such as monolayer WSe2 hold great promise for novel optoelectronic devices. Recently, quantum light emission has been observed from bound excitons in exfoliated WSe2. As part of developing optoelectronic devices, the control of the radiative properties of such emitters is an important step. Here, we report the coupling of a bound exciton in WSe2 to open microcavities. We use a range of radii of curvature in the plano-concave cavity geometry with mode volumes in the λ3 regime, giving Purcell factors of up to 8 while increasing the photon flux five-fold. Additionally, we determine the quantum efficiency of the single photon emitter to be η=0.46±0.03. Our findings pave the way to cavity-enhanced monolayer based single photon sources for a wide range of applications in nanophotonics and quantum information technologies
Microcavity enhanced single photon emission from two-dimensional WSe2
Atomically flat semiconducting materials such as monolayer WSe2 hold great promise for novel optoelectronic devices. Recently, quantum light emission has been observed from bound excitons in exfoliated WSe2. As part of developing optoelectronic devices, the control of the radiative properties of such emitters is an important step. Here, we report the coupling of a bound exciton in WSe2 to open microcavities. We use a range of radii of curvature in the plano-concave cavity geometry with mode volumes in the λ3 regime, giving Purcell factors of up to 8 while increasing the photon flux five-fold. Additionally, we determine the quantum efficiency of the single photon emitter to be η=0.46±0.03. Our findings pave the way to cavity-enhanced monolayer based single photon sources for a wide range of applications in nanophotonics and quantum information technologies