Showing papers by "Sven Höfling published in 2010"
TL;DR: In this paper, an all-optical spin echo technique was used to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds.
Abstract: Many proposed photonic quantum networks rely on matter qubits to serve as memory elements1,2. The spin of a single electron confined in a semiconductor quantum dot forms a promising matter qubit that may be interfaced with a photonic network3. Ultrafast optical spin control allows gate operations to be performed on the spin within a picosecond timescale4,5,6,7,8,9,10,11,12,13,14, orders of magnitude faster than microwave or electrical control15,16. One obstacle to storing quantum information in a single quantum dot spin is the apparent nanosecond-timescale dephasing due to slow variations in the background nuclear magnetic field15,16,17. Here we use an ultrafast, all-optical spin echo technique to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds. The ratio of decoherence time to gate time exceeds 105, suggesting strong promise for future photonic quantum information processors18 and repeater networks1,2. An ultrafast, all-optical spin echo technique is used to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds. The ratio of decoherence time to gate time exceeds 105, suggesting strong promise for future photonic quantum information processors and repeater networks.
327 citations
TL;DR: In this paper, triggered single photon emission from low mode volume electrically driven quantum dot-micropillar cavities at repetition rates of up to 220 MHz was reported. But the authors did not report on the performance of a single photon source with an optimized layout of the planar microcavity.
Abstract: We report on triggered single photon emission from low mode volume electrically driven quantum dot-micropillar cavities at repetition rates of up to 220 MHz. Due to an optimized layout of the doped planar microcavity and an advanced lateral current injection scheme, highly efficient single photon sources are realized. While g(2)(0)-values as low as 0.13±0.05 and a Purcell factor of 4 are observed for a 2.0 μm diameter micropillar, single photon emission at a rate of (35±7) MHz and an overall efficiency of (34±7)% are demonstrated for a 3.0 μm device.
208 citations
TL;DR: In this article, the authors used coherent nonlinear spectroscopy to explore a strongly coupled exciton-cavity system and measured and simulated its four-wave mixing response, allowing direct access to coherent dynamics of the first and second rungs of the Jaynes-Cummings ladder.
Abstract: In spite of their different natures, light and matter can be unified under the strong-coupling regime, yielding superpositions of the two, referred to as dressed states or polaritons. After initially being demonstrated in bulk semiconductors1 and atomic systems2, strong-coupling phenomena have been recently realized in solid-state optical microcavities3. Strong coupling is an essential ingredient in the physics spanning from many-body quantum coherence phenomena, such as Bose–Einstein condensation4 and superfluidity5, to cavity quantum electrodynamics. Within cavity quantum electrodynamics, the Jaynes–Cummings model6, 7, 8 describes the interaction of a single fermionic two-level system with a single bosonic photon mode. For a photon number larger than one, known as quantum strong coupling, a significant anharmonicity is predicted for the ladder-like spectrum of dressed states. For optical transitions in semiconductor nanostructures, first signatures of the quantum strong coupling were recently reported9. Here we use advanced coherent nonlinear spectroscopy to explore a strongly coupled exciton–cavity system10, 11. We measure and simulate its four-wave mixing response12, 13, granting direct access to the coherent dynamics of the first and second rungs of the Jaynes–Cummings ladder. The agreement of the rich experimental evidence with the predictions of the Jaynes–Cummings model is proof of the quantum strong-coupling regime in the investigated solid-state system.
154 citations
TL;DR: In this paper, positioned AlGaAs nanowires with an embedded axial heterostructure GaAs quantum dot (QD) on a prepatterned substrate have been grown.
Abstract: Positioned AlGaAs nanowires with an embedded axial heterostructure GaAs quantum dot (QD) on a prepatterned substrate have been grown. The geometry of the nanowires allows for an outcoupling of the emitted light through the nanowire tip and thereby to probe a single nanowire directly on the growth substrate. Single QD linewidths as small as 95 μeV and photon antibunching were observed at continuous wave laser excitation with a second order autocorrelation function g(2)(0)=0.46. The results represent an attractive bottom-up fabrication approach for the realization of high efficiency photonic wire based single photon sources.
89 citations
TL;DR: The effect of a magnetic field on a spinor exciton-polariton condensate has been investigated, suggesting that a dynamic condensation in the excited spin state rather than the ground spin state takes place in this magnetic field range.
Abstract: The effectof a magneticfieldon a spinor exciton-polaritoncondensate has been investigated. A quenching of a polariton Zeeman splitting and an elliptical polarization of the condensate have been observed at low magnetic fields B< 2T . The effects are attributed to a competition between the magnetic field induced circular polarization buildup and the spin-anisotropic polariton-polariton interaction which favors a linear polarization. The sign of the circular polarization of the condensate emission at B< 3T is negative, suggesting that a dynamic condensation in the excited spin state rather than the ground spin state takes placeinthismagneticfieldrange.Fromabout 2T on,theZeemansplittingopensandfromthenontheslopeof the circular polarization degree changes its sign. For magnetic fields larger than the 3 T, the upper spin state occupation is energetically suppressed and circularly polarized condensation takes place in the ground state.
79 citations
TL;DR: An effective trapping mechanism is revealed, due to the stimulated scattering gain inside the finite excitation spot combined with the short lifetime, in a GaAs-based microcavity under nonresonant excitation with an intensity-stabilized laser.
Abstract: We have performed real and momentum space spectroscopy of exciton polariton condensates in a GaAs-based microcavity under nonresonant excitation with an intensity-stabilized laser. An effective trapping mechanism is revealed, which is due to the stimulated scattering gain inside the finite excitation spot combined with the short lifetime. We observe several quantized modes while the lowest state shows Heisenberg-limited real and momentum space distributions. The experimental findings are qualitatively reproduced by an open dissipative Gross-Pitaevskii equation model.
62 citations
TL;DR: In this article, resonant tunneling diodes (RTDs) with split drain contacts have been realized and the current-voltage characteristics have been studied in the bistable regime at room temperature.
Abstract: Submicron-sized mesas of resonant tunneling diodes (RTDs) with split drain contacts have been realized and the current-voltage characteristics have been studied in the bistable regime at room temperature. Dynamically biased, the RTDs show noise-triggered firing of spikelike signals and can act as reconfigurable universal logic gates for small voltage changes of a few millivolt at the input branches. These observations are interpreted in terms of a stochastic nonlinear processes. The logic gate operation shows gain for the fired-signal bursts with transconductance slopes exceeding the thermal limit. The RTD junction can be easily integrated to arrays of multiple inputs and have thus the potential to mimic neurons in nanoelectronic circuits.
46 citations
TL;DR: A hysteretic sawtooth pattern in the free-induction decay of the single electron spin is observed and a mathematical model indicates a competition between optical nuclear pumping and nuclear spin-diffusion, potentially allowing more complex coherent control operations.
Abstract: We report the observation of a feedback process between the nuclear spins in a single charged quantum dot under coherently pulsed optical excitation and its trion transition. The optical pulse sequence intersperses resonant narrow-band pumping for spin initialization with off-resonant ultrafast pulses for coherent electron-spin rotation. A hysteretic sawtooth pattern in the free-induction decay of the single electron spin is observed; a mathematical model indicates a competition between optical nuclear pumping and nuclear spin-diffusion. This effect allows dynamic tuning of the electron Larmor frequency to a value determined by the pulse timing, potentially allowing more complex coherent control operations.
44 citations
TL;DR: In this paper, the second and third-order coherence functions of an exciton-polariton condensate were measured and compared to the theory, showing a bunching effect, but not the characteristics of a standard thermal state with g((n))(0) = n!.
Abstract: The second- and third-order coherence functions g((n))(0) (n= 2 and 3) of an exciton-polariton condensate are measured and compared to the theory. Contrary to an ideal photon laser, deviation from unity in the second- and third-order coherence functions is observed, thus showing a bunching effect, but not the characteristics of a standard thermal state with g((n))(0) = n!. The increase in bunching with the order of the coherence function, g((3))(0) > g((2))(0) > 1, indicates that the polariton condensate is different from a coherent state, a number state, or a thermal state. The measurement of third-order coherence has the advantage, compared to the second-order one, that the difference between a thermal state and a coherent state is more pronounced. The experimental results are in agreement with the theoretical model where polariton-polariton and polariton-phonon interactions are responsible for the loss of temporal coherence.
41 citations
TL;DR: In this article, the robustness of a detuned mode channel for reading out the relevant $s$-shell properties of a resonantly excited coupled quantum dot (QD) in a pillar microcavity is reported.
Abstract: We report on the robustness of a detuned mode channel for reading out the relevant $s$-shell properties of a resonantly excited coupled quantum dot (QD) in a pillar microcavity. The line broadening of the QD $s$-shell is ``monitored'' by the mode signal with high conformity to the directly measured QD linewidth. The mode signal also monitors the saturation behavior of a near Fourier transform-limited photon emission from a resonantly excited QD. We also investigate the temperature dependence of the coupling mechanism between an off-resonant QD and a cavity mode under pure resonant excitation of the quantum emitter.
40 citations
TL;DR: In this paper, the authors analyzed the contribution of different geometrical parameters, such as the number of DBR layers pairs, the amplitude of the corrugation of the pillar sidewalls, and number of etched layer pairs in the bottom DBR, on the Q versus diameter relation of high-Q semiconductor micropillar cavities.
Abstract: Micropillar cavities are potential candidates for high-efficiency single-photon sources and are testbeds for cavity quantum electrodynamics experiments. In both applications a high quality (Q) factor is desired. It was recently shown that the Q of high-Q semiconductor micropillar cavities exhibit pronounced quasi-periodic variations in the regime from 1 to 4 μm, and a detailed understanding of the variational behavior of the Q is required. Here, we study the origin of these variations using a multi-mode Fabry-Perot model appropriate for this regime. We analyze in detail contributions to the effective reflectivity of the fundamental mode arising from coupling to scattering channels involving higher-order cavity modes and propagating Bloch modes in the distributed Bragg reflectors (DBRs). We show how these weak contributions lead to strong variations of the Q factor, and we relate the average periodicity of these variations to the thickness of the DBRs and the derivative of the effective indices of the guided Bloch modes. We also examine the influence of various geometrical parameters, including the number of DBR layers pairs, the amplitude of the corrugation of the pillar sidewalls and the number of etched layer pairs in the bottom DBR on the Q versus diameter relation. Comparisons are made between extensive numerical simulations and experimental measurements, and a good qualitative agreement is found.
TL;DR: In this paper, the second-order correlation function of light emission was studied for quantum-dot micropillar lasers and the time evolution of the second order correlation function was analyzed.
Abstract: Ultrafast changes in the statistical properties of light emission are studied for quantum-dot micropillar lasers. Using pulsed excitation with varying power, we follow the time evolution of the second-order correlation function ${g}^{(2)}(t,\ensuremath{\tau}=0)$ reflecting two-photon coincidences and compare it to that of the output intensity. The previously impossible time resolution of a few picoseconds gives insight into the dynamical transition between thermal and coherent light emission. The ${g}^{(2)}$ results allow us to isolate the spontaneous and stimulated-emission contributions within an emission pulse, not accessible via the emission-intensity dynamics. Results of a microscopic theory confirm the experimental findings.
TL;DR: In this article, the oscillator strength and quantum efficiency of site-controlled InAs quantum dots nucleating on patterned nanoholes were determined by measurements on SCQD samples with varying thickness of the capping layer.
Abstract: We report on time-resolved photoluminescence spectroscopy to determine the oscillator strength (OS) and the quantum efficiency (QE) of site-controlled InAs quantum dots nucleating on patterned nanoholes. These two quantities are determined by measurements on site-controlled quantum dot (SCQD) samples with varying thickness of the capping layer. We determine radiative and nonradiative decay rates, from which we calculate an OS of 10.1±2.6 and an encouragingly high QE of (47±14)% for the SCQDs. The nonideal QE is attributed to nonradiative recombination at the etched nanohole interface.
TL;DR: In this paper, the authors presented ICLs emitting in this wavelength range that have a notably shortened injector region, with the total length of one cascade reduced by about 16% to only 63 nm.
Abstract: Interband cascade lasers (ICLs) are very attractive light sources to cover the important spectral range from 3.3 to 3.6 µm, which is of major interest for hydrocarbon detection. We present ICLs emitting in this wavelength range that have a notably shortened injector region. Compared to a well-established reference design, the total length of one cascade is reduced by about 16% to only 63 nm. The benefits are a reduction of the number of heterointerfaces, a higher intensity of the optical mode in the active region, and easier strain compensation. Threshold current densities of devices using the new injector design are cut in half throughout the temperature range of operation, compared to devices with the reference design. Deeply etched ridge waveguide devices processed from structures with 14 cascades yielded maximum operation temperatures of 73°C in pulsed operation. Peak output powers exceed 100 mW at a heat-sink temperature of 15°C.
TL;DR: In this paper, the authors measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface.
Abstract: We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy intermixing inside the quantum dots.
TL;DR: In this article, the authors report the fabrication of widely tunable monolithic quantum cascade lasers (QCLs) with coupled Fabry-Perot (FP) cavities on indium phosphide.
Abstract: The authors report the fabrication of widely tunable monolithic quantum cascade lasers (QCLs) with coupled Fabry–Perot (FP) cavities on indium phosphide. Quasicontinuous tuning of the single mode emission over a total spectral range of 242 nm was realized at two regions between 8.394 and 8.785 μm. An absorption experiment with ammonia shows principle feasibility of gas detection with multisegment QCL devices. Good agreement of the experimentally observed tuning behavior with the one expected from calculated FP mode-combs indicates that the change in the refractive index is mainly due to thermal heating as a result of current injection.
TL;DR: In this paper, a whispering gallery mode lasing in electrically driven quantum dot micropillar cavities was proposed for efficient terahertz generation via difference frequency generation.
Abstract: We report on whispering gallery mode lasing in electrically driven quantum dot micropillar cavities. The high quality microcavity structures feature whispering gallery mode emission with Q-factors up to 40 000 and laser threshold currents below 10 μA for devices with diameters between 2.6 and 5.6 μm. For large diameter micropillars a coexistence of lasing from two whispering gallery modes is realized which could be the basis for efficient terahertz generation via difference frequency generation.
TL;DR: In this paper, a detailed oscillator model is used to extract coupling parameters of the individual spin and cavity modes, which shows that the coupling depends on features of the mode symmetries.
Abstract: Semiconductor microcavities play a key role in connecting exciton states and photons in advancing quantum information in solids. In this work we report on coherent interaction between high quality microcavity photon modes and spin states of a quantum dot in the strong coupling regime of cavity quantum electrodynamics. The coupling between the photon and exciton modes is studied by varying the temperature, where the spin states are resolved with a magnetic field applied in Faraday configuration. A detailed oscillator model is used to extract coupling parameters of the individual spin and cavity modes, which shows that the coupling depends on features of the mode symmetries. Our results demonstrate an effective coupling between photon modes that is mediated by the exciton spin states.
TL;DR: In this paper, the power-dependent photoluminescence spectra from a strongly coupled quantum dot-cavity system using a quantum master equation technique that accounts for incoherent pumping, stimulated emission, pure dephasing, and fermion or boson statistics were investigated.
Abstract: We investigate the power-dependent photoluminescence spectra from a strongly coupled quantum dot-cavity system using a quantum master equation technique that accounts for incoherent pumping, stimulated emission, pure dephasing, and fermion or boson statistics. Analytical spectra at the one-photon correlation level and the numerically exact multiphoton spectra for fermions are presented. Master equation models that neglect stimulated emission processes are shown to lead to unphysical predictions at high powers, such as negative mean photon numbers. We compare to recent experiments on a quantum dot-micropillar cavity system and show that an excellent fit to the data can be obtained by varying only the incoherent pump rates in direct correspondence with the experiments. Our theory and experiments together show convincing evidence for stimulated-emission induced broadening and anharmonic cavity quantum electrodynamics.
TL;DR: In this article, a combined experimental and theoretical study of the polarization-dependent strong-coupling regime between two quantum dots and an asymmetric micropillar cavity is presented. And the authors apply an analytical photon Green function approach that successfully reproduces the qualitative features of their experimental data.
Abstract: We present a combined experimental and theoretical study of the polarization-dependent strong-coupling regime between two quantum dots and an asymmetric micropillar cavity. The photoluminescence emission demonstrates that the fundamental cavity mode is split into two linearly polarized cavity modes, both of which are coupled to 45%-aligned quantum dot excitons. We map out various single-exciton and double-exciton coupling regimes, including the full energy dispersion of dual-exciton and dual-cavity emission under $x$ and $y$ detection angle. To explain the complex light-matter coupling we apply an analytical photon Green function approach that successfully reproduces the qualitative features of our experimental data.
TL;DR: In this article, it was shown that the violet shift of the polariton emission line at the condensation threshold significantly exceeds the energy of the repulsive interaction between polaritons in the condensate.
Abstract: Condensation of exciton polaritons in planar microcavities with GaAs/AlAs quantum wells in the active area has been studied. It has been found that an increase in the lifetime of polaritons up to ∼10–15 ps when the Q factor of a microcavity exceeds 7000 makes it possible to detect Bose-Einstein condensation of polaritons with a dominant (>90%) photon component. Condensation occurs under thermodynamically nonequilibrium conditions in lateral traps with diameters ∼10 μm formed due to long-range fluctuations of the polariton potential. The violet shift of the polariton emission line at the condensation threshold significantly exceeds the energy of the repulsive interaction between polaritons in the condensate. It has been shown that the shift is mainly due to a decrease in the oscillator strength of bright excitons in lateral traps, caused by the localization of photoexcited long-living dark excitons.
TL;DR: In this article, a micropillar cavity with a quality factor of 10,000 and a diameter of 1.9μm was used to realize strong coupling under electrical carrier injection.
Abstract: Integrating In0.3Ga0.7As quantum dots (QDs) featuring a high oscillator strength into a high quality electrically contacted micropillar cavity enabled us to realize strong coupling under electrical carrier injection. In the micropillar cavity with a quality factor of 10 000 and a diameter of 1.9 μm, a vacuum Rabi splitting of 108 μeV was observed when an electrically excited QD exciton was tuned through resonance with the fundamental cavity mode by varying the temperature.
TL;DR: This paper presents a systematic investigation of strain compensation schemes for InAs/AlSb superlattices (SLs) on GaSb substrates and finds that each approach yields layers with excellent crystal quality and minimal intermixing at the heterointerfaces as verified by high resolution x-ray diffraction analysis and transmission electron microscopy.
Abstract: This paper presents a systematic investigation of strain compensation schemes for InAs/AlSb superlattices (SLs) on GaSb substrates. Short growth interruptions (soak times) under varying arsenic and/or antimony beam equivalent pressures in InAs/AlSb SLs with exemplary dimensions of about ((2.4/2.4) ± 0.2) nm were investigated to achieve strain compensation. When using uncracked As4, strain compensation was found to be unaccomplishable unless sub-monolayer AlAs spikes were inserted at the interface. In contrast, the supply of cracked As2 dimers leads directly to the formation of strain compensating AlAs-like interfaces. This mechanism allows various growth sequences for strain compensated superlattices, including soak-time-free and Sb-soak-only SL growth. Each of the two latter approaches yields layers with excellent crystal quality and minimal intermixing at the heterointerfaces as verified by high resolution x-ray diffraction analysis and transmission electron microscopy.
TL;DR: The variation of the spontaneous emission rate with polarization for self-assembled single quantum dots in two-dimensional photonic crystal membranes is measured and a maximum anisotropy factor of 6 is obtained between the decay rates of the two nondegenerate bright states.
Abstract: We have measured the variation of the spontaneous emission rate with polarization for self-assembled single quantum dots in two-dimensional photonic crystal membranes. We observe a maximum anisotropy factor of 6 between the decay rates of the two bright exciton states. This large anisotropy is attributed to the substantially different projected local density of optical states for differently oriented dipoles in the photonic crystal.
TL;DR: In this paper, the emission properties of single molecular-beam-epitaxially grown InGaAs/GaAs quantum dashes were investigated and it was revealed that a decreased exciton to biexciton radiative lifetimes ratio was a fingerprint of a weak carrier confinement.
Abstract: We report on the emission properties of single molecular-beam-epitaxially grown InGaAs/GaAs quantum dashes. Supported by a few level rate equation model it has been revealed a decreased exciton to biexciton radiative lifetimes ratio being a fingerprint of a weak carrier confinement. Furthermore, a biexciton sideband, connected with the Coulomb interaction of quantum dash biexciton with excitons confined in the wetting layer (WL), has been observed in photoluminescence (PL). Both the effects have found a confirmation in direct measurements of PL decay times, including long radiative lifetimes of the WL states which appeared to have a localized character.
TL;DR: In this article, the fabrication and characterization of single-electron memories based on site-controlled InAs quantum dots (QDs) embedded in a GaAs/AlGaAs quantum-wire transistor is presented.
Abstract: The authors report on the fabrication and characterization of single-electron memories based on site-controlled InAs quantum dots (QDs) embedded in a GaAs/AlGaAs quantum-wire transistor. By using a hole structure template on a modulation-doped GaAs/AlGaAs heterostructure in combination with etching techniques, two single InAs QDs were centrally positioned in a quantum-wire transistor so that pronounced shifts of the transistor threshold occur by charging of the QDs with single electrons. Single-electron read and write functionalities up to room temperature were observed. The memory function can be also controlled by light with a wavelength in the telecommunication range.
TL;DR: In this article, the optical transitions in tunnel-injection structures were investigated by contactless electroreflectance and it was shown that there exist electron and hole states which are localized on both sides of such an asymmetric confinement potential.
Abstract: Tunnel-injection structures composed of an In0.53Ga0.47As/In0.53Ga0.23Al0.24As quantum well (QW) and a layer of InAs quantum dashes (QDashes) separated by In0.53Ga0.23Al0.24As barriers of various thicknesses have been investigated by contactless electroreflectance. The observed spectral features have been explained taking into account the optical transitions in a combined system of In0.53Ga0.47As QW and InAs QDash wetting layer. It has been shown that there exist electron and hole states which are localized on both sides of such an asymmetric confinement potential. The latter has allowed concluding that the QDash region in tunnel-injection structures can be easily penetrated by the carriers due to the presence of the wetting layer in the self-assembled structure.
TL;DR: In this paper, the growth of Interband Cascade Laser material to cover the wavelength range from 3-4-μm is presented along with the fabrication and characterization of Broad Area (BA) and Ridge Waveguide (RWG) devices based on this material.
Abstract: The growth of Interband Cascade Laser material to cover the wavelength range from 3–4 μm is presented along with the fabrication and characterization of Broad Area (BA) and Ridge Waveguide (RWG) devices based on this material. Pulsed operation slightly below room temperature is observed for both device types, and a strong reduction of threshold currents can be observed in the RWG lasers. Variation of the active Quantum Well width in the epitaxial structures enables laser emission in the 3–4 μm wavelength region.
11 Feb 2010
TL;DR: In this paper, the authors applied coherent nonlinear spectroscopy to explore a strongly coupled exciton-cavity system and measured and simulated its four-wave mixing (FWM) response, granting direct access to the first two rungs of the JC ladder.
Abstract: Light and matter can be unified under the strong coupling regime, creating superpositions of both, called dressed states or polaritons. After initially being demonstrated in bulk semiconductors and atomic systems ,strong coupling phenomena have been realized in solid state optical microcavities. They form an essential ingredient in the exciting physics spanning from many-body quantum coherence phenomena, like Bose-Einstein condensation and superfluidity, to cavity quantum electrodynamics (cQED). A widely used approach within cQED is the Jaynes-Cummings (JC) model that describes the interaction of a single fermionic two-level system with a single bosonic photon mode. For a photon number larger than one, known as quantum strong coupling (QSC), a significant anharmonicity is predicted for the ladder-like spectrum of dressed states. For optical transitions in semiconductor nanostructures, first signatures of the quantum strong coupling were recently published. In our latest report we applied advanced coherent nonlinear spectroscopy to explore a strongly coupled exciton-cavity system. Specifically, we measured and simulated its four-wave mixing (FWM) response, granting direct access to the first two rungs of the JC ladder. This paper summarizes the main results of Ref. 15 and adds FWM experiments obtained on a micropillar cavity in which a doublet of quantum dot (QD) excitons interacts with the cavity mode in the limit of weak to strong coupling.
TL;DR: In this article, a GaInAsSb-GaSb quantum-well diode laser with a single device tuning range of 60 nm is presented, which is achieved by the implementation of binary superimposed metal gratings.
Abstract: GaInAsSb-GaSb quantum-well diode lasers emitting around 2.80 μm with a single device tuning range of 60 nm are presented. This was achieved by the implementation of binary superimposed metal gratings. The lasers work at room temperature in continuous-wave mode and show tunable single-mode emission with a sidemode suppression ratio of more than 30 dB. The optical output power of more than 1 mW makes them suitable for gas sensing.