Showing papers on "Spontaneous emission published in 2008"
TL;DR: A measurement using a one-electron quantum cyclotron gave the electron magnetic moment in Bohr magnetons, g/2=1.001 159 652 180 73 (28) [0.28 ppt], with an uncertainty 2.7 and 15 times smaller than for previous measurements in 2006 and 1987.
Abstract: A measurement using a one-electron quantum cyclotron gives the electron magnetic moment in Bohr magnetons, g/2=1.001 159 652 180 73 (28) [0.28 ppt], with an uncertainty 2.7 and 15 times smaller than for previous measurements in 2006 and 1987. The electron is used as a magnetometer to allow line shape statistics to accumulate, and its spontaneous emission rate determines the correction for its interaction with a cylindrical trap cavity. The new measurement and QED theory determine the fine structure constant, with alpha{-1}=137.035 999 084 (51) [0.37 ppb], and an uncertainty 20 times smaller than for any independent determination of alpha.
946 citations
TL;DR: In this article, the surface plasmons (SPs) have attracted much attentions because optical properties can be greatly enhanced by coupling between SPs and the multiple quantum wells (MQWs) in light-emitting diodes(LEDs).
Abstract: Surface plasmons (SPs) have attracted much attentions because optical properties can be greatly enhanced by coupling between SPs and the multiple quantum wells(MQWs) in light-emitting diodes(LEDs). We demonstrate the SP enhanced InGaN/GaN MQW blue LED with an Ag nanoparticle layer located underneath the MQWs. An enhancement of 32.2% of optical output power of the LED was observed at an input current of 100 mA. The time resolvedphotoluminescence(PL) result showed that the PL decay time of the LED with Ag nanoparticles was significantly decreased compared to that of the LED without Ag nanoparticles, indicating that the spontaneous emission rate was increased by the energy transfer between the QW light emitter and the SP of Ag nanoparticle. This result shows that the Ag nanoparticles can be used to greatly increase the internal quantum efficiency of InGaN/GaN MQW blue LED through the coupling of excitons in MQWs and SPs in Ag nanoparticles.
468 citations
TL;DR: It is found that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model.
Abstract: We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the spontaneous qubit decay into a microwave transmission-line cavity can accurately predict the qubit lifetimes over 2 orders of magnitude in time and more than an octave in frequency. Coherence times T1 and T_{2};{*} of more than a microsecond are reproducibly demonstrated.
461 citations
TL;DR: Time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides are presented, and an unprecedented large bandwidth of 20 nm is demonstrated, showing the promising potential of photonic crystals waveguide for efficient single-photon sources.
Abstract: We present time-resolved spontaneous emission measurements of single quantum dots embedded in photonic crystal waveguides. Quantum dots that couple to a photonic crystal waveguide are found to decay up to 27 times faster than uncoupled quantum dots. From these measurements beta-factors of up to 0.89 are derived, and an unprecedented large bandwidth of 20 nm is demonstrated. This shows the promising potential of photonic crystal waveguides for efficient single-photon sources. The scaled frequency range over which the enhancement is observed is in excellent agreement with recent theoretical proposals taking into account that the light-matter coupling is strongly enhanced due to the significant slow-down of light in the photonic crystal waveguides.
348 citations
TL;DR: In this paper, the carrier distribution in multi quantum well (multi-QW) InGaN light-emitting diodes was studied and it was shown that, no matter how many QWs are grown, only the QW nearest the p layer emits light under electrical pumping, which can limit the performances of high power devices.
Abstract: We study the carrier distribution in multi quantum well (multi-QW) InGaN light-emitting diodes. Conventional wisdom would assume that a large number of QWs lead to a smaller carrier density per QW, enabling efficient carrier recombination at high currents. We use angle-resolved far-field measurements to determine the location of spontaneous emission in a series of multi-QW samples. They reveal that, no matter how many QWs are grown, only the QW nearest the p layer emits light under electrical pumping, which can limit the performances of high-power devices.
326 citations
04 May 2008
TL;DR: In this paper, the authors observed stimulated emission of surface plasmon polaritons propagating at the interface between a silver film and a film of optically pumped polymethyl methacrylate (PMMA) doped with rhodamine 6G (R6G) dye.
Abstract: We have observed stimulated emission of surface plasmon polaritons (SPPs) propagating at the interface between a silver film and a film of optically pumped polymethyl methacrylate (PMMA) doped with rhodamine 6G (R6G) dye.
302 citations
TL;DR: 3D numerical calculations demonstrate that the interaction of a single quantum emitter with the electromagnetic field is both enhanced and directed by a nano-optical Yagi-Uda antenna, making such antennas a promising candidate for compact easy-to-address planar sensors.
Abstract: We demonstrate by 3D numerical calculations that the interaction of a single quantum emitter with the electromagnetic field is both enhanced and directed by a nano-optical Yagi-Uda antenna. The single emitter is coupled in the near field to the resonant plasmon mode of the feed element, enhancing both excitation and emission rates. The angular emission of the coupled system is highly directed and determined by the antenna mode. Arbitrary control over the main direction of emission is obtained, regardless of the orientation of the emitter. The directivity is even more increased by the presence of a dielectric substrate, making such antennas a promising candidate for compact easy-to-address planar sensors.
289 citations
TL;DR: A broadband femtosecond laser is applied that redistributes the vibrational population in the ground state via a few electronic excitation/spontaneous emission cycles and observes a fast and efficient accumulation in the lowest vibrational level, ν = 0, of the singlet electronic state.
Abstract: The methods producing cold molecules from cold atoms tend to leave molecular ensembles with substantial residual internal energy. For instance, cesium molecules initially formed via photoassociation of cold cesium atoms are in several vibrational levels ν of the electronic ground state. We applied a broadband femtosecond laser that redistributes the vibrational population in the ground state via a few electronic excitation/spontaneous emission cycles. The laser pulses are shaped to remove the excitation frequency band of the ν = 0 level, preventing re-excitation from that state. We observed a fast and efficient accumulation (∼70% of the initially detected molecules) in the lowest vibrational level, ν = 0, of the singlet electronic state. The validity of this incoherent depopulation pumping method is very general and opens exciting prospects for laser cooling and manipulation of molecules.
257 citations
TL;DR: In this article, the optical power evolves from a superlinear to a linear regime as the pump power exceeds threshold, concomitant with a transition to directional emission along the nanowire and the emergence of well defined cavity Fabry-Perot modes around a wavelength of ≈385nm, the intensity of which exceeds the spontaneous emission background by orders of magnitude.
Abstract: Direct evidence of the transition from amplified spontaneous emission to laser action in optically pumped zinc oxide (ZnO) nanowires, at room temperature, is presented. The optical power evolves from a superlinear to a linear regime as the pump power exceeds threshold, concomitant with a transition to directional emission along the nanowire and the emergence of well defined cavity Fabry–Perot modes around a wavelength of ≈385 nm, the intensity of which exceeds the spontaneous emission background by orders of magnitude. The laser oscillation threshold is found to be strongly dependent on nanowire diameter, with no laser oscillation observed for diameters smaller than ∼150 nm. Finally, we use an alternative “head on” detection geometry to measure the output power of a single nanowire laser.
251 citations
TL;DR: In this article, the spontaneous emission process of an optical, dipolar emitter in metal-dielectric-metal slab and slot waveguide structures was theoretically investigated, and it was shown that both structures exhibit strong emission enhancements at nonresonant conditions, due to the tight confinement of modes between two metallic plates.
Abstract: We theoretically investigate the spontaneous emission process of an optical, dipolar emitter in metal-dielectric-metal slab and slot waveguide structures. We find that both structures exhibit strong emission enhancements at nonresonant conditions, due to the tight confinement of modes between two metallic plates. The large enhancement of surface plasmon-polariton excitation enables dipole emission to be preferentially coupled into plasmon waveguide modes. These structures find applications in creating nanoscale local light sources or in generating guided single plasmons in integrated optical circuits.
182 citations
TL;DR: The correlated spontaneous emission from a dense spherical cloud of N atoms uniformly excited by absorption of a single photon is studied to find that the decay of such a state depends on the relation between an effective Rabi frequency Omega proportional square root N and the time of photon flight through the cloud R/c.
Abstract: We study the correlated spontaneous emission from a dense spherical cloud of N atoms uniformly excited by absorption of a single photon. We find that the decay of such a state depends on the relation between an effective Rabi frequency Omega proportional square root N and the time of photon flight through the cloud R/c. If OmegaR/c >1, the coupled atom-radiation system oscillates between the collective Dicke state (with no photons) and the atomic ground state (with one photon) with frequency Omega while decaying at a rate c/R.
TL;DR: In this paper, it was shown that when an electron relaxes from an excited state, it generates not one but two photons, which has been seen in atomic systems, but never in semiconductors, until now.
Abstract: It is possible that when an electron relaxes from an excited state, it generates not one but two photons. Such two–photon emission has been seen in atomic systems, but never in semiconductors, until now. The experimental observation could have intriguing implications for quantum optics.
TL;DR: In this article, a novel gain media based on staggered InGaN quantum wells (QWs) grown by metal-organic chemical vapor deposition was demonstrated as improved active region for visible light emitters.
Abstract: A novel gain media based on staggered InGaN quantum wells (QWs) grown by metal-organic chemical vapor deposition was demonstrated as improved active region for visible light emitters. Fermi's golden rule indicates that InGaN QW with step-function like In content in the well leads to significantly improved radiative recombination rate and optical gain due to increased electron-hole wavefunction overlap, in comparison to that of conventional InGaN QW. Spontaneous emission spectra of both conventional and staggered InGaN QW were calculated based on energy dispersion and transition matrix element obtained by 6-band k middotp formalism for wurtzite semiconductor, taking into account valence-band-states mixing, strain effects, and polarization-induced electric fields. The calculated spectra for the staggered InGaN QW showed enhancement of radiative recombination rate, which is in good agreement with photoluminescence and cathodoluminescence measurements at emission wavelength regime of 425 and 500 nm. Experimental results of light-emitting diode (LED) structures utilizing staggered InGaN QW also show significant improvement in output power. Staggered InGaN QW allows polarization engineering leading to improved luminescence intensity and LED output power as a result of enhanced radiative recombination rate.
TL;DR: In this paper, the radiative and nonradiative decay rates of InAs quantum dots are measured by controlling the local density of optical states near an interface, and from time-resolved measurements, they extract the oscillator strength and the quantum efficiency and their dependence on emission energy.
Abstract: The radiative and nonradiative decay rates of InAs quantum dots are measured by controlling the local density of optical states near an interface. From time-resolved measurements, we extract the oscillator strength and the quantum efficiency and their dependence on emission energy. From our results and a theoretical model, we determine the striking dependence of the overlap of the electron and hole wavefunctions on the quantum dot size. We conclude that the optical quality is best for large quantum dots, which is important in order to optimally tailor quantum dot emitters for, e.g., quantum electrodynamics experiments
TL;DR: In this paper, a theory of the intrinsic linewidths of laser output of single-mode quantum-cascade (QC) lasers in mid-infrared and terahertz (THz) ranges is developed.
Abstract: We have developed a theory of the intrinsic linewidths of laser output of single-mode quantum-cascade (QC) lasers in mid-infrared and terahertz (THz) ranges. In the theoretical treatment, the concept of an effective coupling efficiency of spontaneous emission, given by a fractional rate of spontaneous emission coupled into a lasing mode to total nonlasing relaxation, is introduced to clarify a hidden reason for the narrowness of the linewidths. A narrow linewidth (12-kHz) reported with a frequency-stabilized 8.5- distributed-feedback QC laser is successfully interpreted in terms of an extremely small effective coupling efficiency of spontaneous emission, caused by ultrafast nonradiative scatterings. The present theory predicts the presence of a minimum ldquolinewidth floorrdquo in a high-injection-current region and the independence of linewidth on detuning between gain-peak and emission wavelengths. The theoretical treatment is expanded to derive the further modified Schawlow-Townes formula including the line-broadening by black body radiation in a THz QC laser. The linewidth of a THz QC laser is predicted to be considerably broadened by black body radiation.
TL;DR: In this paper, a visible gain medium based on type-II InGaNGaNAs QW with significantly enhanced transition matrix element, which will lead to large improvement in its optical gain and radiative recombination rate.
Abstract: conventional InGaN /GaN QW is the large spontaneous and piezoelectric polarization fields in QW. These lead to charge separation, which significantly reduce the optical gain of the QW. To minimize electrostatic field, nonpolar InGaN material growths have been pursued. 3 Approaches to minimize the charge separation effect via -AlGaN layer in InGaN QW 4 and staggered InGaN QW 5,6 with improved electron-hole wavefunction overlap ehh, have resulted in improvement in the efficiency and output power of LEDs. In this paper, we present a visible gain medium based on type-II InGaNGaNAs QW with significantly enhanced transition matrix element, which will lead to large improvement in its optical gain and radiative recombination rate. Based on Fermi’s Golden Rule, the radiative recombination rate of the interband transition is proportional to the square of the ehh. In conventional type-I InGaN QW, the spontaneous and piezoelectric polarization fields result in energy band-bending, which leads to charge separation in QW. By engineering the energy band lineup and polarization field using nitride-based type-II QW with improved overlap ehh, its radiative recombination rate and optical gain of
TL;DR: The first enhanced extraction biosensor that allows for over 20-fold enhancement of the fluorescence signal in detection of the cytokine TNF-alpha by a fluorescence sandwich immunoassay is demonstrated.
Abstract: Efficient recovery of light emitted by fluorescent molecules by employing photonic structures can result in high signal-to-noise ratio detection for biological applications including DNA microarrays, fluorescence microscopy and single molecule detection By employing a model system comprised of colloidal quantum dots, we consider the physical basis of the extraction effect as provided by photonic crystals Devices with different lattice symmetry are fabricated ensuring spectral and spatial coupling of quantum dot emission with leaky eigenmodes and the emission characteristics are studied using angle-resolved and angle-integrated measurements Comparison with numerical calculations and lifetime measurements reveals that the enhancement occurs via resonant redirection of the emitted radiation Comparison of various lattices reveals differences in the enhancement factor with a maximum enhancement factor approaching 220 We also demonstrate the first enhanced extraction biosensor that allows for over 20-fold enhancement of the fluorescence signal in detection of the cytokine TNF-α by a fluorescence sandwich immunoassay
TL;DR: In this article, a self-consistent analysis of type-II InGaN-GaNAs quantum wells with thin dilute-As (∼3%) GaNAs layer is performed.
Abstract: Type-II InGaN–GaNAs quantum wells (QWs) with thin dilute-As (∼3%) GaNAs layer are analyzed self-consistently as improved III-nitride gain media for diode lasers. The band structure is calculated by using a six-band k⋅p formalism, taking into account valence band mixing, strain effect, spontaneous and piezoelectric polarizations, as well as the carrier screening effect. The type-II InGaN–GaNAs QW structure allows large electron-hole wave function overlap by confining the hole wave function in the GaNAs layer of the QW. The findings based on self-consistent analysis indicate that type-II InGaN-GaNAs QW active region results in superior performance for laser diodes, in comparison to that of conventional InGaN QW. Both the spontaneous emission radiative recombination rate and optical gain of type-II InGaN–GaNAs QW structure are significantly enhanced. Reduction in the threshold current density of InGaN–GaNAs QW lasers is also predicted.
TL;DR: In this paper, an overview of the recent progress in the modification of fluorescence when an emitter is placed close to a nanostructure is presented, in order to control the wealth of parameters that contribute to this process.
Abstract: The coupling of nanostructures with emitters opens up ways for the realization of man-made subwavelength light emitting elements. In this article we present an overview of our recent progress in the modification of fluorescence when an emitter is placed close to a nanostructure. In order to control the wealth of parameters that contribute to this process, we have combined scanning probe technology with single molecule microscopy and spectroscopy. We discuss the enhancement and reduction of molecular excitation and emission rates in the presence of a dielectric or metallic nanoparticle and emphasize the role of plasmon resonances in the latter. Furthermore, we examine the spectral and angular emission characteristics of the molecule–particle system. The experimental findings are in excellent semi-quantitative agreement with the outcome of theoretical calculations. We show that the interaction of an emitter with a nanoparticle can be expressed in the framework of an optical nanoantennae and propose arrangem...
TL;DR: In this paper, the authors studied the emission of a single photon from a spherically symmetric cloud of atoms and presented an exact analytical expression for eigenvalues and eigenstates of this many-body problem.
Abstract: We study emission of a single photon from a spherically symmetric cloud of $N$ atoms (one atom is excited; $N\ensuremath{-}1$ are in the ground state) and present an exact analytical expression for eigenvalues and eigenstates of this many-body problem. We found that some states decay much faster than the single-atom decay rate, while other states are trapped and undergo very slow decay. When the size of the atomic cloud is small compared with the radiation wavelength, we found that the radiation frequency undergoes a large shift.
TL;DR: In this paper, a scheme for the deterministic generation of three-dimensional entanglement of two distant atoms separately trapped in two optical cavities connected by an optical fiber was proposed.
Abstract: A scheme is proposed for the deterministic generation of three-dimensional entanglement of two distant atoms separately trapped in two optical cavities connected by an optical fiber. Employing adiabatic passage along dark states, the atoms are always in ground states, in particular, the fiber mode remains in the vacuum state due to the quantum destructive interference, and the population of the cavities being excited can be negligible under certain conditions. In this sense, our scheme constructs an effective way to avoid the atomic spontaneous emission and the decays of fiber and cavities.
TL;DR: It is shown that a three-level lambda quantum emitter with equal spontaneous emission rates on both optically active transitions can absorb an incident single-photon pulse with a probability approaching unity, provided that the focused light profile matches that of the emitter dipole emission.
Abstract: We show that a three-level lambda quantum emitter with equal spontaneous emission rates on both optically active transitions can absorb an incident single-photon pulse with a probability approaching unity, provided that the focused light profile matches that of the emitter dipole emission. Even with realistic focusing geometries, our results could find applications in long-distance entanglement of spin qubits.
TL;DR: It is shown that, for nanowires with divergent output beams, the introduction of a conical tapering with a small opening angle reduces the beam divergence and increases transmission, which results in a dramatic increase in the collection efficiency of the detection optics.
Abstract: The influence of a tapering on nanowire light-emission profiles is studied. We show that, for nanowires with divergent output beams, the introduction of a conical tapering with a small opening angle reduces the beam divergence and increases transmission. This results in a dramatic increase in the collection efficiency of the detection optics. For a realistic tapering and a modest NA, the collection efficiency is enhanced by more than a factor of 2. This improvement is ensured by the adiabatic expansion of the guided mode in the tapering.
TL;DR: In this article, low threshold lasing in electrically pumped quantum dot-micropillar cavities with quality factors exceeding 10.000 was reported. But the authors did not consider the effect of the number of quantum dots in the active layer.
Abstract: We report on low threshold lasing in electrically pumped quantum dot-micropillar cavities. Lasing action associated with threshold currents as low as 8μA at 10K is observed for micropillar cavities with quality factors exceeding 10.000. Due to an optimized contact scheme lasing is achieved for pillar structures with diameters as small as 1.5μm, containing on average less than 100 quantum dots in the active layer. The transition from spontaneous to stimulated emission is confirmed by autocorrelation measurements which reveal pronounced photon bunching near threshold.
TL;DR: A nitrogen-vacancy (NV-) colour centre based single photon source based on cavity Purcell enhancement of the zero phonon line and suppression of other transitions has striking performance, including effective lifetime of 70 ps, linewidth of 0.01 nm, near unit single photon emission probability and small multi-photon probability.
Abstract: We analyze a nitrogen-vacancy (NV-) colour centre based single photon source based on cavity Purcell enhancement of the zero phonon line and suppression of other transitions. Optimal performance conditions of the cavity-centre system are analyzed using Master equation and quantum trajectory methods. By coupling the centre strongly to a high-finesse optical cavity [Q approximately O(10(4) - 10(5)), V approximately lambda (3)] and using sub-picosecond optical excitation the system has striking performance, including effective lifetime of 70 ps, linewidth of 0.01 nm, near unit single photon emission probability and small [O(10(-5))] multi-photon probability.
TL;DR: In this paper, the spontaneous emission peak with increasing injection current was examined in blue laser diodes fabricated on m- and c-plane GaN substrates, and the results confirmed that the blueshift in quantum-wells fabricated on M-plane oriented substrates is smaller than on C-plane-oriented substrates due to the absence of polarization induced electric fields.
Abstract: Blue laser diodes (LDs) were fabricated on m-plane oriented GaN substrates by atmospheric-pressure metalorganic chemical vapor deposition. Typical threshold current for stimulated emission at a wavelength λ of 463 nm was 69 mA. Blueshift of the spontaneous emission peak with increasing injection current was examined in LDs fabricated on m- and c-plane GaN substrates. Blueshifts for the m-plane LD (λ=463 nm) and the c-plane LD (λ=454 nm) with an injection current density just below threshold were about 10 and 26 nm, respectively. These results confirm that the blueshift in quantum-wells fabricated on m-plane oriented substrates is smaller than on c-plane oriented substrates due to the absence of polarization-induced electric fields.
TL;DR: In this article, Simulated emission in the blue-green (480 nm) and green (514 nm) regime has been observed, at room temperature (RT) under optical pumping, from nonpolar m-plane (1010) and semipolar (1122) InGaN multi-quantum well (MQW) laser diode (LD) structures, respectively, grown on bulk GaN substrates.
Abstract: Stimulated emission (SE) in the blue-green (480 nm) and green (514 nm) regime has been observed, at room temperature (RT) under optical pumping, from nonpolar m-plane (1010) and semipolar (1122) InGaN multi-quantum well (MQW) laser diode (LD) structures, respectively, grown on bulk GaN substrates. The emission intensity exhibited a clear threshold behavior with respect to the pump power. Optical anisotropy was also observed between the two perpendicular in-plane directions [1123] and [1010] for semipolar LD structures, with significantly lower pump thresholds for emission along [1123]. The SE wavelength, measured just above threshold, was blue-shifted with respect to the spontaneous emission wavelength measured just below threshold. These initial results indicate that semipolar (1122) GaN is a promising orientation for the realization of blue-green and green LDs.
TL;DR: A lowering of the threshold pump power is demonstrated from a off-resonance value of 37 microW to 18 microW when an individual quantum dot exciton is on-Resonance with the cavity mode.
Abstract: Lasing effects based on individual quantum dots have been investigated in optically pumped high-Q micropillar cavities. We demonstrate a lowering of the threshold pump power from a off-resonance value of 37 microW to 18 microW when an individual quantum dot exciton is on-resonance with the cavity mode. Photon correlation studies below and above the laser threshold confirm the single dot influence. At resonance we observe antibunching with g((2))(0) = 0.36 at low excitation, which increases to 1 at about 1.5 times the threshold. In the off-resonant case, g((2))(0) is about 1 below and above threshold.
TL;DR: In this paper, the spectral properties of Sm3+ (1 mol%) ions in 49 PbO-30 GeO2-20 TeO2 glass have been characterized through optical absorption and temperature dependent fluorescence.
Abstract: Spectroscopic properties of Sm3+ (1 mol%) ions in 49 PbO–30 GeO2–20 TeO2 glass have been characterized through optical absorption and temperature dependent fluorescence. The spectroscopic parameters such as oscillator strengths (f), Judd–Ofelt (J–O) intensity parameters (Ωλ), spontaneous emission probability (AR), branching ratios (βR) and radiative lifetimes (τR) of various excited levels have been determined from the absorption spectrum by using J–O analysis. From the fluorescence spectra, four emission transitions have been observed from the 4 G5/2 state to the lower lying states 6H5/2, 6H7/2, 6H9/2 and 6H11/2 upon exciting the sample with a 488 nm line of an argon ion laser. The stimulated emission cross-sections (σe) and branching ratios (βmeas) were estimated from the emission spectra for all emission transitions and decay curve analysis for the 4G5/2 level has also been carried out for different concentrations. Based on these results, the utility of Sm3+ doped lead–germanate–tellurite glasses as laser active materials in the visible region is discussed.
TL;DR: In this paper, the authors presented a high performance continuous-wave quantum-cascade laser with spontaneous emission full-width at half-maximum as large as 295 cm-1.
Abstract: Based on the bound-to-continuum active region design, we shall present a high performance continuous-wave (CW) quantum-cascade laser. In contrast to high performance lasers based on a two-phonon resonance transition and a narrow linewidth (< 165 cm-1), the device presented here exhibits a spontaneous emission full-width at half-maximum as large as 295 cm-1. Thus, such devices are very suitable for broadband tuning. At 30degC, it shows a maximum output power and slope efficiency of 188 mW and 500 mW/A, as well as a threshold current density of only 1.79 kA/cm2. Furthermore, at this temperature, the device demonstrates an internal differential quantum efficiency of 71% and a wall plug efficiency of 2.0%. The maximum CW operation temperature reached is 110degC. A thermal resistance of 4.3 K/W was attained by epi-down mounting on diamond submounts. The waveguide losses of 14 cm-1 are explained by intersubband absorption in addition to free-carrier absorption.