This paper reports the effect of homogeneous broadening optical gain on lasing spectra in self-assembled ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ quantum dot lasers. We measured current-output power characteristics and light-emission for columnar-shaped ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ quantum-dot lasers that show from ground state. While occurred with a narrow line including few...

We grew 1.3-µm emitting self-formed In 0.5 Ga As quantum dots on GaAs substrates by supplying InAs and monolayers alternately during atomic layer epitaxy. The were 20 nm in diameter 10 height, surrounded 0.1 0.9 the lateral direction perpendicular to dots. Diamagnetic energy shifts of excitons clearly demonstrated three-dimensional confinement.

We demonstrate the first 1.3-μm continuous-wave (CW) lasing at room temperature of self-assembled InGaAs-GaAs quantum dots. High-density emission dots were successfully formed by combination low-rate growth and InGaAs-layer overgrowth methods molecular beam epitaxy. The ground-level CW occurred up to 40/spl deg/C, threshold current 8 mA 25/spl deg/C is less than one thirtieth values ever reported for dot pulse lasers. achievement represents a milestone creating quantum-dot lasers applicable...

The effect of phonon bottleneck on quantum-dot laser performance is examined by solving the carrier-photon rate equations including carrier relaxation process into ground state. We show that retarded due to degrades threshold current and external quantum efficiency. also lasers are quite sensitive crystal quality outside as well inside dots. Our results clarified lifetime should be less than about 10 ps fully utilize potential originating from discrete energy states.

We studied the excitation-power dependence of photoluminescence (PL) spectra and current electroluminescence (EL) self-formed InGaAs/GaAs quantum dots. observed five peaks in PL EL spectra. From size peak interval carrier-density energy intensity, we assigned to discrete levels simulated with rate equations, taking into account carrier relaxation between levels, found that lifetime was about 10–100 ps.

A laser oscillation from self-organized In/sub 0.5/Ga/sub 0.5/As quantum dots is achieved at 80 K by current injection. Lasing a three-dimensionally confined sublevel of the clearly demonstrated for first time electroluminescence and diamagnetic energy shift measurement. The results predict possibility ultra-low threshold operation dot lasers.

Ultrafast gain dynamics in quantum-dot (QD) optical amplifiers has been studied. It was found that there are at least three nonlinear processes, which attributed to carrier relaxation the ground states, phonon scattering, and capture from wetting layers into QDs. The relevant time constants were evaluated be /spl sim/90 fs, sim/260 sim/3 ps, respectively, under a 50-mA bias condition. dephasing sim/85 fs. third-order susceptibility (/spl chi//sup (3)/) by means of both transmission four-wave...

This paper presents the lasing properties and their temperature dependence for 1.3-/spl mu/m semiconductor lasers involving self-assembled InGaAs-GaAs quantum dots as active region. High-density emission were successfully grown by combination of low-rate growth InGaAs-layer overgrowth using molecular beam epitaxy. ground-level CW occurring at a low threshold current 5.4 mA 25/spl deg/C with realistic cavity length 300 /spl high-reflectivity coatings on both facets. The internal loss was...

We demonstrate experimentally that a photon bottleneck for carrier relaxation does exist in self-formed ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}/\mathrm{GaAs}$ quantum dots. With time-resolved photoluminescence, we measured the lifetime and radiative recombination five discrete levels as function of temperature. found higher temperature level were, shorter was (1 ns-10 ps). The about 1 ns to be independent also simulated electroluminescence spectra at 77 300 K with...

We examined the current–output power characteristics and light emission spectra for columnar-shaped self-assembled InGaAs quantum-dot lasers with a room temperature lasing threshold of 6 mA. Lasing currents became obscure as decreased below 180 K. While occurred one line including series longitudinal modes at temperature, 80 K showed broad over range 50–60 meV. conclude that dots different energies start independently low temperatures due to their spatial localization, while contribute...

Room temperature CW operation at the ground state has been achieved in self-formed quantum dot lasers with a multi-stacked layer. By systematic investigation, discontinuous shifts of lasing wavelength from high-order sub-bands to are clearly demonstrated by varying number layers and cavity loss.

Temperature dependence of self-formed quantum dot lasers with a multi-stacked layer has been investigated in detail. Lasers oscillating at different subbands exhibit behaviors against temperature change both the spectral characteristics and threshold current. A discontinuous shift lasing wavelength from second subband to ground state is observed lowering temperature, which strongly related emission efficiency dots thermal excitation carriers higher-order subbands. High characteristic over...

We propose a simple and innovative configuration consisting of quantum dot micro-optical resonator that emits single photons with good directionality in plane parallel to the substrate. In this device, is placed as light source between slits triangular split-ring (SRR) supported an optical polymer film air-bridge structure. Although most previous photon emitters solid-state devices emitted upward from substrate, operation simulations confirmed realizes lateral emission narrow regions above,...

Wavelength conversion using nondegenerate four-wave mixing in quantum-dot optical amplifiers is investigated. From the detuning frequency dependence of χ(3), derived from efficiency, we consider that, within range experiment, spectral-hole burning and carrier heating are responsible, that their time constants, i.e., relaxation to ground state phonon scattering time, 60–140 200–400 fs, respectively. This indicates supply level via higher levels very fast a broad bandwidth comparable...

We investigated the photoluminescence (PL) intensity of InGaAs/GaAs quantum dots self-formed by atomic layer epitaxy (ALE) technique as a function temperature. report that reduction PL following temperature increase was two-orders smaller in ALE-grown than grown molecular beam via Stranski–Krastanov mode. Measuring radiative lifetimes and evaluating dependence intensity, we conclude nonradiative channel outside caused reduction.

Lasers with a new type of quantum dot achieve low threshold current and high output power. By supplying small amount InAs GaAs alternately on substrates, dots uniformity emission efficiency were self-assembled. The lasers exhibited 5.4 mA, density 160 A/cm2, an power 110 mW at room temperature.

This letter reports on the high characteristic temperature of InGaAs/GaAs quantum-dot lasers at room temperature. Self-assembled quantum dots were grown using low-growth-rate molecularbeam epitaxy, and continuous-wave lasing occurred dot ground level 1.26 μm 25 °C. The threshold currents was 120 K, ground-level observed up to 100 Comparing performances spontaneous emission spectra with those 1.3 dots, we found that large volume density, deep potential, efficiency key points for improving...

A nonlinear device capable of handling multiple wavelength channels simultaneously by using spectral-hole burning in the inhomogeneous broadening gain self-assembled quantum dots is proposed. The multichannel property this stems from localized absorption or change at pump within inhomogeneously broadened spectrum. spectral width modulation and its time evolution was also evaluated. result indicates applicability to operation.

We found that the temperature sensitivity of interband emission energy was suppressed significantly in 1.3-μm-emitting self-assembled InGaAs/GaAs quantum dots by an InGaAs overgrowth on dots. Transmission electron microscopy measurements indicated lattice distortion enhanced a 10-nm-thick InxGa1−xAs layer. Photoluminescence spectra showed shift with increasing nearly negligible above 150 K when x⩾0.25. The between 4.2 and 200 less than half bulk GaAs x=0.3. results reveal potential...

Abstract We report the method to fabricate SnSe nanosheet (NSs) coated solar cells with very high performance compared similar previously reported using chemically synthesized nanocrystals. NSs do not contain toxic metals and are promising materials for top layer of tandem cells. hot injection were suitable coating as a light absorption because their nonuniform size tendency aggregate. The one-pot synthesis produced uniform size, making them fabricating flat homogeneous films when mixed...

Room-temperature continuous-wave (CW) operation at the ground state has been achieved in self-formed quantum-dot lasers with multistacked dot layer. By systematic investigation, discontinuous shifts of lasing wavelength from high-order subbands to are clearly demonstrated for first time by varying number layers and cavity loss. Lasers oscillating different exhibit behaviors against temperature both spectral characteristics threshold currents, which strongly related emission efficiency...

This paper reports recent developments of our self-assembled InGaAs quantum-dot (QD) lasers and their unique physical properties. We achieved a low-threshold current 5.4 mA at room temperature with originally designed columnar-shaped QD's, also, room-temperature 1.3-/spl mu/m continuous-wave (CW) lasing dots grown decreased growth rate covered by strained layer. discuss influence homogeneous broadening single-dot optical gain on spectra, nonradiative carrier recombination characteristics...